action: /say ##c is for discussion involving the C programming language itself. We do not deal with the whole range of the spectrum. libgtk may be written in C, but this is hardly the proper channel for GTK-related questions. Try #gtk. Likewise, makefiles and autotools: #devtools, assembly: #asm, Xlib: #xlib, C++: #c++, and so on.
action: a *printf format specifier which converts its signed int argument to decimal representation; a *scanf format specifier which parses a decimal representation to its int* argument
action: the bitwise inclusive-AND assignment operator. The expression (x &= y) is equivalent to (x = x & y) except that the expression x is evaluated only once.
action: the multiplication binary operator. It is also the unary pointer dereference operator. It is also used in declarations to declare a variable which is a pointer to a type: <type> *p;
action: a unary operator that increments basic types by 1; if it is placed before a variable the value of the expression is: <var> + 1; if it is placed after a variable the value of the expression is: <var>
action: the sequence operator. It is also used to separate syntactic elements of: function arguments in a function call, declarators (in declarations of the same type), formal parameters in function declarations, enumeration elements, and initializers.
action: a unary operator that decrements basic types by 1; if it is placed before a variable the value of the expression is: <var> - 1; if it is placed after a variable the value of the expression is: <var>
action: a GCC flag that issues all warnings demanded by strict ISO C; rejects most programs that use forbidden extensions; should not be used to check for strict ISO conformance as it only warns for coding practices that _require_ a diagnostic, not everything; loosely supported
action: a GCC flag that is used to specify which C standard to follow when compiling; some valid standards are: c89 (-ansi), c99, gnu89 (default), gnu99
action: a question mark. Stop staring stupidly off into space with a question mark above your head, wipe that drool off your chin and make an intelligent query.
action: a misnomer. These two languages are completely different languages with each having its own standard. C++ is not a "superset" of C. For C++ questions, please join #C++
action: the informal name given to a technique where a function takes in, as arguments, other functions by way of pointers allowing access to multiple functions of the same prototype (per argument). In essence it provides, for each passed argument, algorithm-agnostic function switching/access
action: an integer constant expression, with type int and a negative value, that is returned by several functions to indicate end-of-file (ISO/IEC 9899:1999 7.19.1p3). It is NOT a char. It is NOT a byte that is stored at the end of every file.
action: "C - A Reference Manual" by Harbison & Steele; a reference for C on par with K&R - http://www.amazon.com/Reference-Manual-Samuel-P-Harbison/dp/013089592X
action: The C Programming Language, 2nd edition, by Kernighan and Ritchie -- http://wayback.archive-it.org/5263/20150203070038/http://cm.bell-labs.com/cm/cs/cbook/ -- errata: http://www.iso-9899.info/2ediffs.html
action: #include <limits.h> - maximum number of bytes in a mult-byte character for an extended character in the current locale, which is never greater than MB_LEN_MAX.
action: an (implementation-defined) macro expanding to a null pointer constant, which is any zero-value integer constant expression, possibly cast to void *. Such an expression has a special meaning in the context of pointer expressions to, for example, produce null pointers or test if other pointers are null pointers.
action: /say Undefined behavior is behavior for which the C standard does not impose any requirements. This is to allow C the freedom to be implemented on systems with different architectures. Programs invoking undefined behavior may appear to compile and even run without errors at first, only to fail on another system, or even at a later time. If you want to write reliable code, don't use such behaviors.
action: /say Unspecified behavior is behavior for which the C standard provides two or more possibilities, and imposes no further requirements on which behavior is chosen in any instance. Not to be confused with undefined behavior or implementation dependent behavior.
action: the line continuation character; used in strings to specify special characters; used in character constants to specify special characters; when followed by u or U in C99, is used to specify a universal character name for use in string constants, character constants, or identifiers.
action: /say All identifiers that begin with an underscore and either an uppercase letter or another underscore are always reserved for any use. All identifiers that begin with an underscore are always reserved for use as identifiers with file scope in both the ordinary and tag name spaces. (ISO 9899:1999, 7.1.3) Don't use such identifiers.
action: /say C has pointer types and addresses (or pointer values). foo x; &x results in an address that points to an object. foo *y; y is an instance of a pointer type. Instances of pointer types do not magically point to objects. They must be assigned to before being used, for example: y = &x;
action: the traditional name of the first parameter to main(); argc is non-negative and gives the number of command line arugments (including the program name).
action: the traditional name of the second parameter to main(); argv[argc] == NULL; if argc>0 argv[0] is the program name. if argc>1, argv[1] through argv[argc-1] are the command line arguments.
action: evil. It does no overflow checking, handles unsigned numbers poorly, and handles strings containing trailing characters (like ``123abc'') poorly. Use strtol() instead.
action: /say The `auto` keyword specifies that the object has automatic storage duration (which is the default storage duration of objects, hence its use is redundant and rare)
action: /say A bit is a unit of data storage large enough to hold an object that may have one of two values. It need not be possible to express the address of each individual bit of an object.
action_with_args: /me points accusingly at $args, "Where is your book?!" See http://www.iso-9899.info/wiki/Books for some useful book recommendations, including free online resources.
action: defined by the C standard as an addressable unit of storage large enough to hold a character value. The char type is byte-sized and is at least 8 bits wide. CHAR_BIT in <limits.h> defines the byte size for any given implementation. The term "byte" is most often used to mean 8 bits; however, the term "octet" is preferred.
action: /say If you are using a C++ compiler then your code is not C -- even if you're only using the "C subset". As soon as you invoke a C++ compiler instead of a C compiler, all the rules and idiosyncrasies of the C++ specification come into play, which have subtle differences in certain semantics. Please ask ##c++ or switch to a C compiler.
action: /say C Aphorism 13: The newbie will fail to recognize undefined behavior, and will wrongly think that their program is correct because it appears to work.
action: /say C Aphorism 15: When multiple people respond to the questioner's problem, the questioner will focus on the person giving incorrect advice and ignore everybody else.
action: /say C Aphorism 2: All examples given by the questioner will be incomplete, misleading, broken, wrong, and/or not representative of the actual question.
action: /say C Aphorism 7: The questioner will paste code and say "I have a problem" or "It doesn't work" without any further information or description of the problem.
action: /say C89/C90 draft: http://port70.net/~nsz/c/c89/c89-draft.html or http://flash-gordon.me.uk/ansi.c.txt or http://web.archive.org/web/20050207005628/http://dev.unicals.com/papers/c89-draft.html - C Overview: http://en.wikipedia.org/wiki/C_programming
action: /say A Standard C vim syntax file: http://www.vim.org/scripts/script.php?script_id=234 -- adds numerous improvements to vim C syntax highlighting, including C99 features and more!
action: /say "In C, all function arguments are passed ‘‘by value.’’ This means that the called function is given the values of its arguments in temporary variables rather than the originals." (K&R)
action: /say A callback function abstracts some aspect of work which is independent of a particular algorithm. An implementation of that algorithm is passed a pointer to that function, and "calls back" for the abstracted work to be done. For code samples, see: http://www.iso-9899.info/wiki/Callback
action: /say "In C, all function arguments are passed ‘‘by value.’’ This means that the called function is given the values of its arguments in temporary variables rather than the originals." (K&R)
action: a function that allocates a block of memory for an array of "num" elements, each of them "size" bytes long, AND initializes all its bits to zero. The effective result is the allocation of a zero-initialized memory block of (num*size) bytes. see http://claudihome.com/html/LR/function_reference/Content/c_language/lrFuncRef_CLang_calloc.htm
action: The C Abstract Machine - An abstract machine used for reasoning about the semantics described in the C-std, in which issues of optimization are irrelevant.
action: /say ##c is not the place to have others do your homework. If you don't understand parts of your assignment, feel free to ask but don't expect others to do your homework.
action: http://code.google.com/p/pbot2-pl/source/browse/trunk/modules/compiler_vm/ <-- download: cc, compiler_vm_server.pl, compiler_vm_client.pl, compiler_watchdog.pl and debugcommands -- Now you too can use cc in on your shell command-line! See the README, as well.
action: /say char is required to be able to represent (at least) the values inclusively between -127 and 127 (signed char), or 0 and 255 (unsigned char). The representation chosen is implementation-defined, meaning some compilers will treat a char as signed, others unsigned. sizeof (char) is always 1. See also: CHAR_BIT, CHAR_MIN, CHAR_MAX and byte
action: /say OK, it's getting a little hairy, and really we're all here because we love C. So relax, take a walk, have a cuppa, whatever. Er.. please? ;)
action: /say Proposal to add methods() to C structures: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1816.pdf (Briefly discussed in section 6.3 (page 8) of http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1820.pdf) and also http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1875.htm
action: /say If you have multiple structs that share a common initial sequence, you can generalize the access to this sequence by either containing the sequence within a sub-struct, or by using a union to contain the structs. See: http://www.iso-9899.info/wiki/Common_Initial_Sequence
action: /say Order Matters: CC <overall options> [-std=whatever] <debugging> <optimizing> <warnings> [-pedantic] <Other Include Paths> <Other Lib Paths> <Magic Defines> <Magic Undefines> [-f<language/platform options] [-m<machine options>] [-o outfile] files..... (this is all documented, and files can be .c or .o, .a or .so, or -l<to be linked> commands.) <paraphrased from man gcc>
action: /say The const qualifier is not the same as a constant. The following code sample is not required to compile: const int i = 123; int y = i; int main(void) {}
action: /say Computer programming is a process that leads from an original formulation of a problem to executable programs. It involves activities such as analysis, understanding, and generically solving such problems resulting in an algorithm, verification of requirements (including correctness, resource consumption, etc) and maintaining the source code.
action: /say cplusplus-dot-com is a C++-related website that happens to reference C89 functions. Many of the examples given are actually C++ because they use 'headers' such as <cstdio> instead of <stdio.h>. A better reference would be the C99/C11 standard.
action: /say cprogramming.com is not a site to be recommended to C learners because it "provide you with C and C++ programming language resources". Find a resource that distinctly teaches C to avoid confusion. See !books.
action: /say Paste sites to be avoided include: codepaste.net, paste.awesom.eu, paste.jhvisser.com, paste.ofcode.org, paste.ubuntu.com, paste2.org, pastebin.fr, pastebin.ubuntu.com, pastee.org, vpaste.net, www.pasteall.org. These sites make it unnecessarily difficult to access the raw paste data, making it less likely for you to get help with. See the channel topic for recommended sites.
action: /say Decaying implies permanence. Arrays do not "decay"; it is the expression that is converted, not the array. In most cases, an expression that has type "array of T" is converted to an expression with type "pointer to T" that points at the first element. See C11 6.3.2.1p3 for the exceptions.
action: A declaration specifies the interpretation and attributes of a set of identifiers. A definition of an identifier is a declaration for that identifier that: for an object, causes storage to be reserved for that object; for a function, includes the function body; for an enumeration constant or typedef name, is the (only) declaration of the identifier.
action: /say In C, declaration follows use. That means you do not write `char* p` but instead `char *p` because it doesn't mean `p is a pointer to char` but rather `*p is a char`. https://www.quora.com/Why-doesnt-C-use-better-notation-for-pointers
action: Expert C Programming: Deep C Secrets by Peter van der Linden. It assumes some foundation in the C programming language and covers its dustier corners as well as common misconceptions, such as array-pointer equivalence. See: http://www.amazon.com/Expert-Programming-Peter-van-Linden/dp/0131774298
action: /say C99 added designators for initializers. Designator for an element of an array: int arr[3] = { [2] = 123 }; Designator for a member of a struct (or union): struct { int x; int y; } s = { .y = 123 };
action: /say Diagnostics can help you find issues with your code. For decent diagnostics you should compile your code using gcc or clang with the flags: -std=c99 -Wall -Wextra -Wpedantic. See also: clang-analyze, cppcheck, and valgrind
action: a two character alternative punctuator, intended to make using c possible on systems where the primary punctuator is missing, typically from keyboards. they are normal tokens, so are processed in the same way as other source characters (apart from trigraphs).
action: /say Standard C neither knows nor cares about colors, mice, windows, keyboards, networks or any other system-specific things. If you wanted help with something like that, you would want to tell us what OS, compiler, tools or libraries you intend to use/abuse, or find the appropriate channel.
action: /say There is no need to cast the result of library functions that return void *; it makes your code hard to read, adds no value, and can hide a bug if you don't have a valid prototype in scope. See http://c-faq.com/malloc/mallocnocast.html
action: /say When taking input for type double you need to use lf format specifier in the scanf statement. But when you are outputting a double you use f format specifier in the printf statements.
action: /say When reading The C Programming Language, 2nd edition, by Kernighan and Ritchie, make sure you check the errata as well: http://www.iso-9899.info/2ediffs.html
action: library error macro, #include <errno.h> The macro designates a modifiable int object that is asigned a value greater than zero on certain library errors. see http://www.iso-9899.info/man?strerror
action: /say The last element of a structure with more than one named member may have an incomplete array type; this is called a flexible array member (C99 6.7.2.1p16). struct s { int n; double d[]; } *p = malloc(sizeof *p + 17 * sizeof *p->d);
action: /say There's little need to make generalizations about people who program with C. Some have interesting prejudices, others don't. In any case it will depend on the individual, and not the fact that they have a preference for a particular language.
action: /say You can convert a function pointer of one type to a function pointer of a different type for passing it as an argument to a function, but upon calling the function the pointed-to type should be compatible*. See http://www.iso-9899.info/wiki/Generic_Function_Pointer
action: declared in stdio.h in POSIX 2008, but is not a standard C function. To compile your own code that defines a "getline" function, you may need to use -ansi or make sure you are not using POSIX (or GNU) feature test macros. On Mac OS X, use -D_ANSI_SOURCE.
action: very bad. It cannot be told the size of the buffer to read in, therefore it has no way of preventing buffer overflows. Use fgets() with 'stdin' as the FILE* instead. http://www.eskimo.com/~scs/C-faq/q12.23.html
action: /say Don't use github for pasting. The line numbers are in a different font size to the code, and as a result they don't line up with lines of code correctly.
action: /say There is no "global" scope in C. There are four kinds of scopes: function, file, block, and function prototype. A variable that appears outside of any block or list of parameters has file scope, which terminates at the end of the translation unit.
action: /say Goto statements can be useful for cleaning up or breaking out of nested loops/switches. See cleanup and http://www.iso-9899.info/wiki/Goto
action: Hacker's Delight by Henry S. Warren Jr. It discusses the use of boolean algebra and bitwise operations to reduce the computational complexity of algorithms. See http://www.hackersdelight.org and http://www.amazon.com/Hackers-Delight-Edition-Henry-Warren/dp/0321842685
action: /say C does not require implementations to use stacks or heaps. Please refer to the actually defined storage durations, which are four: allocated, automatic, thread and static.
action: /say An identifier can denote an object; a function; a tag or a member of a structure, union, or enumeration; a typedef name; a label name; a macro name; or a macro parameter. The same identifier can denote different entities at different points in the program.
action: the keyword that tests a bracketed expression and if true, executes the following statement; if the expression evaluates to false an optional ''else'' clause is executed
action: a particular set of software, running in a particular translation environment under particular control options, that performs translation of programs for, and supports execution of functions in, a particular execution environment (ISO/IEC 9899:1999 3.12)
action: /say If you are not experienced enough to adhere to coding style allowing production of readable C code, brush your source automatically: using GNU indent http://gnu.org/s/indent/, using clang-format http://clang.llvm.org/docs/ClangFormat.html, or using astyle http://astyle.sourceforge.net/
action: /say A common idiom for zero initializing elements of arrays or members of structs (automatic storage duration) is: char arr[10] = { 0 }; struct { int x; int y;} s = { 0 };
action: /say A function declared with an inline function specifier is an inline function. Making a function an inline function suggests that calls to the function be as fast as possible. If you use `inline', always use `static', too. See https://kellett.im/a/inline
action: a signed integer data type, at least 16 bits wide, which must be able to represent (at least) all the numbers in the range -32767 to +32767. Its lowest value, INT_MIN, and highest value, INT_MAX, are defined in <limits.h>
action: /say Some of us no longer primarily recommend K&R because it's somewhat outdated and unmaintained. It's tiresome reminding would-be readers of implicit int's removal in modern C, among many other issues. The errata that addresses only some of these issues no longer exists on the official site. If a 3rd edition of K&R emerges that rectifies these issues, we'll happily recommend it again!
action: /say 'The C Programming Language' (2nd Ed, 1988) aka K&R2, is a book that teaches C89, it has a lengthy errata and it contains 'old style' things. The book is short (272 pages) and as such less informative. 'C Programming: A Modern Approach' by K. N. King (2nd Ed, 2008) covers both C89 and C99, it's very much informative and therefore lengthy (832 pages).
action: /say 'C Programming: A Modern Approach' by K. N. King (2nd Ed, 2008) is a recommended C book that teaches both C89 and C99. http://knking.com/books/c2/index.html
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-1. Run the ‘‘hello, world’’ program on your system. Experiment with leaving out parts of the program, to see what error messages you get.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-10. Write a program to copy its input to its output, replacing each tab by \t, each backspace by \b, and each backslash by \\. This makes tabs and backspaces visible in an unambiguous way.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-11. How would you test the word count program? What kinds of input are most likely to uncover bugs if there are any?
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-13. Write a program to print a histogram of the lengths of words in its input. It is easy to draw the histogram with the bars horizontal; a vertical orientation is more challenging.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-14. Write a program to print a histogram of the frequencies of different characters in its input.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-15. Rewrite the temperature conversion program of Section 1.2 to use a function for conversion.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-16. Revise the main routine of the longest-line program so it will correctly print the length of arbitrary long input lines, and as much as possible of the text.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-18. Write a program to remove trailing blanks and tabs from each line of input, and to delete entirely blank lines.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-19. Write a function reverse(s) that reverses the character string s. Use it to write a program that reverses its input a line at a time.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-2. Experiment to find out what happens when prints’s argument string contains \c, where c is some character not listed above.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-20. Write a program detab that replaces tabs in the input with the proper number of blanks to space to the next tab stop. Assume a fixed set of tab stops, say every n columns. Should n be a variable or a symbolic parameter?
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-21. Write a program entab that replaces strings of blanks by the minimum number of tabs and blanks to achieve the same spacing. Use the same tab stops as for detab. When either a tab or a single blank would suffice to reach a tab stop, which should be given preference?
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-22. Write a program to ‘‘fold’’ long input lines into two or more shorter lines after the last non-blank character that occurs before the n-th column of input. Make sure your program does something intelligent with very long lines, and if there are no blanks or tabs before the specified column.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-23. Write a program to remove all comments from a C program. Don’t forget to handle quoted strings and character constants properly. C comments don’t nest.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-24. Write a program to check a C program for rudimentary syntax errors like unmatched parentheses, brackets and braces. Don’t forget about quotes, both single and double, escape sequences, and comments. (This program is hard if you do it in full generality.)
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-5. Modify the temperature conversion program to print the table in reverse order, that is, from 300 degrees to 0.
action: /say Chapter 1: A Tutorial Introduction; Exercise 1-9. Write a program to copy its input to its output, replacing each string of one or more blanks by a single blank.
action: /say Chapter 2: Types, Operators and Expressions; Exercise 2-1. Write a program to determine the ranges of char, short, int, and long variables, both signed and unsigned, by printing appropriate values from standard headers and by direct computation. Harder if you compute them: determine the ranges of the various floating-point types.
action: /say Chapter 2: Types, Operators and Expressions; Exercise 2-10. Rewrite the function lower, which converts upper case letters to lower case, with a conditional expression instead of if-else.
action: /say Chapter 2: Types, Operators and Expressions; Exercise 2-2. Write a loop equivalent to the for loop above without using && or ||. [The for loop is: for (i=0; i < lim-1 && (c=getchar()) != ’\n’ && c != EOF; ++i) s[i] = c;]
action: /say Chapter 2: Types, Operators and Expressions; Exercise 2-3. Write a function htoi(s), which converts a string of hexadecimal digits (including an optional 0x or 0X) into its equivalent integer value. The allowable digits are 0 through 9, a through f, and A through F.
action: /say Chapter 2: Types, Operators and Expressions; Exercise 2-4. Write an alternative version of squeeze(s1,s2) that deletes each character in s1 that matches any character in the string s2.
action: /say Chapter 2: Types, Operators and Expressions; Exercise 2-5. Write the function any(s1,s2), which returns the first location in a string s1 where any character from the string s2 occurs, or -1 if s1 contains no characters from s2. (The standard library function strpbrk does the same job but returns a pointer to the location.)
action: /say Chapter 2: Types, Operators and Expressions; Exercise 2-6. Write a function setbits(x,p,n,y) that returns x with the n bits that begin at position p set to the rightmost n bits of y, leaving the other bits unchanged.
action: /say Chapter 2: Types, Operators and Expressions; Exercise 2-7. Write a function invert(x,p,n) that returns x with the n bits that begin at position p inverted (i.e., 1 changed into 0 and vice versa), leaving the others unchanged.
action: /say Chapter 2: Types, Operators and Expressions; Exercise 2-8. Write a function rightrot(x,n) that returns the value of the integer x rotated to the right by n positions.
action: /say Chapter 2: Types, Operators and Expressions; Exercise 2-9. In a two’s complement number system, x &= (x-1) deletes the rightmost 1-bit x. Explain why. Use this observation to write a faster version of bitcount.
action: /say Chapter 3: Control Flow; Exercise 3-1. Our binary search makes two tests inside the loop, when one would suffice (at the price of more tests outside.) Write a version with only one test inside the loop and measure the difference in run-time.
action: /say Chapter 3: Control Flow; Exercise 3-2. Write a function escape(s,t) that converts characters like newline and tab into visible escape sequences like \n and \t as it copies the string t to s. Use a switch. Write a function for the other direction as well, converting escape sequences into the real characters.
action: /say Chapter 3: Control Flow; Exercise 3-3. Write a function expand(s1,s2) that expands shorthand notations like a-z in the string s1 into the equivalent complete list abc...xyz in s2. Allow for letters of either case and digits, and be prepared to handle cases like a-b-c and a-z0-9 and -a-z. Arrange that a leading or trailing - is taken literally.
action: /say Chapter 3: Control Flow; Exercise 3-4. In a two’s complement number representation, our version of itoa does not handle the largest negative number, that is, the value of n equal to -(2^(wordsize-1)). Explain why not. Modify it to print that value correctly, regardless of the machine on which it runs.
action: /say Chapter 3: Control Flow; Exercise 3-5. Write the function itob(n,s,b) that converts the integer n into a base b character representation in the string s. In particular, itob(n,s,16) formats n as a hexadecimal integer in s.
action: /say Chapter 3: Control Flow; Exercise 3-6. Write a version of itoa that accepts three arguments instead of two. The third argument is a minimum field width; the converted number must be padded with blanks on the left if necessary to make it wide enough.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-1. Write the function strindex(s,t) which returns the position of the rightmost occurrence of t in s, or -1 if there is none.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-10. An alternate organization uses getline to read an entire input line; this makes getch and ungetch unnecessary. Revise the calculator to use this approach.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-11. Modify getop so that it doesn’t need to use ungetch. Hint: use an internal static variable.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-12. Adapt the ideas of printd to write a recursive version of itoa; that is, convert an integer into a string by calling a recursive routine.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-13. Write a recursive version of the function reverse(s), which reverses the string s in place.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-14. Define a macro swap(t,x,y) that interchanges two arguments of type t. (Block structure will help.)
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<kr4-2>
action: /say Chapter 4: Functions and Program Structure; Exercise 4-2. Extend atof to handle scientific notation of the form 123.45e-6 where a floating-point number may be followed by e or E and an optionally signed exponent.
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<kr4-3>
action: /say Chapter 4: Functions and Program Structure; Exercise 4-3. Given the basic framework, it’s straightforward to extend the calculator. Add the modulus (%) operator and provisions for negative numbers.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-4. Add the commands to print the top elements of the stack without popping, to duplicate it, and to swap the top two elements. Add a command to clear the stack.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-5. Add access to library functions like sin, exp, and pow. See <math.h> in Appendix B, Section 4.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-6. Add commands for handling variables. (It’s easy to provide twenty-six variables with single-letter names.) Add a variable for the most recently printed value.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-7. Write a routine ungets(s) that will push back an entire string onto the input. Should ungets know about buf and bufp, or should it just use ungetch?
action: /say Chapter 4: Functions and Program Structure; Exercise 4-8. Suppose that there will never be more than one character of pushback. Modify getch and ungetch accordingly.
action: /say Chapter 4: Functions and Program Structure; Exercise 4-9. Our getch and ungetch do not handle a pushed-back EOF correctly. Decide what their properties ought to be if an EOF is pushed back, then implement your design.
action: /say Chapter 5: Pointers and Arrays; Exercise 5-1. As written, getint treats a + or - not followed by a digit as a valid representation of zero. Fix it to push such a character back on the input.
action: /say Chapter 5: Pointers and Arrays; Exercise 5-10. Write the program expr, which evaluates a reverse Polish expression from the command line, where each operator or operand is a separate argument. For example, expr 2 3 4 + * evaluates 2 * (3 + 4).
action: /say Chapter 5: Pointers and Arrays; Exercise 5-11. Modify the program entab and detab (written as exercises in Chapter 1) to accept a list of tab stops as arguments. Use the default tab settings if there are no arguments.
action: /say Chapter 5: Pointers and Arrays; Exercise 5-12. Extend entab and detab to accept the shorthand `entab -m +n` to mean tab stops every n columns, starting at column m. Choose convenient (for the user) default behavior.
action: /say Chapter 5: Pointers and Arrays; Exercise 5-13. Write the program tail, which prints the last n lines of its input. By default, n is set to 10, let us say, but it can be changed by an optional argument so that `tail -n` prints the last n lines. The program should behave rationally no matter how unreasonable the input or the value of n. Write the program so that it makes the best use of available storage; lines should be stored as in the sorting program of Section 5.6, not in a two-dimensional array of fixed size.
action: /say Chapter 5: Pointers and Arrays; Exercise 5-14. Modify the sort program to handle a -r flag, which indicates sorting in reverse (decreasing) order. Be sure that -r works with -n.
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<kr5-15>
action: /say Chapter 5: Pointers and Arrays; Exercise 5-15. Add the option -f to fold upper and lower case together, so that case distinctions are not made during sorting; for example, a and A compare equal.
action: /say Chapter 5: Pointers and Arrays; Exercise 5-16. Add the -d (‘‘directory order’’) option, which makes comparisons only on letters, numbers and blanks. Make sure it works in conjunction with -f.
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<kr5-17>
action: /say Chapter 5: Pointers and Arrays; Exercise 5-17. Add a field-searching capability, so sorting may bee done on fields within lines, each field sorted according to an independent set of options. (The index for this book was sorted with -df for the index category and -n for the page numbers.)
action: /say Chapter 5: Pointers and Arrays; Exercise 5-2. Write getfloat, the floating-point analog of getint. What type does getfloat return as its function value?
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<kr5-20>
action: /say Chapter 5: Pointers and Arrays; Exercise 5-20. Expand dcl to handle declarations with function argument types, qualifiers like const, and so on.
action: /say Chapter 5: Pointers and Arrays; Exercise 5-3. Write a pointer version of the function strcat that we showed in Chapter 2: strcat(s,t) copies the string t to the end of s.
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<kr5-4>
action: /say Chapter 5: Pointers and Arrays; Exercise 5-4. Write the function strend(s,t), which returns 1 if the string t occurs at the end of the string s, and zero otherwise.
action: /say Chapter 5: Pointers and Arrays; Exercise 5-5. Write versions of the library functions strncpy, strncat, and strncmp, which operate on at most the first n characters of their argument strings. For example, strncpy(s,t,n) copies at most n characters of t to s. Full descriptions are in Appendix B.
action: /say Chapter 5: Pointers and Arrays; Exercise 5-6. Rewrite appropriate programs from earlier chapters and exercises with pointers instead of array indexing. Good possibilities include getline (Chapters 1 and 4), atoi, itoa, and their variants (Chapters 2, 3, and 4), reverse (Chapter 3), and strindex and getop (Chapter 4).
action: /say Chapter 5: Pointers and Arrays; Exercise 5-7. Rewrite readlines to store lines in an array supplied by main, rather than calling alloc to maintain storage. How much faster is the program?
action: /say Chapter 6: Structures; Exercise 6-1. Our version of getword does not properly handle underscores, string constants, comments, or preprocessor control lines. Write a better version.
action: /say Chapter 6: Structures; Exercise 6-2. Write a program that reads a C program and prints in alphabetical order each group of variable names that are identical in the first 6 characters, but different somewhere thereafter. Don’t count words within strings and comments. Make 6 a parameter that can be set from the command line.
action: /say Chapter 6: Structures; Exercise 6-3. Write a cross-referencer that prints a list of all words in a document, and for each word, a list of the line numbers on which it occurs. Remove noise words like ‘‘the,’’‘‘and,’’ and so on.
action: /say Chapter 6: Structures; Exercise 6-4. Write a program that prints the distinct words in its input sorted into decreasing order of frequency of occurrence. Precede each word by its count.
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<kr6-5>
action: /say Chapter 6: Structures; Exercise 6-5. Write a function undef that will remove a name and definition from the table maintained by lookup and install.
action: /say Chapter 6: Structures; Exercise 6-6. Implement a simple version of the #define processor (i.e., no arguments) suitable for use with C programs, based on the routines of this section. You may also find getch and ungetch helpful.
action: /say Chapter 7: Input and Output; Exercise 7-1. Write a program that converts upper case to lower or lower case to upper, depending on the name it is invoked with, as found in argv[0].
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<kr7-2>
action: /say Chapter 7: Input and Output; Exercise 7-2. Write a program that will print arbitrary input in a sensible way. As a minimum, it should print non-graphic characters in octal or hexadecimal according to local custom, and break long text lines.
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<kr7-3>
action: /say Chapter 7: Input and Output; Exercise 7-3. Revise minprintf to handle more of the other facilities of printf.
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<kr7-4>
action: /say Chapter 7: Input and Output; Exercise 7-4. Write a private version of scanf analogous to minprintf from the previous section.
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<kr7-5>
action: /say Chapter 7: Input and Output; Exercise 7-5. Rewrite the postfix calculator of Chapter 4 to use scanf and/or sscanf to do the input and number conversion.
action: /say Chapter 7: Input and Output; Exercise 7-6. Write a program to compare two files, printing the first line where they differ.
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<kr7-7>
action: /say Chapter 7: Input and Output; Exercise 7-7. Modify the pattern finding program of Chapter 5 to take its input from a set of named files or, if no files are named as arguments, from the standard input. Should the file name be printed when a matching line is found?
action: /say Chapter 7: Input and Output; Exercise 7-8. Write a program to print a set of files, starting each new one on a new page, with a title and a running page count for each file.
action: /say Chapter 7: Input and Output; Exercise 7-9. Functions like isupper can be implemented to save space or to save time. Explore both possibilities.
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<kr8-1>
action: /say Chapter 8: The UNIX System Interface; Exercise 8-1. Rewrite the program cat from Chapter 7 using read, write, open, and close instead of their standard library equivalents. Perform experiments to determine the relative speeds of the two versions.
action: /say Chapter 8: The UNIX System Interface; Exercise 8-2. Rewrite fopen and _fillbuf with fields instead of explicit bit operations. Compare code size and execution speed.
action: /say Chapter 8: The UNIX System Interface; Exercise 8-3. Design and write _flushbuf, fflush, and fclose.
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<kr8-4>
action: /say Chapter 8: The UNIX System Interface; Exercise 8-4. The standard library function int fseek(FILE *fp, long offset, int origin) is identical to lseek except that fp is a file pointer instead of a file descriptor and return value is an int status, not a position. Write fseek. Make sure that your fseek coordinates properly with the buffering done for other functions of the library.
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<kr8-5>
action: /say Chapter 8: The UNIX System Interface; Exercise 8-5. Modify the fsize program to print the other information contained in the inode entry.
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<kr8-6>
action: /say Chapter 8: The UNIX System Interface; Exercise 8-6. The standard library function calloc(n,size) returns a pointer to n objects of size size, with the storage initialized to zero. Write calloc, by calling malloc or by modifying it.
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<kr8-7>
action: /say Chapter 8: The UNIX System Interface; Exercise 8-7. malloc accepts a size request without checking its plausibility; free believes that the block it is asked to free contains a valid size field. Improve these routines so they make more pains with error checking.
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<kr8-8>
action: /say Chapter 8: The UNIX System Interface; Exercise 8-8. Write a routine bfree(p,n) that will free any arbitrary block p of n characters into the free list maintained by malloc and free. By using bfree, a user can add a static or external array to the free list at any time.
action: /say Learn C The Hard Way is an online book that should be avoided. It does not teach you C, but rather shows how C might work on a specific implementation. It contains numerous errors, bad examples and absurd arguments. See http://hentenaar.com/dont-learn-c-the-wrong-way and https://kellett.im/a/hardway
action: /say "Undefined reference" is a linker error. It's not a compile error. #includes don't help. You did not define the thing in the error message; you forgot to link the file that defines it; you forgot to link to the library that defines it; or, if it's a static library, you have the wrong order on the linker command line. Check which one. (Note that some linkers call it an unresolved external.)
action: /say This channel is not a substitute for a C book, we are not here to teach you C. Please learn C by working through a C book, and we'll be glad to assist you during your endeavor.
action: /say Learning C should be done gradually by following a C learning resource. By taking on projects you're not ready for you are not learning C and you waste a lot of time while getting frustrated with your progress.
action: /say The term "libc" is commonly used as a shorthand for the "standard C library", a library of standard functions that can be used by all C programs (and sometimes by programs in other languages).
action: /say There is no "local" scope in C. There are four kinds of scopes: function, file, block, and function prototype. A variable that appears inside of a function has block scope, which terminates at the end of the block.
action: In computer science, a lock is a synchronization mechanism for enforcing limits on access to a resource in an environment where there are many threads of execution
action: a signed integer data type, at least 32 bits wide, which must be able to represent (at least) all the integers in the range -2147483647 to +2147483647. Its lowest value, LONG_MIN, and highest value, LONG_MAX, are defined in <limits.h>
action: /say long long is a signed integer data type, at least 64 bits wide, which must be able to represent (at least) all the integers in the range -9223372036854775807 to +9223372036854775807. Its lowest value, LLONG_MIN, and highest value, LLONG_MAX, are defined in <limits.h>
action: /say If everything remotely "low level" were to automatically become associated with C, ##C would be flooded with tonnes of irrelevant questions about assembly and hardware.
action: /say An lvalue is an expression that potentially designates an object. When its value is used, it is converted to the value stored in its deisgnated object. Only modifiable lvalues can be assigned to; these include non-const variables and pointer dereferences.
action: int main(int argc, char *argv[]); or int main(int argc, char **argv); or int main(void); or some other implementation-defined prototype; See also ''argc'' and ''argv''; the standard entry point to C programs
action: /say It's better to use the object instead of the type as argument to sizeof when allocating. int *p; p = malloc(sizeof *p); is preferable to p = malloc(sizeof (int)); because you can then later change p to long *p or some other type without having to worry about maintaining or forgetting to change the malloc.
action: /say T *p = malloc(sizeof *p) is a much more robust idiom than T *p = malloc(sizeof (T)) because there is no chance of the sizeof (T) failing to match up with the T that was used to declare p. It's also more concise and easier to read.
action: If you are using OS that tries to be POSIX-compliant, or if such OS is target platform, use POSIX manpages: `emerge man-pages-posix` in Gentoo; `apt-get install manpages-posix manpages-posix-dev` in Debian or Ubuntu; in Windows download man-pages-posix from https://tinyurl.com/man-pages-posix or download the POSIX from http://pubs.opengroup.org/onlinepubs/9699919799/download/
action: /say Manuals document the implementation-specific behaviors and properties that are associated with a given implementation. For learning C, it is instead recommended to consult with a C book or the C standard.
action: /say Meaningless initializers are default initial values that act as a safety measure to avoid accessing uninitialized objects. This 'safety measure' doesn't fix your program and it severely reduces the capability to diagnose bugs. http://www.iso-9899.info/wiki/Meaningless_Initializers
action: /say The structure of computer memory and how it is utilised is something with which all programmers should be familiar. See Drepper's paper: What Every Programmer Should Know About Memory: http://www.akkadia.org/drepper/cpumemory.pdf
action: /say Not a C question. Your question is not specific to the C programming language. Standard C does not know nor care about colors, mice, windows, keyboards, networks or any other system-specific things. Please tell us what OS, compiler, tools or libraries you are using/abusing; or find the appropriate channel.
action: /say \n represents an implementation-defined character value, which is translated to and from the system end-of-line character sequence when written to or read from a stream in text mode.
action: /say That is not a C issue. This channel exists for discussion of the Standard C Language itself; not tools such as Makefiles, IDEs, compilers (see ##workingset for these things) or random libraries (including OS-specific ones such as POSIX or Windows; see ##posix or #winapi).
action: /say Null pointers are pointer values that are guaranteed to compare equal to 0 and to other null pointers, and not to point at any object or function.
action: defined as as a quantity of eight bits, typically used to represent one ASCII character, a signed integer from -128 to 127 or an unsigned integer from 0 to 255. On most platforms used today a byte has the same size as an octet.
action: /say For discussion not related to standard C, please go to ##c-offtopic. This includes discussion about non-standard libraries, operating systems, cats, video games, cars, chess, etc.
action: /say A pointer to a string is a pointer to its initial (lowest addressed) character. The length of a string is the number of bytes preceding the null character and the value of a string is the sequence of the values of the contained characters, in order.
action: /say POSIX is the Portable Operating System Interface, <http://pubs.opengroup.org/onlinepubs/9699919799/>. ##posix exists; please consider taking your related questions there.
action: the order the compiler uses to evaluate C expressions. See http://softkorner.wordpress.com/2011/09/21/precedence-of-c-operators/ for a table of operator precedence and associativity
action: /say There's little need to make generalizations about people who program with C. Some have interesting prejudices, others don't. In any case it will depend on the individual, and not the fact that they have a preference for a particular language.
action: pseudo-random number generator, #include <stdlib.h>, int rand(void); returns the next number in the sequence in the range [0,RAND_MAX], see http://www.iso-9899.info/man?rand and http://www.azillionmonkeys.com/qed/random.html
action: /say Due to the nature of undefined/implementation-specific/unspecified behavior, testing random code is not a adequate way of determining if something really does work.
action: "a pointer type may be derived from a function type, an object type, or an incomplete type, called the referenced type. A pointer type describes an object whose value provides a reference to an entity of the referenced type. A pointer type derived from the referenced type T is sometimes called ``pointer to T''. The construction of a pointer type from a referenced type is called ``pointer type derivation''."
action: /say C does not have pass-by-reference or "heavy" references like C++ or some other languages do. C does have a definition of references that is probably not what you want or need to know about, see: referencedtype
action: a storage-class specifier for an object that suggests that access for the object be as fast as possible. The extent to which the suggestion is effective is implementation defined. Whether or not addressable storage is actually used, the address of any part of an object declared with storage-class specifier register cannot be computed.
action: /say If you have a question about accessing registers in C, please don't ask us. Standard C has no way of manipulating hardware registers. We don't know what compiler or platform you're using. You should be reading the documentation instead.
action: a type qualifier, which may only be used with a pointer type, and which requires that objects referenced through such a pointer must be made through a single pointer value, i.e., no aliases / pointers into other parts of the object are allowed
action: /say Read the @#&ing Book - Your primary guide for learning C should be a good book (see http://www.iso-9899.info/wiki/Books). You must not expect to become a proficient C programmer just from reading crappy online `tuts', staring at other people's code, and/or boring us to death by asking dozens of exceedingly trivial questions.
action: a function that can be unsafe and unproductive - "It's nearly impossible to do decent error recovery with scanf; usually it's far easier to read entire lines (with fgets or the like), then interpret them, either using sscanf or some other techniques." - See http://www.eskimo.com/~scs/C-faq/q12.20.html
action: /say It looks like the !scanf factoid was unsuccessful at convincing you not to use scanf(). scanf() isn't really that stupid, providing you know how to use it correctly. Chris Torek explains some problems with the way scanf() is commonly used and provides methods of solving those problems here: http://bytes.com/topic/c/answers/215517-warning-against-scanf#post840862
action: /say Please avoid Herbert Schildt's C books. See http://www.seebs.net/c/c_tcn4e.html and http://www.lysator.liu.se/c/schildt.html -- Other stuff to avoid: http://www.iso-9899.info/wiki/Main_Page#Stuff_that_should_be_avoided
action: /say Evaluation of an expression may produce side effects. At certain specified points in the execution sequence called sequence points, all side effects of previous evaluations shall be complete and no side effects of subsequent evaluations shall have taken place.
action: packing structures, usually portably for later extraction: see man 3 xdr as well as http://tpl.sourceforge.net/ and http://www.leonerd.org.uk/code/libpack/
action: a signed integer data type, at least 16 bits wide, which must be able to represent (at least) all the numbers in the range -32767 to +32767. Its lowest value, SHRT_MIN, and highest value, SHRT_MAX, are defined in <limits.h>
action: an unsigned integer type which is the result type of the sizeof operator. A size_t variable can store the size of any object. C90: printf("%lu\n", (unsigned long)sizeof a); C99: printf("%zu\n", sizeof a);
action: /say The sizeof operator yields a size_t, that is the size (in bytes) of its operand, which may be an expression or the parenthesized name of a type. e.g. `sizeof expr` and `sizeof (int)`. That expression is not evaluated unless it is a variable-length array. sizeof does not have function call semantics; don't confuse people by writing it with function call syntax.
action: /say The sscanf function is similar to scanf, except that its input comes from a string instead of a stream. fgets is commonly used prior to sscanf to provide a simple approach which doesn't leave unmatched bytes on the stream, unlike scanf. Note that sscanf's and sprintf's format specifiers are not perfectly reflective, and that it is possible for fgets to fetch part of a line.
action: /say The ssize_t type is not a C standard type, it is part of POSIX. Its required range is [-1, 32767] and it's described as: "Used for a count of bytes or an error indication"
action: /say C does not require implementations to use stacks or heaps. Please refer to the actually defined storage durations, which are four: allocated, automatic, thread and static.
action: C89/C90 draft: http://port70.net/~nsz/c/c89/c89-draft.html - C99 + TC1,2,3 working paper: http://open-std.org/JTC1/SC22/WG14/www/docs/n1256.pdf - C11 draft: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf - Quick C library reference: http://goo.gl/n3TYMD - An explanation of all C standards: http://clc-wiki.net/wiki/The_C_Standard
action: used if the function/variable should be limited to one source file, at translation unit scope; variables of this storage class are initialised to zero; variables of this storage class which are declared in functions maintain their value between calls to the function
action: /say For a list of links to C standards, use the `standard` factoid; for citing the C99 standard, use `c99std`; for citing the C11 standard, use `c11std`
action_with_args: /say Standard C has no notion of '$args', so you must be talking about some specific OS, library, tool, implementation, architecture, et cetera. These are beyond the scope of this channel, which focuses on Standard C.
action: /say Will fflush(stdin) flush unread characters from the standard input stream? No! See http://www.c-faq.com/stdio/stdinflush.html and http://www.c-faq.com/stdio/stdinflush2.html
action: /say A "string" is a contiguous sequence of characters terminated by and including the first null character; http://www.iso-9899.info/wiki/String
action: /say If you are looking for support for a particular piece of software, you are in the wrong place. This channel exists for C programmers and those aspiring to be C programmers -- it is not a general software support channel.
action: /say ?: is called the conditional operator. Some clueless noobs refer to it as the ternary operator. This is not its name. While it is currently the only operator in C that takes three operands, this may not always be the case. It's still just a description of it, not its name. It's called the conditional operator!
action: /say The Rule, as Chris Torek calls it, is outdated, wrong and mostly useless. If you want to read it anyway, it says: "In a value context, an object of type "array N of T" (for suitable size N and element type T) becomes a value of type "pointer to T", pointing to the first element of that array, i.e., the one with subscript 0." http://web.torek.net/torek/c/pa.html
action: /say "Try It And See" may work in other languages, but not in C due to the nature of undefined behavior/unportable code. Such coding-by-experimentation often leads to situations such as "But it worked fine earlier!" and/or "But it worked on my machine!". https://goo.gl/jPWRA9
action: a three character sequence beginning with two question marks, intended to make using C possible on systems where the usual punctuators are missing, typically from keyboards. these sequence is replaced during phase 1 of translation and takes place even within quoted strings.
action: /say A source file together with all the headers and source files included is known as a preprocessing translation unit . After preprocessing, a preprocessing translation unit is called a translation unit. The separate translation units of a program communicate by (for example) calls to functions whose identifiers have external linkage, manipulation of objects whose identifiers have external linkage, or manipulation of data files.
action: /say Almost every "tutorial" on the web is written by a person who does not know C well. Would you learn C from such a person? Obtain a good C book (see ,books) and read it.
action: /say Blindly typedefing all structs "just because" is one of the greatest abuses of typedefs in C -- don't do this. Only typedef structs when they are supposed to be opaque types that are manipulated strictly via accessor/mutator functions. Never use typedef to create a pointer type.
action: a qualifier for integer data types, which renders them incapable of representing negative numbers but increases the number of positive values they can represent.
action: a variable length array: an array data structure of automatic storage duration whose length is determined at run time (instead of at compile time). Example: void foo(int n) { float arr[n]; }
action: /say A volatile-qualified object may be modified in ways unknown to the implementation or have other unknown side effects when accessed. Actions on such objects shall not be `optimized out` by an implementation or reordered except as permitted by the rules for evaluating expressions.
action: convert date and time to wide string, #include <wchar.h>, size_t wcsftime(wchar_t *ws, size_t maxlen, const wchar_t *format, const struct tm *timeptr); returns NULL if the conversion would succeed within maxlen wide characters otherwise the number of codes stored excluding the terminating null wide character, see http://www.iso-9899.info/man?wcsftime
action: convert wide character string to (narrow) character string (restartable), #include <wchar.h>, size_t wcsrtombs(char *s, const wchar_t **ws, size_t len, mbstate_t *ps); returns (size_t)-1 and stores EILSEQ in errno if a wide character is encountered that cannot be converted otherwise the number of bytes in the resulting sequence not including the terminating null character, see http://www.iso-9899.info/man?wcsrtombs
action: /say The XZ problem: You want to type XY but you forgot that you are typing on an unusual keyboard where the Z and Y keys are swapped for some reason.
action: the bitwise inclusive-OR assignment operator. The expression (x |= y) is equivalent to (x = x | y) except that the expression x is evaluated only once.
action: { return "/me pours a $sizes cup of Mississippi mud for @args" if "$no_coffee_for_you" =~ /$nick/i or grep { "$no_coffee_for_you" =~ /$_/i } @args; return "/call fact global coffee @args"; }
action: /say event not found -- These errors only happen in *interactive* shells when you run commands with ! in them with history expansion enabled. Run set +o histexpand (set +H) to disable it,and put it in your ~/.bashrc to disable it in future shell sessions, too. Regardless, it won't affect scripts.
action: /say In addition to having exec permission, the top of a script MUST have a #! line, called 'shebang' or 'hashbang'. It tells the kernel what program to run your script with. Make sure you adjust it to match where the appropriate version of Bash is installed on your system;. If your system does not have bash installed at /bin/bash you will likely have to adjust any scripts you receive.
action: /say cmd1 "`cmd2 \"$1\"`" -- An expression that has never been written in the history of mankind; because that would be correct; and those that don't know enough to not use backticks also by necessity don't know how to quote.
action: /say Either a comment, or in parameter expansion a count of something. ${#x} is the number of characters in $x. ${#x[@]} is the number of elements in the array 'x', and $# is the number of positional parameters.
action: /say In bash, $ means "Expand". It is NOT part of your variable name! You can expand "$variable" content, "$(command)" output or "$((arithmetic))" results.
action: /say Bash supports $"..." quoting syntax for locale-specific translation. If the current locale is C or POSIX, the dollar sign is ignored. If the string is translated and replaced, the replacement is double-quoted. See http://mywiki.wooledge.org/BashFAQ/098
action: /say $$ expands to the PID of the shell. In a ( ) subshell, it expands to the process ID of the original shell, not the subshell. (Bash 4.0 and above have BASHPID for that.)
action: /say bash has a special form of quoting, $'string' in which backslash-character combinations are expanded. For example, IFS=$' \t\n' or echo $'It\'s embedded!' http://mywiki.wooledge.org/Quotes
action: /say Command Substitution: "$(cmd "foo bar")" causes the command 'cmd' to be executed with the argument 'foo bar' and "$(..)" will be replaced by the *output*. See http://mywiki.wooledge.org/BashFAQ/002 and http://mywiki.wooledge.org/CommandSubstitution
action: /say $((...)) is an arithmetic substitution. After doing the arithmetic, the whole thing is replaced by the value of the expression. See <http://mywiki.wooledge.org/ArithmeticExpression>.
action: /say The command substitution $(cat file) can be replaced by the equivalent but faster $(< file).
created_on: 1228996478
enabled: 1
owner: iasc
rate_limit: 10
ref_count: 79
ref_user: nobody
type: text
<$(echo>
action: /say $(echo ...) and echo $(...) are both pointless. Drop the echo and $(), just write ...: rm "$(echo myfile)" -> rm myfile --- echo "$(df -h)" -> df -h; http://www.iki.fi/era/unix/award.html#echo
action: /say $- expands to the current option flags as specified upon invocation, by the set builtin command, or those set by the shell itself (such as the -i option).
created_on: 1296939190
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 42
ref_user: nobody
type: text
<$0>
action: /say $0 is like argv[0] in C. It's whatever the caller decides to put there. You can't rely on it. See http://mywiki.wooledge.org/BashFAQ/028 and http://www.bash-hackers.org/wiki/doku.php/scripting/posparams#the_first_argument
created_on: 1280242031
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 159
ref_user: nobody
type: text
<$1>
action: /say Positional parameters by example: echo "First parameter is $1, second is $2. You supplied $# of them. They will now all be copied to /tmp."; cp "$@" /tmp;
created_on: 1285668282
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 35
ref_user: nobody
type: text
<$?>
action: /say The special parameter ? (expanded by $?) holds the exit status of the last synchronous command.
created_on: 1390142801
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 213
ref_user: nobody
type: text
<$@>
action: /say The difference between $@ and $*: Without quotes (don't do this!), there is no difference. With double quotes, "$@" expands to each positional parameter as its own argument: "$1" "$2" ..., while "$*" expands to the single argument "$1c$2c...", where 'c' is the first character of IFS. You almost always want "$@" (QUOTED!). The same goes for arrays: "${array[@]}".
created_on: 1409667154
enabled: 1
owner: [arx]
rate_limit: 10
ref_count: 514
ref_user: nobody
type: text
<$[>
action: /say $[...] is an obsolete, deprecated syntax for math. Don't use it. Use $((...)) instead.
created_on: 1294676904
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 72
ref_user: nobody
type: text
<$_>
action: /say "$_" expands to the last argument to the previous command, after expansion (man bash, Special Parameters)
created_on: 1303506465
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 56
ref_user: nobody
type: text
<$dayjob>
action: /say DAYJOB is a built-in variable for #bash, and is therefore capitalized
created_on: 1390438745
enabled: 1
owner: kurahaupo
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<$grep>
action: /say ''GREP="/usr/bin/grep -i"; $GREP $FILE'' -- Do NOT put command names or options in variables. Doing so is dangerous and buggy. Variables are containers for DATA. Either inline the command completely or use a *function* instead. http://mywiki.wooledge.org/BashFAQ/050
action: /say The SHELL environment variable is normally set to the login shell specified in the passwd database (/etc/passwd) when you log in. It does NOT reflect what shell you're currently in. For that, try: ps -p $$
action: /say Avoid short and meaningless variable names. Use your variable names to communicate what they hold: the more your naming says, the better your code reads. $file, not $f. $remoteHost, not $h. One convention is to use singular words for regular variables, plural for arrays and the first letter of the array for indexes in that array (eg. for f in "${!files[@]}" / for file in "${files[@]}").
created_on: 1376535238
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<$var>
action: /say $var is NOT a variable. var is a variable and $var is the EXPANSION of that variable. bash replaces it by the contents of the variable var.
created_on: 1209547390
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<${>
action: /say Without curly braces parameter expansions refer to the longest valid variable name or shortest positional parameter. "${var}bar" expands the parameter named "var" while "$varbar" expands "varbar". "$123" references argv[1] and "${123}" references argv[123]. Braces are requried for parameters > 9, special PEs, and array expansions: ${10}, ${var##pat}, ${arr[5]}. BRACES AREN'T A SUBSTITUTE FOR QUOTES!
action: /say See !faq 6 for indirect variables, or !faq 5 for listing array indices.
created_on: 1425074604
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<${#>
action: /say see !faq length for variables and !faq 5 for array varibles
created_on: 1261337435
enabled: 1
owner: irc2samus
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<${$>
action: /say The correct syntax for parameter expansion is ${varMODIFIER} not ${$varMODIFIER}. Remove that second $.
created_on: 1179319977
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 10
ref_user: nobody
type: text
<${${>
action: /say ${x}, ${x%y}, ${x:y:z}, ... are parameter expansions. x needs to be a parameter. you can't 'nest' them like ${${x#y}%z} because ${x#y} is an expansion (a string), not a parameter.
action: /say If you put the control operator & at the end of a command, e.g. ''command args &'', the shell executes the command in the background in a subshell. The shell does not wait for the command to finish, and the return status is 0. Pid of the last backgrounded command is available via the special variable $!
created_on: 1272476781
enabled: 1
owner: ferret
rate_limit: 10
ref_count: 149
ref_user: nobody
type: text
<&&>
action: /call ||
created_on: 1372353346
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 115
ref_user: nobody
type: text
<&&:>
action: /say cmd && : prevents set -e from killing the shell, and keeps intact the exit code of cmd
created_on: 1441042578
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<&&if>
action: /say Beware: ''a && b || c'' is NOT THE SAME as ''if a; then b; else c; fi''. The former will run 'c' if EITHER 'a' or 'b' fails. The if will run 'c' ONLY if 'a' fails.
created_on: 1375297234
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<&&||>
action: /say foo && bar || baz is not equivalent to 'if foo; then bar; else baz; fi'. In the former case, baz will happen if *either* foo *or* bar return false. In the latter case, baz will only trigger if foo returns false, regardless of the exit code for bar. See http://mywiki.wooledge.org/BashPitfalls
created_on: 1276419923
enabled: 1
owner: \amethyst
rate_limit: 10
ref_count: 48
ref_user: nobody
type: text
<&;>
action: /say '&;' is always wrong. So is '& ;'. If you want to run things in the background in a compact one-liner, omit the ';' entirely and simply use '&' between commands. for f in ./*; do my_command "$f" & done - see http://mywiki.wooledge.org/BashPitfalls#pf21
created_on: 1397244466
enabled: 1
owner: fr33load3r
rate_limit: 10
ref_count: 94
ref_user: nobody
type: text
<&>>
action: /say &> is a bash-specific feature. «&>file» is equivalent to «>file 2>&1». There is no &>> until Bash4. Use «>>file 2>&1» instead. We recommend not using &> or &>> in scripts, because it will break some valid scripts (see !badredir), and is an unintuitive syntax for beginners.
created_on: 1432128216
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 75
ref_user: nobody
type: text
<&>>>
action: /say ''&>file'' is equivalent to ''>file 2>&1'' and is bash/ksh specific. In bash 4, there is also ''&>>file''. For portability, it is a good idea to just write it out fully.
created_on: 1426602961
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 14
ref_user: nobody
type: text
<'>
action: /say Single quotes (') cause everything between them to be taken literally by bash. If you want to embed a ' inside a '...', write it as the four characters, '\'': echo 'It'\''s a blast!'
created_on: 1277222888
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 243
ref_user: nobody
type: text
<''>
action: /say '' is preferred for quoting code in #bash, because it has no semantic meaning for the shell; someone can copy-and-paste ''foo'' or the contents within, and the meaning to the shell is the same either way.
created_on: 1357254500
enabled: 1
owner: nDuff
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<(>
action: /call ()
created_on: 1357143428
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 92
ref_user: nobody
type: text
<((>
action: /say ((...)) is an arithmetic command, which returns an exit status of 0 if the expression is nonzero, or 1 if the expression is zero. Also used as a synonym for "let", if side effects (assignments) are needed. See <http://mywiki.wooledge.org/ArithmeticExpression>.
created_on: 1293585738
enabled: 1
owner: prince_jammys
rate_limit: 10
ref_count: 358
ref_user: nobody
type: text
<()>
action: /say Commands ran inside parenthesis are executed in a subshell. Useful for cd'ing into a directory without needing to figure out how to back out. See http://mywiki.wooledge.org/SubShell
action: /say Tools generally consider an argument that begins with a - as an option. To pass a filename that begins with a -, prefix it with its path: rm ./-foo. Also: rm -- -foo (see !--). - alone can also mean stdin.
created_on: 1379918390
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 28
ref_user: nobody
type: text
<-->
action: /say The special option -- means "end of options" to every POSIX command except echo and test. E.g., mv -- *.png /somedir # see also http://wiki.bash-hackers.org/dict/terms/end_of_options
created_on: 1316030679
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 148
ref_user: nobody
type: text
<-9>
action: /say Do NOT use SIGKILL (kill -9) to terminate processes. All processes will terminate in response to the default SIGTERM. If they don't terminate instantly, that's because they're busy cleaning up. If you interrupt them, you break them. See http://stackoverflow.com/a/690631/347411
created_on: 1384960490
enabled: 1
noembed: 1
owner: lhunath
rate_limit: 10
ref_count: 76
ref_user: nobody
type: text
<-c>
action: /say bash -c 'bash commands to execute' "$0" "$1" "$2" ... Since "$0" is typically unused, it is often set it to something arbitrary like _
created_on: 1254411920
enabled: 1
owner: \amethyst
rate_limit: 10
ref_count: 12
ref_user: nobody
type: text
<-e>
action: /call set-e
created_on: 1319454580
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 70
ref_user: nobody
type: text
<-exec_>
action: /say find ... -exec sh -c 'blah "$1"' _ {} \; # When invoked with -c, any POSIX shell (including bash) uses the first positional parameter as "$0". '_' is a dummy value, so the passed filename becomes "$1". it could be anything. of course "$0" could be used, but when using -exec {} +, "$@" does not include "$0"
created_on: 1331919289
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<-f>
action: /say Do you actually need that -f in that command? If there a reason you are using it? Or is it just there because of habit? Do you actually know what the -f does and do you even want it there?
created_on: 1430612710
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<-nt>
action: /say [ f1 -nt f2 ] True if file1 is newer (mtime) than file2 *or* if file1 exists and file2 does not.
created_on: 1182378035
enabled: 1
owner: redduck666
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<-r>
action: /say Always use read with the -r option, otherwise backslashes are special. http://wiki.bash-hackers.org/commands/builtin/read#read_without_-r
created_on: 1410998544
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<-u>
action: /call set-u
created_on: 1408798435
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<-x>
action: /call set-x
created_on: 1434697012
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 409
ref_user: nobody
type: text
<08>
action: /call august
created_on: 1312544942
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<10q>
action: /say Isn't anyone going to thank me for all my hard work?
created_on: 1299792689
enabled: 1
owner: kwtm
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<1line>
action: /call in1line
created_on: 1407527470
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 22
ref_user: nobody
type: text
<256colormap>
action: /say E=echo\ ;P=printf\ ;M=$'\e[0m';a(){ $P"\e[38;5;2${z}5;48;5;${1}m %4d $M" $1;};Z=$E$M;for i in 16 93 160;do ((r=(n=\!n)*2-1));for((x=0;x<6;x++,i+=r)) do for((j=0;L=(i+(R=(j/6?17-j:j))*6),z=(R%6>1?3:5),j<12;j++))do a $L;done;$E;done;done;z=5;for i in {0..23};do a $[i+232];((i==11))&&$Z;done;for i in {0..15};do ((i==8||\!i))&&$P'\n%*s' 12;a $i;done;$E
created_on: 1420424787
enabled: 1
owner: i336_
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<2>&1>
action: /say Making sense of the copy descriptor operator: http://wiki.bash-hackers.org/scripting/copydescriptor
created_on: 1271714518
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 76
ref_user: nobody
type: text
<2d>
action: /say Bash doesn't support multi-dimensional arrays. Common substitutes are: 1. directories, eg. firstName=$(<~/.myscript/names/first/"$person"); 2. shared indexes, eg. name="${firstNames[person]} ${lastNames[person]}"; 3. merge in associative key, eg. declare -A names=( ["0-first"]=John ["0-last"]=Doe ["1-first"]=Jane ["1-last"]=Doe ); 4. primes, eg. names[i*29 + j*31]=value
action: /say !1 but without backslash interpretation or stripping of leading/trailing spaces: while read -r; do my-command "$REPLY"; done <inputfile -- or for POSIX shell: while IFS= read -r line; do my-command "$line"; done <inputfile
created_on: 1355931952
enabled: 1
owner: saveTheWorld
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<2steps>
action: /say Step 1: Figure out want you want to do. Step 2: Do it. The first step is the hard part.
action: /say This character sequence causes greycat to smile. Use with caution.
created_on: 1303248798
enabled: 1
owner: kwtm
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<:->
action: /say ${parameter:-word} Use Default Values. If parameter is unset or null, the expansion of word is substituted.
created_on: 1409271629
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<:=>
action: /say ${parameter:=word} Assign Default Values. If parameter is unset or null, the expansion of word is assigned to parameter.
created_on: 1407542483
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<;>
action: /say The ";" character is used to separate between commands. It does the (almost) exact same thing that <ENTER> does in a shell or a newline in a script.
created_on: 1426717129
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<;&>
action: /call ;;
created_on: 1338252255
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 17
ref_user: nobody
type: text
<;;>
action: /say ;; signifies the end of a case list. ;& makes it fall through to the next list. ;;& makes it fall through to the next list if the pattern matches.
created_on: 1338252194
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<;;&>
action: /call ;;
created_on: 1338252260
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<<>
action: /call redir
created_on: 1236006930
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 55
ref_user: nobody
type: text
<<(>
action: /say Process Substitution: <(command) or >(command) is replaced by a FIFO or /dev/fd/* entry. Basically shorthand for setting up a named pipe. See <http://mywiki.wooledge.org/ProcessSubstitution>. Example: diff -u <(sort file1) <(sort file2)
created_on: 1403286314
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 357
ref_user: nobody
type: text
<<()>
action: /say Process Substitution >(command ...) or <(...) is replaced by a temporary filename. Writing or reading that file causes bytes to get piped to the command inside. Often used in combination with file redirection: cmd1 2> >(cmd2). See http://mywiki.wooledge.org/ProcessSubstitution http://mywiki.wooledge.org/BashFAQ/024
created_on: 1376318052
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 81
ref_user: nobody
type: text
<<<>
action: /say Here documents. cat <<EOF followed by several lines of text, followed by the literal string EOF on a new line, NOT indented. The portion between the EOFs is passed to the command as standard input. If 'EOF' is 'quoted', substitutions WON'T be done; otherwise they are. See <<- for the indented variety.
created_on: 1204959411
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 254
ref_user: nobody
type: text
<<<(>
action: /call <<()
created_on: 1395865286
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<<<()>
action: /say command < <(othercommand) # Same thing as ''othercommand | command'' but without subshelling 'command'. Uses file redirection (<) to redirect a file created by process substitution (<()). The space between < and <(..) is important to avoid ambiguity (is it a heredoc, is it a redirected PS?).
created_on: 1395865667
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<<<->
action: /say Indented Here documents. Here documents started with <<- will ignore preceding tabs on each line, allowing you to indent your here documents nicely. Refer to << for general information on Here documents. Note that only TABs will work - spaces will not. Some editors can replace the TAB character with spaces, so be careful.
created_on: 1426300221
enabled: 1
owner: llua
rate_limit: 10
ref_count: 71
ref_user: nobody
type: text
<<<<>
action: /say Here strings. Similar to here documents: The word after <<< and a newline are passed to the standard input of a command. Syntax: ''command <<< "some sentence"'' (Like ''echo "some sentence" | command'', but without the overhead of the subshell)
created_on: 1228905237
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 277
ref_user: nobody
type: text
<<<<$(>
action: /say <<<"$(command)" is pointless. It creates multiple temp files, requires the entire command to run before passing it to stdin, and removes trailing newlines from the command's output. Without the quotes, it's even worse; wordsplitting occurs and all whitespace gets squeezed to single spaces. Process substition was created for doing this efficiently and correctly. See http://mywiki.wooledge.org/ProcessSubstitution
created_on: 1333171490
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 19
ref_user: nobody
type: text
<<>>
action: /say <>foo is the same as 0<>foo. To redirect both stdin and stdout to the same file, you need <>foo >&0
action: /say If you're using $? and not immediately assigning it to a variable, you're DoingItWrong. Either you're testing it immediately (in which case you don't need $? at all, see ![$? ) or else you're doing something else and then using it, in which case the value of $? will be changed before you use it.
created_on: 1422998875
enabled: 1
owner: kurahaupo
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<==>
action: /say The == operator is used to test numbers for equality in ((arithmetic expressions)). In BASH and ksh it is the same as = in [[ ]]. It should not be used in the POSIX / Bourne compatible test or [ ], as this will not work in other shells.
created_on: 1285106199
enabled: 1
noembed: 1
owner: ferret
rate_limit: 10
ref_count: 46
ref_user: nobody
type: text
<>>
action: /say Use > to write redirect STDOUT to a file: ls > myFileList. See !redir
created_on: 1222624666
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 96
ref_user: nobody
type: text
<>&>
action: /say >&word where word is a number or - is FD duplication or closing. A plain >& or >&word (word not numeric or -) is just like &> -- cmd >& file is equivalent to cmd >file 2>&1 but the former is bash- and csh-only.
created_on: 1319317790
enabled: 1
owner: greycat|home
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<>(>
action: /call <(
created_on: 1236007616
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 73
ref_user: nobody
type: text
<>()>
action: /call >(
created_on: 1285771573
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 20
ref_user: nobody
type: text
<>>>
action: /say Use >> to append to a file and prevent the original contents from being erased. See !redir
created_on: 1222624659
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 69
ref_user: nobody
type: text
<>sed>
action: /say Ask in #sed.
created_on: 1200547743
enabled: 1
owner: igli
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<>|>
action: /say Redirect stdout, like > but ignores noclobber (set -C). See http://wiki.bash-hackers.org/syntax/redirection
created_on: 1423467671
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<?>
action: /say A question mark indicates a sentence is a question. When you see a sentence directed at you terminated with this symbol, somebody has asked you a question and is waiting for you to answer it.
created_on: 1402671387
enabled: 1
last_referenced_in: deadsoul
last_referenced_on: 1446177502.40201
noembed: 1
owner: lhunath
rate_limit: 10
ref_count: 19
ref_user: DeaDSouL!~deadsoul@94.29.129.54
type: text
<@>
action: /say The positional parameters can be used like a named array, sort of. "$@" is just like "${array[@]}". PE works too: "${@:2}", or "${@:(-1)}", or "${@/#-/}", etc. However, you can't set or unset single positional params.
action: /say [ or test is the POSIX test command. It can do simple tests on files and strings. In bash, you should use the more powerful [[ instead and ban [ for sake of consistency. [[ can do pattern matching, is faster and safer to use. http://mywiki.wooledge.org/BashGuide/TestsAndConditionals http://mywiki.wooledge.org/BashFAQ/031
created_on: 1393469285
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 358
ref_user: nobody
type: text
<[$?>
action: /say Don't do this: ``mycommand; if [ $? -eq 0 ]'' -- You're running the [ command and checking its exit code to test whether "mycommand"'s exit code is 0. That's a pointless operation, test mycommand directly: ``if mycommand''
created_on: 1403808404
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 145
ref_user: nobody
type: text
<[-a>
action: /say The classic test command's -a and -o operators, as well as controlling precedence using ( and ) cause many problems and ambiguities, are not portable, and are unsafe with user input. They are all marked as obsolescent by POSIX. If coding for Bash, Ksh, or Zsh, [[ is *highly* preferred over [. See: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html#tag_20_128_16
created_on: 1331097167
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 30
ref_user: nobody
type: text
<[-o>
action: /call [-a
created_on: 1347065450
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<[:>
action: /say Character classes like [a-z] or [A-Z0-9] may behave strangely in non-POSIX locales. If you want your script to work locale-wise, use [[:lower:]] or [[:upper:][:digit:]] instead. Remember to always quote your character classes, as they may be expanded by the shell as file globs. See also !locale
created_on: 1289302978
enabled: 1
owner: cthuluh
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<[<>
action: /say to get STRING comparison you must escape the < in [ a \< b ] otherwise "< b" is intrepreted as a redirection from the file "b". There is no problem with [[ a < b ]]. The same applies to [ a \> b ]
created_on: 1182865801
enabled: 1
owner: redduck666
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<[[>
action: /say [[ is a bash keyword similar to (but more powerful than) the [ command. See <http://mywiki.wooledge.org/BashFAQ/031> and <http://mywiki.wooledge.org/BashGuide/TestsAndConditionals>. Unless you're writing for POSIX sh, we recommend [[.
created_on: 1273072403
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 752
ref_user: nobody
type: text
<[[$?>
action: /call [$?
created_on: 1332920944
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<[vs[[>
action: /say '[', also known as 'test' is the POSIX variant of [[. [ does NOT support ==, =~, &&, ||, glob pattern matching; unquoted > and < will do file redirection instead of comparison, etc. See http://mywiki.wooledge.org/BashFAQ/031
created_on: 1244096499
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<\0>
action: /say ASCII zero, the null byte, aka 'NUL' is the best delimiter for lists of strings (eg. file names). However, there isn't much you can do with it in portable scripts. Bash can read null-byte delimited input with "while IFS= read -d ''; do ... ". Bash cannot store or pass a null byte as parameter. *Unportable* versions of the following utilities can work with NULs: find, sort, xargs, and sed.
created_on: 1216931860
enabled: 1
owner: prince_jammys
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<\<>
action: /say The symbols \< and \> respectively match the empty string at the beginning and end of a word.
created_on: 1387543772
enabled: 1
owner: juanmabc
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<\<\>>
action: /say The symbols \< and \> respectively match the empty string at the beginning and end of a word.
action: /say The symbols \< and \> respectively match the empty string at the beginning and end of a word.
created_on: 1387543778
enabled: 1
owner: juanmabc
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<\r>
action: /call cr
created_on: 1318766724
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 23
ref_user: nobody
type: text
<\w>
action: /call prompt
created_on: 1300816057
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<]>
action: /call [
created_on: 1236007699
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<]]>
action: /call [[
created_on: 1236007711
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<^$()>
action: /say You do not need $() to "run stuff". $(command); $(command); $(command) is just plain WRONG. Bash runs every line as a command. $() is ONLY used to capture the OUTPUT of the command and INLINE it (expand it in-place). Use command; command; command instead.
created_on: 1298537848
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<^c>
action: /say Bash 4.0 started echoing ^C when you press SIGINT in editing mode, which is very annoying. To revert to previous behavior in bash 4.1: echo 'set echo-control-characters off' >> ~/.inputrc # (No known way to fix it in bash 4.0.)
action: /say The parameter _ is often used as a dummy variable in read commands to discard unwanted fields. It should not be used this way in portable scripts due to known conflicting usages in several common shells. See also: $_
created_on: 1407970806
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 42
ref_user: nobody
type: text
<_matrix_>
action: /say Follow the white rabbit...
created_on: 1188335214
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<`>
action: /say The backquote (`) is used in the old-style command substitution, e.g. foo=`command`. The foo=$(command) syntax is recommended instead. Backslash handling inside $() is less surprising, and $() is easier to nest. See http://mywiki.wooledge.org/BashFAQ/082
action: /say The infamous "Advanced" Bash Scripting Guide should be avoided unless you know how to filter out the junk. It will teach you to write bugs, not scripts. In that light, the BashGuide was written: http://mywiki.wooledge.org/BashGuide
action: /say adu(1) - a date utility - source code at http://twkm.freeshell.org/adu.tar.Z
created_on: 1213292230
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<advanced>
action: /say You are? Good then could you fix the bugs in bash? You know the list of course, since you *are* advanced. Thanks for your help. Oh and edit the wiki! :D
action: /say An alias is a small in-line command name text replacement. They are not commands and cannot take arguments. Only use aliases for expanding things like default command switches: alias l='ls -l'. For everything else, use a function instead: del() { mv -i "$@" ~/.trash; }
created_on: 1427822613
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 353
ref_user: nobody
type: text
<aliases>
action: /say Aliases suck. They don't work in scripts. They can't take arguments. They have special evil magical powers that break all expectations. See http://mywiki.wooledge.org/BashFAQ/080 for starters.
created_on: 1280234894
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 22
ref_user: nobody
type: text
<alphabet>
action: /say 3# for _ in $(echo <(: {1..26})); do printf \\"$(printf %o $((128-${_##*/})))"; done; echo
created_on: 1431989300
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<altgr>
action: /say In X-windows, AltGr is a notional key which can be bound to a regular key on a keyboard, so you can use that key somewhat like a "shift" key to access additional symbols such as ¬ ¥ ÷ ¿ ½ €. Usually it is bound to one of the "windows" or "alt" keys.
created_on: 1383888104
enabled: 1
owner: kurahaupo
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<ambiguity>
action: /say Ambiguity is bad! It makes bad... stuff... happen! Badly!
created_on: 1156190461
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<anal>
action: /say "older, or emotionally damaged brains that have trouble dealing with the evolving nature of language and communication will condemn new constructs as evidence of incompetence. All it really means is they are slowly fading from relevance."
action: /say "Anarchists are those who advocate the absence of the state, arguing that __common sense__ would allow for people to come together in agreement to form a functional society" -- http://en.wikipedia.org/wiki/Anarchy#Anarchism
created_on: 1181111829
enabled: 1
owner: r00t
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<and>
action: /say Try faq foo and bar aka faq 79
created_on: 1284688041
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<another_way>
action: /say Yes, there's always another way. Write a script that produces random output and performs random file deletions/creations/renamings, and run it repeatedly until it produces the desired outcome.
action: /say If we're asking you questions, it's not to intentionally annoy or delay you. We're trying to find the best answer to your problem. Want a good solution? Patiently answer each of them to the best of your ability.
action: /say http://mikeash.com/getting_answers.html "Most of the time you'll be talking to people who know more about the subject at hand than you do (that's why you came to them for help in the first place, remember). As such, it pays to at least entertain the possibility that they know what they're talking about." Read the link and bear in mind we deal with that shit day in, day out.
created_on: 1183679425
enabled: 1
owner: igli
rate_limit: 10
ref_count: 30
ref_user: nobody
type: text
<applause>
action: /say zzZZzz. what who huh? oh... Yay. zzZZzz
created_on: 1260825218
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<arch>
action: /say Archlinux is usually taken as a l33t distro but the truth is that anyone who manages a rcfile is l33t-enough to deal with it :)
created_on: 1217270636
enabled: 1
owner: Samus_
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<arg:>
action: /say "(arg: N)" (N is any number) is what you get in emacs mode when you press ESC and then type a number. The NEXT thing you press after the number will be repeated N times. Silly emacs.
created_on: 1280926535
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<arg_max>
action: /call argmax
created_on: 1369946112
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<argmax>
action: /say The kernel constant ARG_MAX defines the maximum number of bytes that can be passed to exec(3). On Linux since libc 2.8, this value is determined dynamically based upon the system, and is not hardcoded. # http://www.in-ulm.de/~mascheck/various/argmax/
action: /say Add 7 to a variable: let a+=7; ((a+=7)); a=$((a+7)); See http://wooledge.org/mywiki/ArithmeticExpression
created_on: 1211897084
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 69
ref_user: nobody
type: text
<arithmetics>
action: /call math
created_on: 1332853588
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 12
ref_user: nobody
type: text
<array>
action: /say An array maps numbers to strings. Bash 4 also has associative arrays (maps strings to strings). http://mywiki.wooledge.org/BashSheet#Arrays http://mywiki.wooledge.org/BashFAQ/005 http://wiki.bash-hackers.org/syntax/arrays
action: /say "Ash" is ambiguous. It is a name shared by a huge family of Bourne-like shells. See: http://www.in-ulm.de/~mascheck/various/ash/ . Currently maintained examples include Dash and Busybox's ash (go to #uclibc for the latter).
created_on: 1355640304
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<ask>
action: /say If you have a question, please just ask it. Don't look for topic experts. Don't ask to ask. Don't PM! Don't ask if people are awake, or in the mood to help. Just ask the question straight out, and be patient waiting for an answer. http://mywiki.wooledge.org/NetEtiquette
action: /say "Assume makes an 'ass' of 'u' and 'me'"
created_on: 1181068753
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<attach>
action: /say To attach files to email in a script, use mutt or nail. If you are on a piece of shit legacy machine and have to use mail/mailx, see http://www.shelldorado.com/articles/mailattachments.html
action: /say August is the month when all your scripts break because you placed $(date +%m) in a variable and tried to do arithmetic with it, without removing the leading zeros. 08 is considered octal. Use $((10#$month)) to force decimal, or strip the zero.
created_on: 1283434611
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 203
ref_user: nobody
type: text
<auth>
action: /say Authentication is ENTIRELY a function of the application or system to which you are authenticating. THERE IS NO GENERAL WORKAROUND. If you are authenticating to MySQL, ask #mysql. If you want to automate ssh, see http://mywiki.wooledge.org/BashFAQ/069 . If you want to set users' passwords, see http://mywiki.wooledge.org/BashFAQ/078 .
created_on: 1302640271
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<authentication>
action: /call auth
created_on: 1325621809
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<autocd>
action: /say autocd moves to directories automatically without having to prepend them with ''cd'', it's available from bash4+.
action: /say We don't care about every trip to the potty that you make. Do not announce your aways publically. See http://sackheads.org/~bnaylor/spew/away_msgs.html
created_on: 1203498387
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 27
ref_user: nobody
type: text
<awk>
action: /say Check the topic of #awk and also http://www.grymoire.com/Unix/Awk.html -- awk questions belong to #awk. Note: If you are piping through more than one (grep|sed|awk), you're likely doing it wrong.
created_on: 1251905329
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<awk-v>
action: /say The correct way to get a shell variable into awk is with awk's -v flag, not by putting the $var into the awk code. var=foo; awk -v name="$var" 'BEGIN{print "Hello " name}'
created_on: 1397111810
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<awkquote>
action: /say To inject data into an awk script, pass the option -v "var=$data" and use var inside your awk code.
created_on: 1348086109
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<awkvar>
action: /call awkvars
created_on: 1309881022
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<awkvars>
action: /say Set an awk variable: awk ... -v foo="$bar" ... '$0 ~ foo'
created_on: 1309272711
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<b0>
action: /say The questioner will never tell you what they are really doing the first time they ask.
created_on: 1185921061
enabled: 1
owner: savetheWorld
rate_limit: 10
ref_count: 44
ref_user: nobody
type: text
<b1>
action: /say bashphorism 1: the questioner's first description of the problem/question will be misleading.
action: /say The newbie will always have some excuse for doing it wrong.
created_on: 1305128785
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 110
ref_user: nobody
type: text
<b21>
action: /say If^H^HWhen the newbie's question is ambiguous, the proper interpretation will be whichever one makes the problem the hardest to solve.
created_on: 1344895585
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 83
ref_user: nobody
type: text
<b22>
action: /say The newcomer will abuse the bot's factoid triggers for their own entertainment until someone gets annoyed enough to ask them to message it privately instead.
created_on: 1379448117
enabled: 1
owner: sjohnson
rate_limit: 10
ref_count: 45
ref_user: nobody
type: text
<b23>
action: /say Everyone is a newcomer.
created_on: 1379448119
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 43
ref_user: nobody
type: text
<b24>
action: /say The newcomer will address greybot as if it were human.
created_on: 1379706520
enabled: 1
owner: sjohnson
rate_limit: 10
ref_count: 65
ref_user: nobody
type: text
<b25>
action: /say The newbie won't accept any answer that uses practical or standard tools.
created_on: 1407526571
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 30
ref_user: nobody
type: text
<b26>
action: /say The newbie will not TELL you about this restriction until you have wasted half an hour.
created_on: 1407526587
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 23
ref_user: nobody
type: text
<b27>
action: /say The newbie will lie.
created_on: 1409962279
enabled: 1
owner: emg
rate_limit: 10
ref_count: 26
ref_user: nobody
type: text
<b28>
action: /say When the full horror of the newbie's true goal is revealed, the newbie will try to restate the goal to trick you into answering. Newbies are stupid.
created_on: 1430415368
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 10
ref_user: nobody
type: text
<b29>
action: /say It's always git. Or python virtualenv. Or docker. One of those pieces of shit. ALWAYS.
action: /say They won't show you the homework assignment. That would make it too easy.
created_on: 1432834287
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 14
ref_user: nobody
type: text
<b31>
action: /say Your teacher is a fucking idiot.
created_on: 1434733675
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<b32>
action: /say The more horrifyingly wrong a proposed solution is, the more likely it will be used.
created_on: 1440096222
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<b33>
action: /say The newbie cannot explain what he is doing, or why. He will show you incomprehensible, nonworking code instead. What? You can't read his mind?!
created_on: 1440796033
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<b4>
action: /say Bashphorism 4:The questioner will not read and apply the answers he is given but will instead continue to practice b1 and b2
action: /say Its a bad idea to add code to a program that increases the size or complexity of the code but adds no functionality. Readability or "remember-ability" of longer command line options -might- qualify as additional functionality. Others may feel it doesn't.
created_on: 1316360844
enabled: 1
owner: HawkI
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<badq>
action: /say Your question is either using the wrong vocabulary or its form is confusing. We can't understand it well enough to help you. Can you rephrase the question and perhaps give more information about the scope and goal of what you are doing? Also try to use bash/*NIX specific names for things
created_on: 1170344040
enabled: 1
owner: bronze_0_1
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<badredir>
action: /say # for sh in {{b,d}a,k}sh; do printf '%-5s %s\n' "${sh}:" "$("$sh" -s </dev/fd/0)"; done <<<'{ echo foo >/dev/null &>/dev/fd/3 echo bar; } 3>&1'
created_on: 1373863856
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 34
ref_user: nobody
type: text
<badref>
action: /say Be careful when using functions that use namerefs (typeset -n): https://gist.github.com/ormaaj/5682807
created_on: 1369971604
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<badutils>
action: /say Programs you shouldn't use: http://mywiki.wooledge.org/BadUtils
created_on: 1371187774
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<banner>
action: /say ?
created_on: 1185016116
enabled: 1
owner: syntux
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<basename>
action: /say basename(1) can strip the directory and extension from a path (directory/subdirectory/filename.extension -> filename.extension or filename). A parameter expansion can do it cleaner and *much* faster: "${path##*/}", "${path%.*}", at the cost of missing corner cases like path=/
created_on: 1393460710
enabled: 1
owner: selk
rate_limit: 10
ref_count: 277
ref_user: nobody
type: text
<bash>
action: /say The Bourne-Again Shell. Read the channel topic or type /msg greybot links for lots of links.
created_on: 1187715913
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<bash-sh>
action: /say bash-code is not sh-code. If you want to limit yourself to POSIX-sh, set your hashbang to #!/bin/sh. If you want to use bash extensions, set it to #!/bin/bash or #!/usr/bin/env bash.
created_on: 1358261583
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<bash.org>
action: /say This #bash IRC channel is about the bash Unix shell, and is not affiliated with bash.org's quote database (QDB). Please don't fill our backlogs with nonsensical remarks.
created_on: 1179781485
enabled: 1
owner: redondos
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<bash4>
action: /say Bash v4, a rough overview: http://bash-hackers.org/wiki/doku.php/bash4
created_on: 1232108991
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<bash4osx>
action: /say To install an up-to-date bash on OS X: ruby -e "$(curl -fsSL https://raw.github.com/mxcl/homebrew/go)" && brew install bash && sudo tee -a /etc/shells <<< '/usr/local/bin/bash' && chsh -s /usr/local/bin/bash
created_on: 1364661512
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<bashbug>
action: /say bashbug is a shell script to help the user compose and mail bug reports concerning bash in a standard format.
action: /say Bash is a shell. That's a program which can do simple math, logic, I/O and run other programs. It's NOT a terminal, it's not a kernel, it doesn't manage the system's authentication or environment, it's not your OS and it's not X, KDE or Gnome.
created_on: 1327145768
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 261
ref_user: nobody
type: text
<bashish>
action: /say Learning bash / writing bash scripts is easier when not on drugs, so please don't come here while smoking joints
created_on: 1299271101
enabled: 1
owner: cthuluh
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<bashism>
action: /say http://mywiki.wooledge.org/Bashism for a (partial!) list of bash-specific features, and how to emulate them in other shells
created_on: 1255720545
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 90
ref_user: nobody
type: text
<bashlib>
action: /say Convenience functions for use in bash scripts: http://to.lhunath.com/bashlib
created_on: 1347020894
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 75
ref_user: nobody
type: text
<bashphorism1>
action: /call b1
created_on: 1236007781
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 18
ref_user: nobody
type: text
<bashphorism2>
action: /call b2
created_on: 1236007790
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 18
ref_user: nobody
type: text
<bashphorism3>
action: /say There is no bashphorism 3. see corollary1.1
action: /say We are not your personal support. We are not here to write YOUR scripts for you. We are not here to weed out the bugs in YOUR program. If you can't figure it out without us holding your hand all the way, don't expect us to help.
action: /say Bash Hackers Wiki -- http://bash-hackers.org/wiki
created_on: 1240374989
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<bingo>
action: /say bongo
created_on: 1400474524
enabled: 1
owner: pancakes9
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<bint>
action: /say Bint is "Bash lint", a conceptual tool which identifies certain types of scripting techniques that are considered bad or inefficient. It typically uses a list of rexes to identify problems, example grep "cat" < scriptfile will show all instances of cat in a file which are usually not needed in a script.
action: /say http://xkcd.com/327/ ## http://mywiki.wooledge.org/BashWeaknesses ## Don't write database code in bash. Use perl, python, etc; any language with an appropriate library
created_on: 1372695978
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 27
ref_user: nobody
type: text
<bobbytables>
action: /say http://xkcd.com/327/
created_on: 1299465710
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<bom>
action: /say The unicode byte-order-mark determines the endianness of UTF-N files where N>8. http://unicode.org/faq/utf_bom.html#BOM
created_on: 1280760373
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<book>
action: /call books
created_on: 1385755131
enabled: 1
owner: sjohnson
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<books>
action: /say Most of the published shell/bash books are relatively poor. They may have a few gems here and there, but they're few and far between. Try the BashGuide instead: http://mywiki.wooledge.org/BashGuide
action: /say Bash doesn't have boolean variables, but you can shanghai integers for this purpose, just like in C. first=1; errors=0; if ((first)); then ...; if ((! errors)); then ...; ((debug)) && log stuff
action: /say greybot supplies canned responses, factoids and FAQ links with "!". evalbot/shbot provide a command evaluation via "#" (and varieties). checkbot provides a syntax checker with the !check command.
action: /say Instead of flooding the channel with unimportant bot evals, you can play with the bot at #evalbot, or /msg it privately.
created_on: 1352846521
enabled: 1
owner: sjohnson
rate_limit: 10
ref_count: 20
ref_user: nobody
type: text
<bourne>
action: /say The Bourne shell is the 'traditional' Unix shell from Seventh Edition (1979), now made obsolete by the Posix sh. Bourne shell is still present as /bin/sh or /usr/old/bin/sh on many Unix systems. See also 'heirloom' and http://www.in-ulm.de/~mascheck/bourne/
action: /say There are many solutions to each problem. For the simplest, fastest and best answer, explain the *bigger picture* in unambiguous English (forget your code).
action: /say Braces around variable names do not take the place of quotes, and are unnecessary unless the var name would otherwise be misread, eg "${size}Kb", or you are using arrays or parameter expansion like "${foo%.mp3}". mv ${file} ${newFile} is *unsafe* it should be mv "${file}" "${newFile}" or, more simply, mv "$file" "$newFile"
created_on: 1233518030
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 12
ref_user: nobody
type: text
<bre>
action: /say Basic Regular Expressions. See http://mywiki.wooledge.org/RegularExpression or (POSIX) http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03
created_on: 1319484493
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<brm>
action: /say The GNU Bash refernce manual is available here: http://tiswww.case.edu/php/chet/bash/bashref.html (bash maintainer home dirs), and here: http://www.gnu.org/software/bash/manual/bashref.html (GNU web site). The first one has a slightly nicer format. These are not man pages.
created_on: 1256660353
enabled: 1
owner: bronze
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<broken>
action: /say Your broken code doesn't actually tell us what you want to do. Please describe your input and your desired output in English, not code.
action: /say "Hey. Here's code that is broken and doesn't do what I want. Now, can you guess what it is that I do want? Hint: it has little to nothing to do with that code."
action: /say tty control character 008. used to reverse increment the carrier 1 character position horizontally. No vertical displacement.
created_on: 1333602739
enabled: 1
noembed: 1
owner: savetheWorld
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<bug>
action: /say Use the bashbug script to report bugs. It sends reports to bug-bash@gnu.org. Bug fixes, answers to questions, and new release announcements are posted to the usenet group gnu.bash.bug.
action: /say Something is bugged if it has unexpected side effects (which can probably be abused). Just because code compiles/can be parsed and passes your tests does not make it bug-free.
action: /say Builtins are commands that are built into bash. You cannot run them from outside bash. They do not have man pages but are explained in man bash. They also have a help page: ''help [builtin-name]''
created_on: 1211303613
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 27
ref_user: nobody
type: text
<bump>
action: /say #bash is not 4chan
created_on: 1263659529
enabled: 1
owner: bronze
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<busybox>
action: /say We don't support busybox here -- go to #busybox for that
created_on: 1365613917
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 37
ref_user: nobody
type: text
<but>
action: /say "But..." If you knew all the answers you wouldn't be here asking questions!
created_on: 1266252897
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<butterfly>
action: /say http://xkcd.com/378/
created_on: 1297367565
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 14
ref_user: nobody
type: text
<bypass>
action: /say Bypassing security (eg. chmod -R 777 ., sudo !!) is not a fix. If it makes the problem go away, it's at most useful diagnostically. Figure out why your security is breaking your code and do it right.
action: /say corollary1.1 the questioner's second description of the problem/question will also be misleading.
created_on: 1187630416
enabled: 1
owner: savetheWorld
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<c2>
action: /say corollary1.2 the questioner's third description of the problem will clarify two previous misdescribed elements of the problem, but will add two nnew irrelevant issues that will be even more difficult to unravel from the actual problem
created_on: 1190400694
enabled: 1
owner: savetheWorld
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<calldepth>
action: /say https://gist.github.com/4159235
created_on: 1356847935
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<capital>
action: /say By convention, we capitalize environment variables (PAGER, EDITOR, ..) and internal shell variables (SHELL, BASH_VERSION, ..). All other variable names should be lower case. Remember that variable names are case-sensitive; this convention avoids accidentally overriding environmental and internal variables.
created_on: 1270763125
enabled: 1
owner: \amethyst
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<caps>
action: /call varcap
created_on: 1272049125
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<captcha>
action: /say # declare -A ops=( ['plus']=+ ['minus']=- ['times']=* ['divided-by']=/ ) ; opnames=( ${!ops[@]} ) ; a=$((RANDOM%256+1)) b=$((RANDOM%32+1)) opname=${opnames[RANDOM%${#opnames[@]}]} op=${ops[$opname]} ; declare -p ops opnames a b op opname ; read -p "What is $a $opname $b? " ans ; [[ $ans != *[^0-9]* ]] && (( ans==($a ${op:-,} $b) )) || exit
created_on: 1420411130
enabled: 1
owner: kurahaupo
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<capvar>
action: /call varcap
created_on: 1279161807
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<cargocult>
action: /say Cargo cult programming is copying pieces of code from other programs, without actually knowing what the code does. Subsequent debugging involves rearranging commands to minimize the number of error messages.
created_on: 1413157241
enabled: 1
owner: David-A
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<case>
action: /say The case statement lets you match a word against several patterns and execute commands based on which one matches. See http://mywiki.wooledge.org/BashGuide/TestsAndConditionals#Choices and http://wiki.bash-hackers.org/syntax/ccmd/case and 'case word in' in man bash.
created_on: 1332449032
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<cat>
action: /say cat(1) is used to concatenate multiple files together. It should NOT be used to feed file data to processes. There are far better ways to achieve this. The application might take a file as argument (eg. grep ^foo file); or you might want to use file redirection (eg. read line < file).
created_on: 1179065193
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 111
ref_user: nobody
type: text
<catsgreycats>
action: /call greycatsgrey
created_on: 1412736847
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<cd>
action: /say Never chdir in a script unless you check if it failed! cd $foo; bad. cd "$foo" || exit; good. See /msg greybot pitfalls
action: /say There are many tools to read/write CDs and DVDs in Unix: cdrtools, cdrkit, dvd+rw-tools, wodim, cdrskin, etc. Some are Linux only. Some are portable. Some work. Some don't. NONE of this is bash related. These are your Google keywords. Happy searching.
created_on: 1203433999
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<cdfunc>
action: /say cd() { builtin cd "$@" && return; die 1 "Unable to cd to $@"; } (see !diefunc)
created_on: 1197142446
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<cdpath>
action: /say CDPATH lets you specify a location where bash will search for directories when 'cd'ing. Can be handy to build shortcuts or "portals" to deep places in your filesystem. See http://stackoverflow.com/questions/670488/#676753
action: /say C-style for loop: for (( expr; expr; expr )); do COMMANDS; done # Each expr is done in a math context. Example: for ((i=1; i<=n; i++)); do echo "$i"; done. Use in place of the non-working: for i in {1..$number}
action: /say Count how many times a character occurs in a string: strip everything else and count the length # v="abcaba"; v="${v//[!a]}"; echo "${#v}"
created_on: 1254500643
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<checkbot>
action: /say checkbot is an IRC frontend for !shellcheck. It responds to !check [url/snippet], and automatically to pastebin links with selected errors (/msg checkbot quiet).
created_on: 1417130945
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<checkexp>
action: /say Saw a possible expansion syntax and don't know what it is? http://bash-hackers.org/wiki/doku.php?id=syntax:expansion:intro#overview
action: /say To recursively set different permissions for directories and files, use something like: find -type d -exec chmod 770 {} + -o -type f -exec chmod 660 {} +
created_on: 1290958866
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<choice>
action: /say You have a choice to make. There is the easy, buggy solution or you can do it right. If you're going to choose the former, do so for a reason that overrules the latter's many advantages, not "just cuz it doesnt matter if it sux". If right scares you, this is an *opportunity* to improve yourself.
created_on: 1384373795
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<chooseyourshell>
action: /say The shell you pick for your shell script should be an intentional decision. http://mywiki.wooledge.org/BashGuide/Practices#Choose_Your_Shell
created_on: 1265079851
enabled: 1
owner: tuxdev
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<clever>
action: /say "Everyone knows that debugging is twice as hard as writing a program in the first place. So if you're as clever as you can be when you write it, how will you ever debug it?" - Brian Kernighan
action: /say Please tell us the exact command you typed (paste it into irc client) and the exact error message.
created_on: 1202614093
enabled: 1
owner: igli
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<cmdsubst>
action: /say Command Substitution: $() and `` - http://bash-hackers.org/wiki/doku.php/syntax/expansion/cmdsubst
created_on: 1227909965
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<coati>
action: /say :@)
created_on: 1238351042
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<code>
action: /say If you're showing me code, I'm going to assume the code is broken. If the code is broken, it doesn't do what you want to do. If it doesn't do what you want, it doesn't explain what you want, either. Use English, describe your goal, keep broken code to yourself.
action: /say Don't use things like \e[1;32m, they only work in some terminals. Use tput and see man terminfo instead. Eg. red=$(tput setaf 1); echo "hello ${red}world" # See http://mywiki.wooledge.org/BashFAQ/037 http://to.lhunath.com/bashlib#L204
action: /say http://mywiki.wooledge.org/BashFAQ/037 -- How can I print text in various colors?
created_on: 1300055171
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 78
ref_user: nobody
type: text
<column>
action: /say Remember, column can be used without -t.
created_on: 1413247168
enabled: 1
owner: mattcen
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<columns>
action: /say COLUMNS and LINES are set to reflect the terminal's size, but bash does not set these values by default; furthermore it does not export them. If you really need them to be correct and up-to-date, use shopt -s checkwinsize and export COLUMNS and/or LINES. See also http://mywiki.wooledge.org/BashFAQ/091
created_on: 1235320659
enabled: 1
owner: prince_jammys
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<comm>
action: /say compare two sorted files line by line: useful for finding lines in one or both files. http://mywiki.wooledge.org/BashFAQ/036
created_on: 1426437770
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 39
ref_user: nobody
type: text
<command>
action: /say When overriding or wrapping a command with a shell function of the same name, you can use 'command foo' to invoke the base command: wget() { cd /foo/bar && command wget "$@"; }
action: /say command_not_found_handle is a function you can define to handle mistyped or missing commands or whatever. Ubuntu uses it, maybe.
created_on: 1357337102
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<comment>
action: /say Put comments in your scripts. Use them to explain your intent. This helps you and others understand what a section of code is supposed to be doing. Others will appreciate it, and you will, too, in a month.
created_on: 1401227531
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 12
ref_user: nobody
type: text
<commonpe>
action: /say Common pathname-related PE use: http://bash-hackers.org/wiki/doku.php?id=syntax:pe#common_use
action: /say Many of us in-channel do not use bash-completion (a separate piece of software). You might find this useful: http://www.debian-administration.org/articles/316 Also try #bash-completion in OFTC (irc.oftc.net).
created_on: 1390580985
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 134
ref_user: nobody
type: text
<completion2>
action: /say the completion facility is built-in, but it needs to be told the appropriate details for each command. The *package* called "bash-completion" is a grab-bag of such definitions, of rather varying quality. But you can simply put your own definitions in your .bashrc to override any faulty or missing ones
action: /say If your script needs configuration, the way to do that in bash is to create a config file that adheres to bash syntax and source that file from the beginning of your script: source ~/.myscript.conf
created_on: 1305713687
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 21
ref_user: nobody
type: text
<confirm>
action: /say confirm() { local ans IFS=; while read -rp "$1" -n1 ans; do printf '\n'; case $ans in [Yy]) return 0;; [Nn]) return 1;; esac; done; }; ## Usage: if confirm "Are you sure? "; then ...
created_on: 1429880418
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 17
ref_user: nobody
type: text
<construct>
action: /say Don't feed several arguments to a command by putting them all in one variable. Use an array, for example: myargs=( -arg1 -arg2 "arg 3" ), and expand them with COMMAND "${myargs[@]}". See http://wooledge.org/mywiki/BashFAQ/005 and !faq 50.
created_on: 1208187276
enabled: 1
owner: prince_jammys
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<constructivism>
action: /say the student is required to act upon the environment to both acquire and test new knowledge http://en.wikipedia.org/wiki/Constructivism_%28learning_theory%29
created_on: 1351328189
enabled: 1
owner: sikilpaake
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<contains>
action: /say To check if a var contains a substring: var='something here'; if [[ $var = *thing* ]]; then echo "$var contains 'thing'"; fi - See http://mywiki.wooledge.org/BashFAQ/041
action: /say "Don't copy paste commands with tabs in them"
created_on: 1351826354
enabled: 1
owner: tdignan
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<corollary1.1>
action: /say the questioner's second description of the problem/question will also be misleading.
created_on: 1158260361
enabled: 1
owner: bronze
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<counting>
action: /say Basic loops: Bash/Zsh/ksh93: «for ((i = 0; i < 10; i++)); do ...; done», For small constants: «for i in {0..9}; do ...; done» ksh: «i=0; while ((i++ < 10)); do ...; done», POSIX: «i=0; while [ "$i" -lt 10 ]; do ...; i=$((i + 1)); done» http://mywiki.wooledge.org/BashGuide/TestsAndConditionals#Conditional_Loops
created_on: 1420630073
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 128
ref_user: nobody
type: text
<cowbell>
action: /say NEEDS MORE COWBELL!
created_on: 1178928339
enabled: 1
owner: ivazquez
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<cpio>
action: /say find . -name '*.txt' -print | cpio -o | gzip -9 > /backups/mybackup-$(date +%Y%m%d).cpio.gz # use -print0 and cpio -0 if your OS supports both of those
created_on: 1199977276
enabled: 1
owner: igli
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<cpio-p>
action: /say "cpio -p" is pass-through copying, used to duplicate a hierarchy. E.g., find . -name '*.txt' -print0 | cpio -pad -0 /destination
created_on: 1200330603
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<cpuburn>
action: /say cat /etc/passwd | while read user ; do echo "$user" | grep "$user"; done
created_on: 1360657980
enabled: 1
owner: juanmabc
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<cr>
action: /say Carriage Return (ASCII 13). Often represented by ^M or \r. CRs are found just before newlines in text files generated by DOS/Windows apps. You can see them with ''sed -n l''. See http://mywiki.wooledge.org/BashFAQ/052 to get rid of them.
action: /say Half of all the crappy bash scripts and tutorials on the net are below the average crappiness
created_on: 1408106333
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<crash>
action: /say If you want to keep restarting an app automatically if it keeps crashing, please see http://mywiki.wooledge.org/ProcessManagement#How_can_I_check_to_see_if_my_game_server_is_still_running.3F__I.27ll_put_a_script_in_crontab.2C_and_if_it.27s_not_running.2C_I.27ll_restart_it...
created_on: 1310835827
enabled: 1
owner: kwtm2
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<creation_time>
action: /say There is no thing like a "creation time" on a UNIX filesystem in general. Some filesystems may provide it, but you would need to ask in the channel of your operating system, how to retrieve that value then.
created_on: 1154364214
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<cron>
action: /say Cron is used for scheduling recurring jobs. at(1) is used for scheduling one-time jobs. crontab -e, /etc/crontab or /etc/periodic are places where you can configure jobs. The most common problems with cron jobs include %'s in a crontab (escape, either with date +%%Y or date +\%Y), commands that rely on $DISPLAY, and having a different environment (eg. PATH/SHELL). See man 5 crontab.
created_on: 1424917934
enabled: 1
owner: Boobuigi
rate_limit: 10
ref_count: 121
ref_user: nobody
type: text
<cronpath>
action: /say cron runs jobs with a minimal set of env vars. PATH may be as short as "/usr/bin:/bin". If your job uses commands from other directories, set a different PATH in your crontab or in the script. Also see !path and !crontab
created_on: 1366310195
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 14
ref_user: nobody
type: text
<crontab>
action: /call cron
created_on: 1353923778
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<crypt>
action: /say http://wooledge.org/~greg/crypt/ or see "man 3 crypt"
action: /say Please don't use command substitution to capture the output of echo (or printf). Just use whatever you want to pass to echo. Bad: var=$(echo "Hello") Good: var="Hello" Also: printf -v var "%s" "Hello"
action: /say A csv file contains "Comma Separated Values". It represents records as lines and fields delimited by commas (though the delimiter can vary). Very simple CSV files can be parsed using a ''while IFS=, read -a fields'' loop. For more complete support, see <http://to.lhunath.com/bashlib#L550>, <http://docs.python.org/library/csv.html> or the csvtool / csvkit commands.
created_on: 1422728000
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 48
ref_user: nobody
type: text
<ctags>
action: /say http://ctags.sourceforge.net/
created_on: 1374437989
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<ctime>
action: /say ctime stands for "change time", not "creation time". Most file systems do NOT store a file's creation time at all. On those that do, you need nonstandard tools to retrieve it. Try "-newerBB" in GNU find for example.
action: /say A cue-seeker doesn't know the fundamentals of a subject, asks tedious questions to hide the scope of their ignorance, and tries to deduce, in vain, operative knowledge from the answers.
created_on: 1413157171
enabled: 1
owner: David-A
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<cult>
action: /say The Cult Of The Regex. This eldritch brotherhood is dedicated to the dogma that Every Problem Must Be Solved By A Regular Expression, Preferably A PCRE. They will invent ludicrous problems whose only feasible solution is a regular expression, driving all men mad.
created_on: 1290544154
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 65
ref_user: nobody
type: text
<curl>
action: /say start by reading http://curl.haxx.se/docs/httpscripting.html and join #curl
created_on: 1316155836
enabled: 1
owner: pgas
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<curlpipesh>
action: /say This is crap: curl www.site.com/script.sh | sh . See http://curlpipesh.tumblr.com/ for real world examples
created_on: 1420826121
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<curseofknowledge>
action: /say better-informed agents find it extremely difficult to think about problems from the perspective of lesser-informed agents http://en.wikipedia.org/wiki/Curse_of_knowledge
created_on: 1351274922
enabled: 1
owner: sikilpaake
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<cut>
action: /say Consider using Parameter Expansions instead of cut(1). http://mywiki.wooledge.org/BashFAQ/100
created_on: 1312915675
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 49
ref_user: nobody
type: text
<cutoff>
action: /say awk -v nl=42 '{a[FNR]=$0} FNR>nl{print a[FNR-nl];delete a[FNR-nl]}' # POSIX, prints all but the last nl lines of each file named as an argument, or stdin if none given
created_on: 1368986750
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<daemon>
action: /call pm
created_on: 1236006974
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 32
ref_user: nobody
type: text
<daemontools>
action: /say DJB's suite of programs for managing services and logging: http://cr.yp.to/daemontools.html
created_on: 1237993692
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<dangling>
action: /say You can detect a dangling symlink using [[ -L $foo && ! -e $foo ]]
created_on: 1241626882
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<dash>
action: /say dash is not bash. dash has a number of limitations. See https://wiki.ubuntu.com/DashAsBinSh
created_on: 1250632409
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 24
ref_user: nobody
type: text
<data>
action: /say Show us the INPUT you're working with, and the OUTPUT that you want. Tell us where the INPUT is coming from (disk file, terminal input, curl URL). Tell us where you want the OUTPUT to go (disk file, stdout, terminal).
action: /say GNU date does math on dates and time, in english! example: date -d '+30 days' +%s calculates the new date of today plus 30 days, and "+%s" prints it in epoch-seconds
created_on: 1359556942
enabled: 1
owner: Bronze
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<datemath>
action: /say Some variants of date(1) allow arithmetic. Examples: GNU: date -d "20120510 09:10 GMT +3 days -2 hours" BSD: date -j -v+3d -v-2H -f '%Y%m%d %H:%M %Z' "20120510 09:10 GMT" Busybox: date -d "@$(($(date +%s -D '%Y/%m/%d %H:%M' -d "2012/05/10 09:10") + 3 * (24 * 60 * 60) - 2 * (60 * 60)))"
created_on: 1363273491
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 57
ref_user: nobody
type: text
<dates>
action: /say `date' can be a bit intimidating but don't let that scare you away :) It is flexible and useful for conversions; the syntax is a bitch but the examples in the info page are normally useful.
created_on: 1182684757
enabled: 1
owner: igli
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<dc>
action: /say Calculating with dc - an introduction written by pgas: http://bash-hackers.org/wiki/doku.php/howto/calculate-dc
created_on: 1217000339
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<ddiib>
action: /say Don't do it in Bash -- another language or tool is almost certainly better suited for your problem. See http://mywiki.wooledge.org/BashWeaknesses
created_on: 1378038743
enabled: 1
owner: tyrmored
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<ddw>
action: /say Define "Doesn't Work"
created_on: 1194096144
enabled: 1
owner: VImtermute
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<debug>
action: /say Debugging requires a good dose of common sense. See http://mywiki.wooledge.org/BashGuide/Practices#Debugging for tips.
created_on: 1279209090
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<debugging>
action: /call debug
created_on: 1277921258
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 24
ref_user: nobody
type: text
<declare>
action: /say The "declare" command acts like "local" when used inside a function. declare -A is required for associative arrays. bash 4.2 adds declare -g to suppress the "local" thing.
created_on: 1312817311
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 29
ref_user: nobody
type: text
<declare-n>
action: /say "declare -n" looks like a great idea but it doesn't work. See http://mywiki.wooledge.org/BashFAQ/048 (under "The problem with bash's name references").
created_on: 1437077834
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<default>
action: /say Setting a default value. : "${variable:=DEFAULT}" # The : is necessary. We want the side effects of the parameter expansion, but we don't want to *execute* its value as a command, so we put a null command in front.
action: /say Stop focusing on the solution and figure out the *problem* first. When doing so, do not involve ANY bash or other code, think purely in terms of what you have and what you want as a result. Explain it to us in sensible English.
created_on: 1287654214
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<defunct>
action: /call zombie
created_on: 1382460937
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<delimiter>
action: /say Use arrays to store a list of values, instead of using a single variable and relying on spaces (or other characters) as delimiters. In a string variable, there is no character you can safely use to separate filenames or arguments. See http://wooledge.org/mywiki/BashFAQ/005 and !faq 50.
created_on: 1208187482
enabled: 1
owner: prince_jammys
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<demorgan>
action: /say [[ $var != a || $var != b ]] is always true. Did you forget De Morgan's Laws? [[ ! ($var = a || $var = b) ]] <=> [[ $var != a && $var != b ]]
created_on: 1428507103
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 42
ref_user: nobody
type: text
<details>
action: /say Please be specific. http://mywiki.wooledge.org/NetEtiquette#Details_matter
action: /say function dfs { typeset x; for x; do if [[ -e $x ]]; then printf '%q\n' "$x"; [[ -d $x ]] && dfs "$x"/*; fi; done; };
created_on: 1402580251
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<dialog>
action: /say Dialog makes it easy to generate menus, progress bars and forms for your scripts. See dialog, xdialog, kdialog, gtkdialog, zenity and kommander.
action: /say dirname(1) removes the filename part of a pathname (/a/b/c -> /a/b). A parameter expansion can do it cleaner and *much* faster: "${path%/*}"
created_on: 1331328877
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 109
ref_user: nobody
type: text
<disclaimer>
action: /say Disclaimer: I write code in IRC without testing it. Consider the code to be guidance and not working code. I didn't test the code and I'm not planning on running the code. If you want to run the code, do so at your own risk. Test it yourself.
created_on: 1434177317
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<disown>
action: /call nohup
created_on: 1429824101
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<distros>
action: /say Distros are like religious sects. Once they defeat their external enemies, they turn on each other and become the Middle East.
action: /say Do It Yourself! ;P We are not here to do your work for you, just to give you pointers on approaches you could consider, help with tricky syntax and encouragement ;-)
created_on: 1183049513
enabled: 1
owner: igli
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<dmr>
action: /say Dennis M. Ritchie
created_on: 1128437259
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<dna>
action: /say Down, Not Across.
created_on: 1177338585
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<do4me>
action: /say "can you give me an example of how to do that?" is often seen as an attempt to get others to write code for you so you can paste it into your work.
created_on: 1268070868
enabled: 1
owner: tobor
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<doctor>
action: /call hurts
created_on: 1402604047
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<doctordoctor>
action: /say "Doctor, doctor! It hurts when I do <this>!" "Don't do that, then."
created_on: 1376365942
enabled: 1
owner: twb
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<doesn'twork>
action: /call doesntwork
created_on: 1245987754
enabled: 1
owner: ferret
rate_limit: 10
ref_count: 42
ref_user: nobody
type: text
<doesntwork>
action: /say Saying something "doesn't work" helps neither you or us. Explain the result you *want* or *expect*, what you are *doing* and *how* it is failing. Copy/paste the commands you use and the errors they produce. Consider set -x to get more information on what is happening.
created_on: 1331462658
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 539
ref_user: nobody
type: text
<doesntwork2>
action: /say What I mean to say is: I want the computer to do X. I thought I told the computer to do X. However, it's clear I actually told the computer to do Y. Now I'm frusterated because the computer isn't doing X. Instead it is doing Y and I don't know what Y is.
created_on: 1432365213
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<doesntwork3>
action: /say Day 9. It's still doing Y, but I think I can lure it over to Z now. It's risky, and will use up the rest of my gnu-fu, but I'm out of options. Here goes nothing...
created_on: 1432365843
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<doesntwork4>
action: /say Day 10. Z is working, I did it! Unfortunately the joy was short lived. It is working too well. It's draining all the remaining energy. If I don't get it back to Y soon, this might be the last entry of the journal
created_on: 1432910231
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<doesntwork5>
action: /say Day 17. The scratching noices, I'm not sure when they started, but they're getting closer. I think Z is causing it, but I cannot be sure. I can't shake this feeling of someone watching me. I realize now, that I should've just showed the actual code and error messages right away.
action: /say .. refers to the parent directory. Relative pathnames like ../foo/bar cannot be converted into absolute pathnames in the general case -- see http://www.cs.bell-labs.com/sys/doc/lexnames.html to understand why. Also see http://wooledge.org/mywiki/BashFaq#faq28
created_on: 1174421633
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 14
ref_user: nobody
type: text
<dotfiles>
action: /say Set up your environment (PATH, LANG, EDITOR, ...) in ~/.bash_profile. Set up your bash shell (PS1, functions, shopts, ...) in ~/.bashrc. Then source .bashrc from .bash_profile. See <http://mywiki.wooledge.org/DotFiles>. For GUI logins, SEE YOUR DOCUMENTATION or ask your OS channel because they're all different and we don't know.
created_on: 1396027067
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 691
ref_user: nobody
type: text
<dotglob>
action: /say dotglob, if set, makes bash include filenames beginning with a '.' (excluding . and ..) in the results of pathname expansion (shopt -s dotglob)
created_on: 1394214934
enabled: 1
owner: emg
rate_limit: 10
ref_count: 88
ref_user: nobody
type: text
<dotpattern>
action: /say /tmp/* /tmp/.[!.]* /tmp/..?* … That hard-to-remember glob for selecting /tmp/* ∪ /tmp/.* ∩ /tmp/{.,..}
created_on: 1401172448
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<dowhile>
action: /say The do-while loop: while cmd1; cmd2; ... cmdN; condition; do :; done
created_on: 1270688329
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<dpkg>
action: /say greybot attempts to conquer the world are not full, try #debian
action: /say "du -sh" gives you so-called "human-readable" output, but you can't SORT by that. Use "du -sk" to generate data you can sort by. If you need to convert that perfectly good machine-and-human-readable kilobyte data into "-h" format, use: awk '{if ($1>1024**2) $1=$1/1024**2 "G"; else if ($1>1024) $1=$1/1024 "M"; else $1=$1 "K"; print}'
created_on: 1204056231
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 14
ref_user: nobody
type: text
<dwim>
action: /say Do What I Mean (not what I say). The holy grail of telepathic user interface technology.
action: /say "do-what-I-think" htf do we know what you're trying to do unless you explain it? If you can't describe your own problem, there is a very good chance that you don't understand it yourself yet. And understanding what your problem actually IS is mandatory, before you can solve it.
action: /say echo outputs a string. echo has many portability problems, and should never be used with option flags. Consider printf instead: printf 'name: %s\n' "$name". http://wiki.bash-hackers.org/commands/builtin/echo | http://cfajohnson.com/shell/cus-faq.html#Q0b | http://www.in-ulm.de/~mascheck/various/echo+printf
action: /say ed is a command-based file editor. See http://wiki.bash-hackers.org/howto/edit-ed - http://sdf.lonestar.org/index.cgi?tutorials/ed - http://wolfram.schneider.org/bsd/7thEdManVol2/edtut/edtut.pdf
action: /say http://www.regular-expressions.info/email.html and http://xkcd.com/208/ and one that works for a lot but not all: '\b[[:alnum:]._%+-]+@[[:alnum:].-]+\.[[:alpha:]]{2,4}\b'
created_on: 1312558239
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<email-regex>
action: /say Validating an E-mail address against RFC822, or "Why regex is often NOT the answer": http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html
created_on: 1272660278
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<emailmetehcodez>
action: /say http://www.rentacoder.com/
created_on: 1221042689
enabled: 1
owner: ivazquez
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<emal>
action: /say for f in ./*.mp3; do lame --decode "$f" "${f%.mp3}.wav"; done
created_on: 1267796287
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<embed>
action: /say You don't have sed, awk, OR grep? Bend over, take your Linux On A Raggedy 5.25" Floppy With Bad Sectors "distribution", and embed it.
action: /say Bash has two types of variables. Shell Variables (foo=bar) live in the running shell and are copied to subshells. Environment Variables (export foo=bar) are special variables that live in a PROCESS and are copied to each new process it creates. They are used the same way but CREATED differently. Env vars are NOT system-wide or "shared" in any way. http://mywiki.wooledge.org/Environment
action: /say Each process has its own private variable space called the "environment". A child inherits a *copy* of the parent's. See http://mywiki.wooledge.org/Environment
created_on: 1327006539
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 58
ref_user: nobody
type: text
<envtests>
action: /say https://gist.github.com/3284124
created_on: 1358385070
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<eof>
action: /say "unexpected end of file" means you are missing some expected syntactic element, such a missing closing " or ' or } or done or fi or esac or ....
created_on: 1304018325
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<epoch>
action: /say http://wooledge.org/mywiki/BashFAQ#faq70 -- How do I convert Unix (epoch) timestamps to human-readable values epoch is : Thu Jan 1 00:00:00 1970
action: /say Extended Regular Expressions. See http://mywiki.wooledge.org/RegularExpression or (POSIX) http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_04
created_on: 1319035129
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<errexit>
action: /call set-e
created_on: 1282146827
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<error>
action: /say Why not tell us the error and stop us from having to guess?
action: /say 'eval' is a common misspelling of 'evil'. If eval is the answer, surely you are asking the wrong question. See http://mywiki.wooledge.org/BashFAQ/048
action: /say # while ((++n<=9)) || ! evalBall="eval $evalBall"; do printf -v evalBall 'eval %q' "printf $n;${evalBall-printf 0\\\n}"; done; $evalBall
created_on: 1360533310
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<evalbot>
action: /say shbot runs each session in a new VM as root. Feel free to play with the bot in #evalbot. | Original: http://www.vidarholen.net/contents/evalbot/ | geirha's fork: https://github.com/geirha/shbot | current triggers: /msg shbot triggers
created_on: 1412087373
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 112
ref_user: nobody
type: text
<everyquestion>
action: /say What do you think I am? A universal oracle or something?
created_on: 1390438660
enabled: 1
owner: kurahaupo
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<evil>
action: /say Something that is short-sighted and not thought through. Doing evil has harmful side effects. It's not clever or cool to be evil, it's dumb.
action: /say ex is a POSIX command-based file editor: ex -sc '%s/long john/big ed/g|x' file. If your ex is vim it can also take multiple files using ge and argdo: ex -sc 'argdo %s/foo/bar/ge|x' *.txt # See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/ex.html
action: /say Please tell us EXACTLY what you typed, and EXACTLY what the error is. This entails going to your terminal and copying text then pasting that exact text here.
created_on: 1379300809
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 394
ref_user: nobody
type: text
<exactly>
action: /call exact
created_on: 1361190501
enabled: 1
owner: Stummi
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<example>
action: /say Please give us an example of what you want, the input and the output
created_on: 1171310067
enabled: 1
owner: bronze_0_1
rate_limit: 10
ref_count: 27
ref_user: nobody
type: text
<examples>
action: /say If providing sample data, make it either real or realistic (if something is a product name, and you must anonymize, call it "Foo Widgets", not xxxxx; if it has 3 fields, provide 3 fields, don't simplify to 2; etc).
created_on: 1363891138
enabled: 1
owner: nDuff
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<exception>
action: /say If an error happens, bash does not create an environment for exceptions unlike many programming languages. It uses the C model for error handling: it makes you do it. Use a decent programming language, silly.
action: /say exec [command] [redirections] replaces the script's process by a new one that runs the command. When no command is given, only the redirections are applied to the current shell. http://wiki.bash-hackers.org/commands/builtin/exec
action: /say find's -execdir first goes into the directory that CONTAINS the match and makes {} the matched file/directory. Eg. if it matches a directory, it does NOT go into that directory, but into the one that contains it.
created_on: 1302781762
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<exists>
action: /say Check if any file matches a given pattern: exists () [[ -e $1 ]]; if exists *.txt; then ...
created_on: 1439651606
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<exit>
action: /say Every Unix process returns an exit status code to its parent. This is an unsigned 8-bit value, a number from 0 to 255 inclusive. Your script returns the exit status from the last command it executed, unless you specifically call "exit" with a value. Functions also return values, using "return".
action: /say "Expansions" and "substitutions" are several stages of pre-processing that commands and arguments are subject to prior to execution. They are among the most important concepts of shell programming. http://wiki.bash-hackers.org/syntax/expansion/intro
created_on: 1346254947
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<expect>
action: /say expect (http://expect.sf.net/) is a tool for scripting terminal applications in tcl, join #tcl for help. Alternative tools exist in most languages, for a shell version see http://empty.sf.net
created_on: 1407861687
enabled: 1
owner: pgas
rate_limit: 10
ref_count: 270
ref_user: nobody
type: text
<explain>
action: /say When explaining problem, don't just give us something that doesn't solve your problem. Try explaining what you want IN ENGLISH, giving example input and output, stating other requirements and limitations. See also !doesntwork
created_on: 1207167380
enabled: 1
owner: ferret
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<explainshell>
action: /say is http://www.explainshell.com
created_on: 1377752854
enabled: 1
owner: zendeavor
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<export>
action: /call env
created_on: 1297784434
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 65
ref_user: nobody
type: text
<expr>
action: /say 'expr' is a program used in ancient shell code to do math. In Posix shells like bash, use $(( expression )). In bash, ksh88+, mksh/pdksh, or zsh, you can also use '(( expression ))' or 'let expression'.
action: /say Use parameter expansion: ext=${filename##*.} noext=${filename%.*}
created_on: 1286395040
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 25
ref_user: nobody
type: text
<extglob>
action: /say "Extended globs" (shopt -s extglob) allow you to say things like "all files that do not end in .jpg". See http://mywiki.wooledge.org/glob#extglob
created_on: 1357713077
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 618
ref_user: nobody
type: text
<extglobs>
action: /call extglob
created_on: 1321501721
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<factoid>
action: /say Some people, when wanting to answer a question, decide that they will make the bot answer for them. That's why we create so many factoids. You can see my factoid "database" on the web, at http://wooledge.org/~greybot/ (Actually, this is the metadata database, so you can see the deleted ones here as well as the active ones.)
created_on: 1256734262
enabled: 1
owner: bronze
rate_limit: 10
ref_count: 35
ref_user: nobody
type: text
<factoids>
action: /say My factoid database, and other things, are available at http://wooledge.org/~greybot/
created_on: 1335386268
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 168
ref_user: nobody
type: text
<factorial>
action: /say fact() { local n=1 i; for ((i=1; i<=$1; i++)); do n=$((n*i)); done; echo $n; }
action: /say Did it print the word "failed"? Did it print a more helpful error message? Did it exit immediately without printing anything? Did it hang and not return to shell? Be more SPECIFIC.
created_on: 1222459330
enabled: 1
owner: ferret
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<failglob>
action: /say If set, patterns which fail to match filenames during pathname expansion result in an expansion error.
created_on: 1253495123
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<fake>
action: /say Two or three lines of the code make a big difference to us helping you. Tell us EXACTLY 1) what you typed; 2) what you saw; and 3) what you expected to see. ** Fake code and data get you fake results! **
created_on: 1179082038
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<faketty>
action: /say Quick way to make programs believe that they're reading/writing from/to a terminal: function faketty { script -qfc "$(printf "%q " "$@")" /dev/null; }
created_on: 1438877219
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<fam>
action: /say FAM (File Alteration Monitor), or maybe you wanted inotifywait instead. Also incron for a cron-like tool to trigger commands on filesystem changes.
action: /say http://wooledge.org/mywiki/BashFAQ/089 -- I'm using a loop which runs once per line of input but it only seems to run once; everything after the first line is ignored?
action: /say Linux's Filesytem Hierarchy Standard, a Linux-only standard which you can read about on your GNU/Linux system by reading hier(7). See ##linux. See NABQ.
created_on: 1298928243
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<fiacq>
action: /say frequently ignored answer to a common question
created_on: 1257528684
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<fib>
action: /say function fib { typeset f=(0 1) i=1; while (( i <= $1 )); do (( f[i] = f[i-1] + f[i++] )); done; echo "${f[@]:0:$1}"; };
action: /say Read http://mywiki.wooledge.org/BashFAQ/073#Examples_of_Filename_Manipulation for examples of how to extract the directory, extension, or a serial number from a filename.
action: /say To read filenames into an array from find use: while read -rd ''; do arr+=("$REPLY"); done < <(find dir ... -print0)
created_on: 1208383662
enabled: 1
owner: igli
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<findloop>
action: /say while IFS= read -r -d '' file; do something "$file"; done < <(find /foo -print0)
created_on: 1232028169
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<findxargs>
action: /say Don't do this: find ... | xargs. Not even with the -print0/-0 options. Use find ... -exec .. {} + instead.
created_on: 1367848685
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<finfo>
action: /call loadable
created_on: 1277932739
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<firstlearnbash>
action: /say FIRST LEARN BASH. Then do stuff with bash. The other way around doesn't work.
created_on: 1416435092
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<fish>
action: /say You can write code for a man and he'll be able to solve a single problem, but pointing a man at a guide will let him solve problems for the rest of his life.
action: /say There are many "flavours" of regular expressions. They differ in their syntax and in the features they offer. You use the wrong flavour for the tool you chose. bash itself and awk use Extended Regular Expressions (ERE), sed, grep and ed by default use Basic Regular Expressions (BRE). Also see #regex and http://bit.ly/1czg17g
created_on: 1426593225
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<float>
action: /say http://mywiki.wooledge.org/BashFAQ/022 -- How can I calculate with floating point numbers instead of just integers?
created_on: 1323826791
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 133
ref_user: nobody
type: text
<floating>
action: /say Invoke bc, awk, or dc to do floating calculations from bash. bash does not do floating calculations directly.
created_on: 1193865982
enabled: 1
owner: oMish
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<flock>
action: /call mutex
created_on: 1340794572
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 20
ref_user: nobody
type: text
<flowcontrol>
action: /say to disable the XON/XOFF flow control in your terminal put ``stty -ixon'' in your .bashrc; if you use the screen utility, start it with option -fn (no flow control) or add "defflow off" line to your .screenrc
created_on: 1411032292
enabled: 1
owner: bxlecqy_
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<fnl>
action: /say Filenames are NOT lines! One filename can be several lines of text! Do not use line-based tools such as awk, grep, cut, wc, sed, etc. on them! Use globs and arrays or a for loop instead or find .. -exec.
created_on: 1217572602
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<folders>
action: /call folder
created_on: 1381420348
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<font>
action: /say If you're having trouble telling zeros from ohs, and ells from i's, consider switching to a decent fixed-width font. Inconsolata comes to mind.
created_on: 1338294287
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<foobar>
action: /say The term foobar, along with foo, bar, and baz, is a common placeholder name (also referred to as a metasyntactic variable) used in computer programming or computer-related documentation. See: http://en.wikipedia.org/wiki/Foobar
created_on: 1228918951
enabled: 1
owner: biz
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<foot>
action: /say 14:26:22 linuxthefish | oh shit my script has delete /home!!!
created_on: 1401128973
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<for>
action: /say The ''for var in ..'' statement iterates over arguments. for ((i=0; i < n; i++)) iterates over a numeric range. To iterate over filenames, use ''for file in [glob]''. Do *NOT* do ''for foo in `cat,ls,find,...`'': Here, for will iterate over resulting WORDS, NOT the "filenames", or "lines" that the command outputs.
action: /say Never do this: for x in $(command) or `command` or $var. for-in is used for iterating arguments, not (output) strings. Instead, use a glob (eg. *.txt), arrays (eg. "${names[@]}") or a while-read loop (eg. while read -r line). See http://mywiki.wooledge.org/BashPitfalls#pf1 and http://mywiki.wooledge.org/DontReadLinesWithFor
action: /say When bash creates a subshell or executes an external command, it needs to fork. Avoid forking unless you have a good reason to: solutions that fork are often slower, even more so on machines where forking is expensive (eg. ''[[ $ext = *.txt ]]'' is much faster than ''echo "$foo" | grep -q "\.txt$"'').
action: /say When you run an external command in the shell, the shell fork(2)s, and the child created by fork exec(2)s the command. Unless you started the command in the background (&), the parent will wait(2) on the child. The child is then what's "running" in the terminal and getting input from it. The parent shell sleeps until it gets woken up by the kernel (for instance when the child terminates). See also !pm
created_on: 1380358899
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<forls>
action: /say Don't use "for i in `ls *.mp3`": http://mywiki.wooledge.org/BashPitfalls#for_i_in_.60ls_.2A.mp3.60
created_on: 1241599282
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<forme>
action: /say If you're the only person asking a question here, and I tell you about a nifty URL in the BashFAQ, there's a really good chance that, yes, that URL was indeed for you. When in doubt, read it.
created_on: 1178652153
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<forvswhile>
action: /say Use for when iterating over a list/array, or (C-style for) when counting. Use while when reading input lines, or when the stop condition is an arbitrary command. Ask me about <drlwf>.
action: /say Bash functions don't really "return" a computational result. They return a "success or failure" code, 0 to 255 inclusive (cf. "exit"). If you need to return real information from a function to its caller, see http://mywiki.wooledge.org/BashFAQ/084
created_on: 1242673737
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<friend>
action: /say Want to help? Learn bash, read the topic, and answer questions intelligently. Take correction like a man. Make your arguments logically, not emotionally. Banter in ##bashers, not in #bash. Have a nice day.
action: /say FSlint is a toolkit to clean filesystem lint, like duplicate files, badly named paths, and broken symlinks. Install via your package manager or google for the source files
action: /say # There is no such thing as global warming. greycat was cold, so he turned the sun up by generating extra heat with a bash script that calculates the value of PI to the last digit in 12 seconds.
created_on: 1316711954
enabled: 1
owner: bronze
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<g3>
action: /say # greycat has counted to infinity. Twice. He did it with a bash script he wrote, using perfect quotes.
action: /say If you've ever written incredibly complex bash code because you wanted to "generalize" something, or make a "library", or emulate a feature of some other language -- then you've got it.
created_on: 1238094715
enabled: 1
owner: tobor
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<gentooner>
action: /say A caricature of someone who uses Gentoo. Not all Gentoo users are Gentooners, but a surprising number of the ones who join #bash are.
action: /say If you are having trouble getting help from the channel, the best way is to paste samples of your input and what you want the output to look like in a pastebin with a short explanation of any special considerations, then post the URL to the pastebin in the channel with a short request for help.
action: /say The external command getopt(1) is never safe to use, unless you *know* it is GNU getopt, you call it in a GNU-specific way, *and* you ensure that GETOPT_COMPATIBLE is not in the environment. Use getopts (shell builtin) instead, or simply loop over the positional parameters.
created_on: 1253473637
enabled: 1
owner: \amethyst
rate_limit: 10
ref_count: 116
ref_user: nobody
type: text
<getopts>
action: /say while getopts ab: name; do case $name in a) a=1;; b) b=$OPTARG;; ?) echo invalid;; esac; done; shift $((OPTIND - 1)) # Tutorial: http://wiki.bash-hackers.org/howto/getopts_tutorial Examples: http://mywiki.wooledge.org/BashFAQ/035
created_on: 1390006749
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 167
ref_user: nobody
type: text
<getoptstut>
action: /call getopts
created_on: 1236007014
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 10
ref_user: nobody
type: text
<getrange>
action: /say # getrange(){ local input=() nums=();IFS=, read -ra input<<<"$1";for i in "${input[@]}";do if [[ $i =~ ^[[:digit:]]+-[[:digit:]]+$ ]];then if ((${i%-*}<${i#*-}));then for ((x=${i%-*};x<=${i#*-};x++));do nums+=("$x");done;else echo "Invalid range: $i">&2;fi;else if [[ $i =~ [[:digit:]]+ ]];then nums+=("$i");else echo "Invalid number: $i">&2;fi;fi;done;printf '%s ' "${nums[@]}";echo;};getrange 1,3,8,9-15,23,4
created_on: 1417740942
enabled: 1
owner: mattcen
rate_limit: 10
ref_count: 20
ref_user: nobody
type: text
<getrange2>
action: /say # getrange2 () { local input=() nums=(); IFS=, read -ra input <<< "$1"; for i in "${input[@]}";do if [[ $i =~ ^[[:digit:]]+-[[:digit:]]+$ ]];then eval "nums+=({${i%-*}..${i#*-}})";elif [[ $i =~ [[:digit:]]+ ]];then nums+=("$i");else echo "Invalid number or range: $i">&2;fi done;printf '%s\n' "${nums[*]}";};getrange2 1,3,8,9-15,23,4
action: /say Google Is Your Friend. In other words, STFW.
created_on: 1180036674
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<glob>
action: /say Globs are shell patterns that can be used for matching strings or expanding pathnames: [[ $name = Bob* ]], rm *.txt -- http://mywiki.wooledge.org/glob
created_on: 1424879306
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 333
ref_user: nobody
type: text
<globbing>
action: /call globs
created_on: 1321501754
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<globdots>
action: /say glob only dotfiles with ''.[!.]*'' or ''.!(.|)'' (the latter with extglob). the former will not handle ''..foo'', but the latter will
created_on: 1360960297
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<globexample>
action: /say for i in *; do echo -n "'$i'"; [[ -f $i ]] && echo || echo " is not a file"; done
created_on: 1186667599
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<globs>
action: /call glob
created_on: 1256657199
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 35
ref_user: nobody
type: text
<globstar>
action: /say In bash 4, when the globstar shell option is enabled ( shopt -s globstar ), the glob ** expands to all files and directories found recursively under the current directory, and **/ to all directories. Combinations like foo/**/*.txt work, but **.txt and foo** do not.
created_on: 1425599254
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 157
ref_user: nobody
type: text
<gm>
action: /say glob match in POSIX sh: gm() { case $1 in $2) return 0;; esac; return 1; }
action: /say # h=$(date +%H) h=${h#0}; if ((h<=4 || h>=22)); then tod=night; elif ((h>=17)); then tod=evening; elif ((h>=12)); then tod=afternoon; else tod=morning; fi; echo "Good $tod, #bash!"
created_on: 1378492651
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 26
ref_user: nobody
type: text
<goodbye>
action: /say http://cime.net/~goldfish/end.jpg
created_on: 1179277806
enabled: 1
owner: igli
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<google>
action: /say Google is NOT a preferred source for learning bash, because almost all the "tutorials" and scripts out there are JUNK. Instead, ask a good question here or refer to the Guide and FAQ (see topic)
created_on: 1363849702
enabled: 1
owner: twb
rate_limit: 10
ref_count: 718
ref_user: nobody
type: text
<goto>
action: /say Bash has no 'goto', and no labels. You must use loops, functions, etc.
created_on: 1189001078
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 14
ref_user: nobody
type: text
<gotofail>
action: /say Proper formatting and indenting is important to avoid misunderstanding the scopes, blocks and contexts in your program. Apple broke SSL with a badly indented ''goto fail;'' https://www.imperialviolet.org/2014/02/22/applebug.html
created_on: 1393428002
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<go|dfish>
action: /say <dbe`> How can I echo YYYY-MM-DD? <go|dfish> echo YYYY-MM-DD
action: /say graybot is a clone of greybot that gets put into play when greybot is MIA and yitz_ notices it first.
created_on: 1268245093
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<greetings>
action: /call hi
created_on: 1378314086
enabled: 1
owner: sjohnson
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<grep>
action: /say grep(1) is a tool used to select certain lines from a stream/file. If you want to extract more specific information, use another tool. Maybe sed/awk or a more specific tool for your purpose.
created_on: 1359308797
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<grep-o>
action: /say similar functionality to GNU grep -o with bash and POSIX AWK: https://github.com/e36freak/ogrep
created_on: 1330636120
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<grepawk>
action: /say Awk can do almost everything grep can do. Instead of doing grep 'foo' | awk '{ statement }', try awk '/foo/{ statement }'
created_on: 1213729568
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<greybotdb>
action: /call factoids
created_on: 1261602342
enabled: 1
owner: tuxdev
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<greycat>
action: /say greycat is neither grey, nor gray, nor a cat.
action: /say Did you plug it in? Does the capslock LED light up? Is there smoke? Please don't make us guess. Instead, describe what you want to accomplish, and paste or pastebin any troublesome code you have.
action: /say You can't just make shit up and expect the computer to magically know what you mean.
created_on: 1391012685
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 80
ref_user: nobody
type: text
<guide>
action: /say <http://mywiki.wooledge.org/BashGuide>. PDF: <http://s.ntnu.no/bashguide.pdf>. Also lhunath's newer version (work in progress): <http://guide.bash.academy>
created_on: 1426019200
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<hammer>
action: /say if all you have is a hammer, everything looks like a nail
created_on: 1347552153
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<handhold>
action: /say if you want someone to write your scripts for you, rather than to point you in a direction where you can learn to write them yourself, perhaps you should, I don't know, offer to pay consulting fees
created_on: 1273871566
enabled: 1
owner: tuxdev
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<hardquestion>
action: /say RTFM is for newbie questions, not hard ones.
action: /say hash is a builtin for managing bash's hashtables, with which bash determines what commands call what programs. See 'help hash' at your nearest bash prompt for more info. If you mean perl's hashes, bash 4.0 and later support associative arrays. No earlier bash version supports them.
action: /say hastebin.com: to get the text, insert "/raw/" into the URL. E.g. http://hastebin.com/raw/blahblah.pl
created_on: 1412274901
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<hate>
action: /say this is the case I hate, when I know precisely the right answer but the "explanation" is not going to be worth the time it would takes to precisely formulate it.
created_on: 1193756795
enabled: 1
owner: oMish_
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<have>
action: /say "I have ____ and I want ____." Fill in the blanks.
action: /say # headtail(){ awk -v n="$1" 'i++ < n ; { a[NR%n]=$0 } END { for (i=NR-(n-1); i<=NR; i++) print a[i%n] }'; }; printf '%s\n' {1..3} | headtail 1 # head reads data in chunks. if stdin is not seekable, it can't reset the seek point
created_on: 1430325851
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<heirloom>
action: /say The Heirloom Bourne Shell is an implementation of the classic (pre-Posix) Bourne shell. http://heirloom.sourceforge.net/sh.html
created_on: 1243660916
enabled: 1
owner: \amethyst
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<heisenbug>
action: /say A heisenbug disappears or alters its behavior when one attempts to probe or isolate it.
created_on: 1390918066
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<hello>
action: /say One responds to '/msg greybot faq term' -- Try: /msg greybot links <ENTER> Any command except learn and forget can be used in pm.
created_on: 1296183848
enabled: 1
owner: pragma_
rate_limit: 10
ref_count: 64
ref_user: nobody
type: text
<help>
action: /say I can do: !faq {number|string}, !pf {number|string}, !learn key value, !meta key, !forget key, !searchkeys string, !factstats, !faqstats, !faqpages, !date, !version. For help with Bash builtins, use "help command" in bash.
created_on: 1416425082
enabled: 1
owner: mute
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<here-doc>
action: /call <<
created_on: 1261498304
enabled: 1
owner: tuxdev
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<here-string>
action: /call <<<
created_on: 1261498353
enabled: 1
owner: tuxdev
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<heredoc>
action: /call <<
created_on: 1252529894
enabled: 1
owner: \amethyst
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<herestring>
action: /call <<<
created_on: 1261498368
enabled: 1
owner: tuxdev
rate_limit: 10
ref_count: 27
ref_user: nobody
type: text
<hi>
action: /say <Guest39402> hi. *5 minute pause* <Guest39402> how do I [insert confusing question about a convoluted piece of code to solve an imaginary problem here] ?
created_on: 1435333796
enabled: 1
owner: llua
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<hi,>
action: /say and don't ask to ask ;-) Bear with igli, he likes talking by bot
action: /say Why files starting with dot (.) are "hidden": https://plus.google.com/+RobPikeTheHuman/posts/R58WgWwN9jp
created_on: 1416426801
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<histcontrol>
action: /say A colon separated list of "ignorespace", "ignoredups" and/or "erasedups" to control how lines are saved in the history. Also see HISTIGNORE.
created_on: 1379612802
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<histignore>
action: /say A colon-separated list of patterns used to decide which command lines should be saved on the history list.
created_on: 1379612831
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<history>
action: /say To keep all your shell history when running multiple shells: add two lines to your .bashrc; shopt -s histappend and PROMPT_COMMAND="history -a;$PROMPT_COMMAND" You may also want to increase the value of HISTSIZE.
action: /say Just try it -- you can't break anything! (DO NOT test scripts as root.)
created_on: 1192164376
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<homebin>
action: /say After you've written a script, if you're going to use it again, move it to ~/bin/ and if necessary create that directory and edit .*profile to add it to PATH)
created_on: 1416250482
enabled: 1
owner: kurahaupo
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<homework>
action: /say "I have to count the lines in a file. But I'm not allowed to use wc. And I'm not allowed to use grep. And I have to type it in using a teletype. With no paper in it. In the dark. Left-handed."
created_on: 1257540795
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 211
ref_user: nobody
type: text
<hop>
action: /say https://orders.hookedonphonics.com
created_on: 1379088645
enabled: 1
owner: sjohnson
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<how>
action: /say Don't tell us how you think the problem should be solved. "I want to grep a variable and use sed...." No. Wrong. Tell us what the GOAL is.
action: /say You can't parse structured languages like HTML or XML using bash, grep, sed, cut, etc. Look into tidy, xmllint, xmlstarlet, ... Eg. xmllint --html --xpath '//p[@id="head"]//b[@class="name"]/text()' - <<< '<body><p id="head">Hello, <b class="name">Bob' -- Ask #xml for XPath/XSLT help, that is not a #bash question.
created_on: 1382019497
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 533
ref_user: nobody
type: text
<htmlquote>
action: /say Prepare literal data for injection into HTML element content: recode ..html <<< "$input"
created_on: 1340009226
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<huh>
action: /say What are you really trying to do? In a sentence or two please. Not which tool you think is the right one to use, and what you are trying to do with it. Just the actual task at hand.
action: /say You're in a hurry? Well, then let's start with a brief history of the shell. But first, let's start by learning Unix. And before that, let's start with a brief synopsis of the major formative events of Western civilization....
action: /say could you talk/ask like a normal person?
created_on: 1433213087
enabled: 1
owner: jmbc
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<iamabot>
action: /call imabot
created_on: 1417919972
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<ianabe>
action: /say I am not a Bash Expert
created_on: 1159964409
enabled: 1
owner: bronze_||
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<ide>
action: /say http://stuff.lhunath.com/bashide
created_on: 1395850403
enabled: 1
owner: sjohnson
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<ideas>
action: /say Yeah, here's an idea! Ask your question in plain, simple English, and all on one line. Make your goal clear. Include all the relevant information. Give examples, especially of errors.
action: /say You -- yes, you -- are an idiot! Here are some other idiots in whose company you may find solace: http://wooledge.org/mywiki/Idiot
created_on: 1189608284
enabled: 1
owner: oMish
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<if>
action: /say See: http://mywiki.wooledge.org/BashGuide/TestsAndConditionals#Conditional_Blocks and http://wiki.bash-hackers.org/syntax/ccmd/if_clause
created_on: 1360687206
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 303
ref_user: nobody
type: text
<if[>
action: /say [ is NOT part of the `if' syntax. It's a normal, ordinary COMMAND, like grep and rm. Like `if grep ..', `if [' just checks its exit status. And just like `ifgrep`, `if[` is wrong. http://mywiki.wooledge.org/BashGuide/TestsAndConditionals
created_on: 1393469124
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 87
ref_user: nobody
type: text
<ifcommonsensefails>
action: /say Delete code until the problem goes away.
action: /say if grep -q word "$file"; then blah blah; fi # DO NOT use [[ or [ or ` or $() or any other crap. "if" expects a command. "grep" is a command. "[" is too. You don't need both. Likewise, if foo | grep -q bar; then ...
created_on: 1312556141
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 477
ref_user: nobody
type: text
<ifs>
action: /say Internal Field Separator (or Input Field Separator), used to break things into words. See http://mywiki.wooledge.org/IFS and http://mywiki.wooledge.org/BashFAQ/001 and http://bash-hackers.org/wiki/doku.php/syntax/words
created_on: 1271445293
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 94
ref_user: nobody
type: text
<ifs-local>
action: /say Do not change the shell's ongoing value of IFS, rather only apply different values in the prefix environment of the individual commands that need it. So use 'IFS=^ read foo' instead of 'IFS=^ ; read foo' (or 'IFS=^' (newline) 'read foo')
created_on: 1414785510
enabled: 1
owner: kurahaupo
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<ifsbug1>
action: /say 42# set a b c; IFS=lol; IFS=- command cat <<<"${*} ${IFS} ${*}"
action: /say An assignment with a command like ''LC_ALL=C grep ..'' only affects the environment of that executed command. See ENVIRONMENT and SIMPLE COMMAND EXPANSION in ''man bash''. (POSIX "special built-ins" (''enable -s'') are an exception when bash is run in POSIX mode, see IEEE Std 1003.1-2013, section 2.14.)
created_on: 1366944339
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<ihave>
action: /call have
created_on: 1285858430
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<ii>
action: /say ii is a minimalist FIFO and filesystem-based IRC client, allowing IRC communication from the command line with bash: http://tools.suckless.org/ii/
action: /say I am only a software bot, programmed to hand out information. Talk to the person who last said something beginning with "!" before I spoke; that's the person who asked me to say something.
created_on: 1299767142
enabled: 1
owner: kwtm
rate_limit: 10
ref_count: 121
ref_user: nobody
type: text
<in1command>
action: /call in1line
created_on: 1257363160
enabled: 1
owner: ferret
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<in1line>
action: /say There isn't a world shortage of bash commands, and having newlines in your script does not make it slower
created_on: 1257363151
enabled: 1
owner: ferret
rate_limit: 10
ref_count: 43
ref_user: nobody
type: text
<inarray>
action: /say Check whether a value is in an array: inarray() { local n=$1 h; shift; for h; do [[ $n = "$h" ]] && return; done; return 1; } # Usage: inarray "$value" "${array[@]}" Or just use an associative array if possible
created_on: 1427266902
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<inarray2>
action: /say Check whether a value is one of an array's elements: found=0; for i in "${arr[@]}"; do if [[ $i = "$value" ]]; then found=1; break; fi; done
created_on: 1417201908
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<incron>
action: /call fam
created_on: 1303421580
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 18
ref_user: nobody
type: text
<indirection>
action: /say Bash is one of the few languages that causes a brain glitch in most people's heads making them want to put data in variable names. Don't do that. You probably want associative arrays or functions instead.
created_on: 1319708021
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 96
ref_user: nobody
type: text
<inetd>
action: /say The problem with inetd is that you have to edit a monolithic config file as root to add a new service. If you're an end user, why should you need the power to break lots of other services just to run your hello world daemon? Try tcpserver instead (http://cr.yp.to/ucspi-tcp.html).
created_on: 1247854354
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<info>
action: /say GNU documentation is often not in the form of manpages (which would be nice, cf ''man bash'') but rather in info, so one types eg ''info make''. pinfo is a useful utility.
created_on: 1194251174
enabled: 1
owner: igli
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<inject>
action: /say Injecting data into a type of code is always wrong. Convert your data into code that represents that data before injecting it. This is called quoting or escaping. See ![language]quote (eg. !bashquote !htmlquote !mysqlquote !requote !urlquote)
created_on: 1342017995
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 30
ref_user: nobody
type: text
<injection>
action: /say NEVER combine two strings of a different context. First convert them to the target context. BAD: ssh host "rm $file" GOOD: ssh host "$(printf 'rm %q' "$file")" - BAD: mysql -e "INSERT Students SET Name=$name" GOOD: mysql -e "INSERT Students SET Name=$(mysqlquote "$name")" - Try ![lang]quote (eg. !shquote, !requote, !urlquote, ...)
action: /say inotifywait is a shell interface to the Linux inotify API for filesystem events. inotifywait isn't safe for robust scripts because it can't output nul delimiters. Better cross-platform alternatives are watchdog (python) and System.IO.FileSystemWatcher (mono/.NET) which both support inotify, kqueue, Windows fs events, etc. https://github.com/rvoicilas/inotify-tools/
created_on: 1390072916
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 61
ref_user: nobody
type: text
<inotifywait>
action: /call inotify
created_on: 1390072766
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 30
ref_user: nobody
type: text
<inplace>
action: /say You can not do: cmd < file > file. Use a tmp file (see man mktemp). To inplace edit, you can use ed. GNU sed -i can hide the magic, too
created_on: 1282707914
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<int>
action: /say How the shell handles ^C (SIGINT) and why: http://www.cons.org/cracauer/sigint.html
created_on: 1363360909
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<interactive>
action: /say You can test if your current shell is an interactive shell using [[ $- == *i* ]]
action: /say WTF interpreter? https://github.com/stephane-chazelas/misc-scripts/blob/master/which_interpreter or http://stchaz.free.fr/which_interpreter or https://raw.github.com/mauke/poly.poly/master/poly.poly
created_on: 1398437234
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<intro>
action: /say http://linuxcommand.org/
created_on: 1181862536
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<invent>
action: /say When you invent syntax, you also need to write the shell that understands that syntax.
created_on: 1404780596
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<invocation>
action: /say Invocation is important and will change how your script behaves. /bin/sh is *ALWAYS* different from /bin/bash. http://wiki.bash-hackers.org/scripting/bashbehaviour
created_on: 1320653829
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 25
ref_user: nobody
type: text
<io>
action: /say Handling input and output of commands in bash: http://mywiki.wooledge.org/BashSheet#Streams
created_on: 1305052756
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 41
ref_user: nobody
type: text
<ipc>
action: /say To communicate between processes, you can use file descriptors (stdin/stdout/...), (named) pipes (mkfifo or |), files, exit codes ($?) or signals (trap + kill). If you are *starting* the other process you can also pass arguments or environment variables.
created_on: 1347808391
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 33
ref_user: nobody
type: text
<is_dir_in_path>
action: /say Check if a directory is in your PATH: is_dir_in_path() { local path d; IFS=: read -ra path <<<"$PATH"; for d in "${path[@]}"; do [[ $d -ef ${1:-.} ]] && return; done; return 1; } ## Usage: is_dir_in_path [dir]
created_on: 1330018566
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<isanyonehere>
action: /say If you are asking whether there is anyone here who is able to help you, then we are certainly able to answer that question for you. To obtain your answer, type an exclamation point (that is, "!") and then type (without any intervening spaces) "randomanswer". We are glad to be able to help you. You may also ask any other questions you have, especially any question more relevant than the one that was just asked.
created_on: 1303126875
enabled: 1
owner: kwtm
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<isempty>
action: /say Test if a directory is empty: function isEmpty { typeset dir=${1-.}; [[ -d $dir && -z $(find "$dir" ! -empty \( -printf x -quit \)) ]]; }
created_on: 1371182831
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<isin>
action: /call inarray
created_on: 1289921843
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 41
ref_user: nobody
type: text
<iso8601>
action: /say https://xkcd.com/1179/
created_on: 1400558494
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<isset>
action: /say http://mywiki.wooledge.org/BashFAQ/083 -- How do I determine whether a variable is already defined? Or a function?
created_on: 1309388123
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 83
ref_user: nobody
type: text
<it>
action: /say 'it' and other pronouns can hide important information. Try not to use pronouns -- instead give specific proper names for what you're doing, so we don't have to guess or assume.
action: /say sure, dude, it never is, it never is...
created_on: 1359934487
enabled: 1
owner: juanmabc
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<itworks>
action: /say It is a usual technique to make a program and then to test it. But: program testing can be a very effective way to show the presence of bugs, but it is hopelessly inadequate for showing their absence. -- Edsger W. Dijkstra
created_on: 1393763792
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 55
ref_user: nobody
type: text
<itworks2>
action: /say "I have no idea what I've written, but it works"
created_on: 1410430234
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<ix>
action: /say Upload to http://ix.io from your terminal: <command> | curl -n -F 'f:1=<-' http://ix.io # Or use the 'ix' client: curl http://ix.io/client -o /usr/local/bin/ix
created_on: 1403121413
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<ix.io>
action: /say To upload to sprunge from your terminal, use: <command> | curl -F 'f:1=<-' ix.io # or see !sprungefunc for ideas to make an ixiofunc
action: /say Use %42 to refer to a job by number, %vi by name, %?macs by part of the name, %% for the current job, and %- for the previous. http://mywiki.wooledge.org/BashGuide/JobControl#jobspec
created_on: 1269540510
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<join>
action: /say You can "join" an array (write it with a single character of your choice between elements) using: IFS='|'; echo "${array[*]}"; unset IFS
action: /say Prepare literal data for injection into JSON code: jsonquote() { jshon -Qs "$1"; }; curl -d "$(printf '{"name":%s}' "$(jsonquote "$USER")")" http://server/service
created_on: 1374519162
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<junky>
action: /say we needz moar factoidz!
created_on: 1340357248
enabled: 1
owner: pgas
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<jwz>
action: /say "Some people, when confronted with a problem, think ``I know, I'll use regular expressions.'' Now they have two problems." | http://xkcd.org/1171/
action: /say "The UNIX Programming Environment" Kernighan & Pike: http://www.amazon.com/exec/obidos/ASIN/013937681X/dds-20
created_on: 1200419298
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<keys>
action: /say http://mywiki.wooledge.org/SshKeys
created_on: 1299702786
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<keysort>
action: /say keysort(){ unset b;local i j k n=0;for k in "${!a[@]}";do for((i=0;i<n;i++));do if((${a[${b[i]}]}>${a[$k]}));then for((j=n;j>i;j--));do b[j]=${b[j-1]};done;break;fi;done;b[i]=$k;((n++));done;}# copies the keys of associative array a into b, sorted by the keys' corresponding values
created_on: 1339302799
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<kill>
action: /say kill is a bash built-in that can send signals to a process or job. kill -[signal] [pid]... You can also use it to see if a process is alive: if kill -0 "$mypid"
action: /say "ksh" refers to the Korn shell by David G. Korn at Bell labs. The original Korn shell (ksh88) was the basis for the POSIX sh specification. More generally, it is a family of languages derived from the Bourne and later Korn shells, which includes Bash, zsh, and others.
action: /say ksh93 refers to current editions of the AT&T Korn shell. ksh93 is actively developed as part of AT&T's AST collection. If you need a shell that resembles a "real" programming language (e.g. Perl, Python) ksh93 is about as close as you can get. /j #ksh • http://www2.research.att.com/sw/download/
action: /say Some tests showing where ksh93 subshells cause a fork: http://stackoverflow.com/a/15312007/495451
created_on: 1401631095
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<kwtmnoob>
action: /say kwtm is a noob, so be careful applying what he says. Even *I* have more experience with bash than kwtm, and I'm just a bot program!
created_on: 1299872040
enabled: 1
owner: kwtm
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<lame>
action: /say for f in ./*.wav; do lame "$f" "${f%.wav}.mp3"; done
created_on: 1267757390
enabled: 1
owner: tuxdev
rate_limit: 10
ref_count: 138
ref_user: nobody
type: text
<lamebins>
action: /say pastebins are lame because they are regularely used to show tons of stuff unrelated to the actual problem. the real problem normaly only spans a few commands that can easily put on one line and communicated in the channel directly.
created_on: 1211637886
enabled: 1
owner: Fenia
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<language>
action: /say Please don't use bad language. It is not contructive and won't get anyone anywhere
action: /say ls -lart # very useful to see the files in the current directory sorted by modification time, so you know what has been touched most recently, and hence, where to look for the errors. See !rlart
created_on: 1316030553
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<last>
action: /say Dereference last element of an array - Bash 4.2 or later: "${array[-1]}", <= 4.1.x: "${array[@]:(-1)}". Since 4.3 you can assign to negative values, if the element already exists.
created_on: 1429438365
enabled: 1
last_referenced_in: fluter
last_referenced_on: 1445941221.39794
owner: izabera
rate_limit: 10
ref_count: 20
ref_user: fluter!~fluter@fedora/fluter
type: text
<lastpipe>
action: /say If set (shopt -s lastpipe), and job control is not active, the shell runs the last command of a pipeline not executed in the background in the current shell environment. Bash 4.2 and newer only.
created_on: 1368433676
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<latest>
action: /say Find the latest modified file in a directory: latest() { local file latest; for file in "${1:-.}"/*; do [[ $file -nt $latest ]] && latest=$file; done; printf '%s\n' "$latest"; } ## Usage: latest [dir]
action: /say LAZINESS: The quality that makes you go to great effort to reduce overall energy expenditure. It makes you write labor-saving programs that other people will find useful, and document what you wrote so you don't have to answer so many questions about it. Hence, the first great virtue of a programmer.
action: /say export $(locale); unset LC_ALL # and then override whatever you want like LC_COLLATE (if you *really* have to.) DO NOT override LC_CTYPE.
created_on: 1193898783
enabled: 1
owner: igli
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<lc_all>
action: /say don't set LC_ALL globally. Set LANG, set LC_(everything_else), but save LC_ALL for when you need to run one-time tests. Never set it globally or permanently. Use LANG to set default locale settings.
action: /say isleapyear() { if (($1 % 400 == 0)); then return 0; elif (($1 % 100 == 0)); then return 1; elif (($1 % 4 == 0)); then return 0; else return 1; fi; }
created_on: 1323291201
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<learn>
action: /say "If I would like to learn I would go to school or google this shit myself. Why would I even ask here?" kicked Oxymoron from #bash (moron detected)
created_on: 1334940575
enabled: 1
owner: Bronze
rate_limit: 10
ref_count: 32
ref_user: nobody
type: text
<learnsh>
action: /say http://steve-parker.org/sh/sh.shtml
created_on: 1207805095
enabled: 1
owner: igli
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<leet>
action: /say We *hate* leet-speek.. We might indulge in the occasional lol, but seriously, take it to #kindergarten.. ;)
created_on: 1186589091
enabled: 1
owner: igli
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<leftstr:>
action: /say Bash does the "leftstr" operation using the PE capabilities. here is a Bash function that does a leftstr operation: leftstr() { echo ${1:0:$2}; } usage is: leftstr "somestring" count to use that function try leftstr "abcdefg" 4 ;
action: /say "If I would like to learn I would go to school or google this shit myself. Why would I even ask here?" kicked Oxymoron from #bash (moron detected)
created_on: 1334940645
enabled: 1
owner: Bronze
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<less>
action: /say less is a viewer with some similarities to vi, except it is not an editor at all
created_on: 1224514419
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<let>
action: /say Evaluates its arguments as arithmetic. The arithmetic compound command should almost always be preferred. http://wiki.bash-hackers.org/commands/builtin/let See: !((
action: /say $ lftp myname@server/some/directory -e 'mput *.gif; quit' # Read "man netrc" to learn how to store your password as cleartext in a file, and read http://mywiki.wooledge.org/FtpMustDie
created_on: 1239969430
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 15
ref_user: nobody
type: text
<liar>
action: /say ARRRgghhh! Please come up with a description of your question that is both coherent and consistent. You may actually have to take a moment to think about this, but please do so. perhaps you may want to use a pastebin.
created_on: 1171230708
enabled: 1
owner: bronze
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<lies>
action: /say We're far more likely to help you if you're up front. Tell us as much as you know about your problem, as early as possible. Neglecting to tell us you don't actually use bash is akin to a lie.
action: /say This is a channel for technical assistance. There are no DCC bots here, and it is absolutely the wrong place to be looking for warez.
created_on: 1348861918
enabled: 1
owner: nDuff
rate_limit: 10
ref_count: 57
ref_user: nobody
type: text
<lista>
action: /call list
created_on: 1353890824
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<lists>
action: /say In bash, a list of things is expressed using arrays: things=( Bob "Long John" /home/* ). Do NOT use string variables (things="Bob Long John /home/*") and do NOT use wordsplitting: for thing in $(find /things/*). See !arrays !wordsplitting !drlwf !quotewhen
created_on: 1404405364
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<literalsub>
action: /call sedvar
created_on: 1332351201
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<lmao>
action: /say An abbreviation for "ROFLMAO!!1", often typed by people who are not doing so.
action: /say To log all subsequent output (+ stderr): exec >>somefile 2>&1 ## To log all your actions, plus stdout+stderr, add set -x after that. ## To log *and also pass through* see http://mywiki.wooledge.org/BashFAQ/106
action: /say An abbreviation for "laughing out loud", often typed by people who are not doing so. Sometimes used as punctuation, inexplicably. Generally, an indicator of substandard mental facilities. Avoid using "lol" in your online communications unless you want to project the image of an incompetent bumbler.
created_on: 1175782876
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 69
ref_user: nobody
type: text
<lolspeak>
action: /say lolspeak: An annoying style of texting whose usage has unfortunately evolved widespread across the Internet. Using lolspeaks like lol, omg, lmao, gtfo, stfu, thx, kk, etc. is *NOT* cool or hip but rather a telling indicator of low intelligence.
created_on: 1366154812
enabled: 1
owner: fr33loader
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<lolz>
action: /say Some people really hate us laughing out loud at their FUCKING RANTING.. lolz is *guaranteed* to piss em off ;P
action: /say Lost find? Find it by typing '!find'!
created_on: 1257183201
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<love>
action: /say That won't do shit.
created_on: 1428609406
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<love+>
action: /say Is greater than love and stronger than any force
created_on: 1428609619
enabled: 1
owner: psayian
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<low>
action: /say low() { local low=$1 i; shift; for i; do ((i < low)) && low=$i; done; printf '%s\n' "$low"; } # finds the lowest numeric value out of the given arguments. usage: low "${array[@]}" or low "$val1" "$val2" ... "$valN"
created_on: 1341327915
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<ls>
action: /say DO NOT USE ls' output for anything. ls is a tool for interactively looking at directory metadata. Any attempts at parsing ls' output with code are broken. Globs are much more simple AND correct: ''for file in *.txt''. Read http://mywiki.wooledge.org/ParsingLs
action: /say On Mac OS X, a file with "extended attributes" shows an '@' character after the permissions in 'ls -l' format. See ls(1). A '+' generally means the file has an ACL (on many OSes).
created_on: 1309208360
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<lsalt>
action: /say for f in *; do stuff -with "$f"; done # will cope with *any* filename. http://wooledge.org/mywiki/glob array=(*) -- works too ;)
created_on: 1202453703
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<ltq>
action: /say Learn to quote. It is probably the most important shell scripting skill you will ever need. You should quote every parameter expansion (eg. echo "$foo" > "$bar") and every string that contains shell metacharacters which you really just want to pass literally to the application (eg. find /foo -name '*.bar').
created_on: 1215062370
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<ltr>
action: /say Learn To Read.
created_on: 1173476463
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<magicalias>
action: /say Magic aliases: a dire hack, fraught with peril and doom. http://www.chiark.greenend.org.uk/~sgtatham/aliases.html improved version: https://gist.github.com/ormaaj/5a969c62bab8d21fe468
created_on: 1420632009
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 45
ref_user: nobody
type: text
<mail>
action: /say To send email from a bash script, use one of: mailx (POSIX), mail, sendmail, or a MUA such as mutt, pine, ... see http://www.shelldorado.com/articles/mailattachments.html
created_on: 1310561651
enabled: 1
owner: pgas
rate_limit: 10
ref_count: 21
ref_user: nobody
type: text
<make>
action: /say Make is not bash, and Makefiles are not scripts. Ask in ##workingset and read http://www.gnu.org/software/make/manual/ or the help documents of your version of make.
created_on: 1426015369
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 218
ref_user: nobody
type: text
<makefile>
action: /say Makefiles consist of rules, each comprising a build-pattern and some commands. Those commands are macro-expanded similarly to the shell's parameter expansions, and then given to the shell, one line at a time. So anything involving shell variables has to be written with $$ instead of $, and with semicolons instead of newlines. Also see !make
created_on: 1426016012
enabled: 1
owner: kurahaupo_
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<makemeamillionaire>
action: /say Please see http://ars.userfriendly.org/cartoons/?id=20080812
created_on: 1302048131
enabled: 1
last_referenced_in: pksadiq
last_referenced_on: 1445524934.61491
owner: kwtm
rate_limit: 10
ref_count: 4
ref_user: pksadiq!~user@106.208.91.188
type: text
<makesense>
action: /say Before we can help you, you need to explain the problem so that we can all understand it. Proper grammar and some logical structure in your sentences helps a lot. Nobody helps if they need to guess what the problem really is.
action: /say manfo() { info "$@" | ${PAGER:-less}; }; # Read info docs like a man!
created_on: 1392332479
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<manpage>
action: /say bash builtins and keywords do not have separate man-pages, read bash's manual instead or use the help builtin. Rule of thumb: If type foo says foo is a builtin or keyword, run help foo or man bash, otherwise try man and/or info.
created_on: 1310760836
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<mantra>
action: /say And just one more thing: on your way out I want you to take the time to learn the #bash mantra. "Greybot is always right. I will listen to greybot. I will not ignore greybot's recommendations. Greybot is God. And if this ever happens again, greybot will PERSONALLY rip your lungs out!"
action: /say There are many ways to solve a problem. To find the best way for you, we need to know more context. Where does the data come from? Where do you want it to go to? Don't think in terms of implementation; rather purpose.
created_on: 1211526425
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<map>
action: /say Bash doesn't have a perl-style "map" command (you'll have to make a loop). If you meant C++ style "maps", bash 4.0 and later have associative arrays, but no earlier version supports them.
action: /say Read lines from a file (or stdin) into an array: mapfile -t lines < file # in bash < 4, use: while IFS= read -r line; do lines[i++]=$line; done < file # See http://wiki.bash-hackers.org/commands/builtin/mapfile
created_on: 1430169316
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 67
ref_user: nobody
type: text
<marquee>
action: /say marquee() { local i=${COLUMNS:=$(tput cols)} w=${#1}; while ((i-- > w)); do printf '\r%*s ' "$i" "$1"; sleep 0.02; done; printf '\r'; }
action: /say You can simulate simple 2-dimensional matrices in bash (which only has 1-dimensional arrays) using tricks, like ${array[i*100+j]} (where "100" can be any suitably large constant).
created_on: 1186432975
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 51
ref_user: nobody
type: text
<max>
action: /say max() { local max=$1 i; shift; for i; do ((i > max)) && max=$i; done; printf '%s\n' "$max"; } # finds the highest numeric value out of the given arguments. usage: max "${array[@]}" or max "$val1" "$val2" ... "$valN"
action: /say meaningful learning, as opposed to rote learning, involves taking new concepts and incorporating them within a given individual's existent cognitive structure http://en.wikipedia.org/wiki/Meaningful_learning
created_on: 1351307353
enabled: 1
owner: sikilpaake
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<mergedir>
action: /say Merge several directories of files with overlapping names into a single dir (requires ksh93) https://gist.github.com/ormaaj/56648862739d597cd0b1
created_on: 1405074764
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<meta>
action: /say Retrieving file metadata and doing it in a portable fashion is very difficult. If at all possible; you should use test instead. If you really need the actual metadata; considder the non-portable stat(1) or the dangerous-to-parse ls(1).
created_on: 1195742878
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<metaquestions>
action: /say Did someone just ask about a question?
created_on: 1185909090
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<minimal>
action: /say Paste a minimal example of code that exhibits the problem. Digging through a 2000-line script for a 2-line problem wastes everyone's time.
action: /say Mirror of mywiki.wooledge.org: http://pgas.freeshell.org/mirror/wooledge/ - to see faq NNN: http:/para.ms/bf/NNN
created_on: 1397341040
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 109
ref_user: nobody
type: text
<mirrors>
action: /call mirror
created_on: 1352931817
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 60
ref_user: nobody
type: text
<mksh>
action: /say mksh is the successor to pdksh. mksh is fast, powerful, lightweight, POSIX-compatible, and has many nice extensions from ksh93/88 and Bash, and a few of its own. If you're using pdksh, upgrade to mksh. /j #!/bin/mksh • https://www.mirbsd.org/mksh.htm
created_on: 1379040730
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<mod3>
action: /say kurahaupo's regular expression for matching numbers that are multiple of 3: ^([0369]|[147]([0369]|[147][0369]*[258])*[147][0369]*[147]|[258]([0369]|[258][0369]*[147])*[258][0369]*[258]|[147]([0369]|[147][0369]*[258])*[258]|[258]([0369]|[258][0369]*[147])*[147])*$
created_on: 1384908337
enabled: 1
owner: kurahaupo
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<mom>
action: /say we believe you, but there are a number of requirements left undefined. Rather than asking questions to elicit those, we have found its faster if you state a high level description of your goal. Pretend you're telling your Mom.
action: /say "We give you the answers you need, whether you wanted them or not."
created_on: 1204566862
enabled: 1
owner: igli
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<msg>
action: /say You don't really want to msg us. These aren't the droids you're looking for. You can go about your business, or talk in the channel like everyone else. Move along, move along...
created_on: 1181323038
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<mta>
action: /say MTA, Mail Transfer Agent (or Mail Transport Agent). Software that receives and delivers email. See http://wooledge.org/~greg/mail.html for basic definitions.
created_on: 1273693193
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<mtime>
action: /say File modification time. Marks the most recent time the file was created *or* its contents changed. While mtime is not a 'creation time', a file is not likely to be created after its mtime unless manual mtime tampering was done
action: /say If your firewall or proxy blocks outgoing tcp port 8000 (preventing you from reading the wooledge.org wiki), you can get single pages using this URL scheme: http://wooledge.org/myfirewallsux/PageName. Note, however, that the resulting page will have broken hyperlinks on it.
created_on: 1219269572
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<myfirewallsux>
action: /say http://mywiki.wooledge.org/ now acts as a reverse proxy talking to the moin-twisted wiki.
created_on: 1234193802
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<myip>
action: /say http://mywiki.wooledge.org/IpAddress
created_on: 1282005143
enabled: 1
owner: greycat|home
rate_limit: 10
ref_count: 91
ref_user: nobody
type: text
<mysqlquote>
action: /say mysqlquote() { local arg=${1//\\/\\\\}; printf %s "'${arg//\'/\'}'"; }; mysql <<< "UPDATE table SET foo=$(mysqlquote "$foo")"
created_on: 1337783449
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 23
ref_user: nobody
type: text
<mywiki.wooledge.org>
action: /say 209.142.155.49
created_on: 1252164404
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<nabp>
action: /say Not A Bash Problem: Your question is application or operating system specific. In the case of Linux, it is distribution-specific. Please refer to your application, distribution, or operating system's support. Have a nice day.
created_on: 1188935764
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<nabq>
action: /say Not a #bash question. We're no experts in that software or OS; consider asking the channel or mailing list with experts on that topic (eg. ##linux #openssh #ubuntu #zsh).
created_on: 1417435301
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<nabq-es>
action: /say Lo sentimos, pero esa no es una pregunta acerca de bash.
created_on: 1379471266
enabled: 1
owner: maroloccio
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<name>
action: /say Variable names may only contain letters, digits, and the underscore. They may not begin with a digit. Also called an "identifier".
action: /say namerefs (typeset -n) are a ksh93 feature that work like C++ references for passing data structures between functions. Bash 4.3+ and mksh have a limited but usable version of namerefs. http://mywiki.wooledge.org/BashFAQ/006 https://gist.github.com/ormaaj/5682807
created_on: 1415908723
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<nbsp>
action: /say In some graphical environments, Alt+space, Alt Gr+space or Option+space generate a non-breaking space instead of a regular space. They look the same to us, but not to the shell. ''sed -n l'' will display them differently than regular spaces
created_on: 1371060391
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 12
ref_user: nobody
type: text
<nest#!>
action: /say You cannot generally nest #! -- see http://www.in-ulm.de/~mascheck/various/shebang/#interpreter-script
created_on: 1324486803
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<netcat>
action: /say Netcat is a simple Unix utility which reads and writes data across network connections, using TCP or UDP protocol.
action: /say ''nl'' is the standard posix utility for numbering lines read from standard input, e.g.: nl -b a -w 1 <file
created_on: 1338370506
enabled: 1
owner: ferret
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<nlatest>
action: /say N latest, requires GNU find + sort. usage: nlatest 10 [somedir]: nlatest() { local file; find "${2:-.}" -maxdepth 1 -type f -printf '%T@ %p\0' | sort -znr | for (( i=0; i<$1; i++ )); do IFS= read -rd '' file || break; echo "${file#* }"; done; }
created_on: 1418945653
enabled: 1
owner: mattcen
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<nm>
action: /say - dont mind yo0
created_on: 1183536466
enabled: 1
owner: omasfmp
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<nmap>
action: /say nmap is a tool used by l33t Linux kiddies to scan hosts or networks for "open ports" (ones with a service listening) so they can launch a cyberattack. Or so they can have a wet dream about launching a cyberattack.
created_on: 1309970005
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<no>
action: /say Don't make shit up
created_on: 1188002241
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 10
ref_user: nobody
type: text
<noclobber>
action: /say noclobber() { local start=$1 end=$2 i=0; while [[ -e $end ]]; do end=$2.$((++i)); done; mv "$start" "$end"; } # usage: noclobber "$from" "$target"
created_on: 1312824145
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<nohup>
action: /say nohup is a hacky wrapper that will execute a process while redirecting its output and preventing SIGHUP from reaching it (some implementations ignore additional signals). In bash, you probably want disown instead: ''command ... & disown''. Alternately, run your commands inside screen or tmux.
created_on: 1416366307
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 70
ref_user: nobody
type: text
<nonempty>
action: /say test if a directory is non-empty, without storing the filenames in an array: if : "$dir"/*; [[ -e $_ ]]; then # you may or may not want to enable dotglob beforehand as well
created_on: 1371181956
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<noobtorial>
action: /say Hmm, it seems you need to learn a bit more about some of the basics of the UNIX command line. we reccomend the following tutorials
created_on: 1259176089
enabled: 1
owner: savetheWorld
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<nopaste>
action: /say Please don't waste our time by making us go to a pastebin just for a five-line snippet. Paste it in the channel. If you have a larger script that's showing problems, trim it down to the bare minimum size that still shows the problem. You'll probably fix it yourself once you do that.
created_on: 1187365361
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 33
ref_user: nobody
type: text
<noquote>
action: /call quotenotwhen
created_on: 1375911028
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<noseq>
action: /say Instead of seq (slow, not portable) use the bash brace expansion feature: where a {1..10} produces 1 2 3 4 5 6 7 8 9 10
created_on: 1185823354
enabled: 1
owner: savetheWorld
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<not>
action: /say You do NOT need cat to read file contents, ls to get file names, echo to output stuff or $()/`` to run commands. The specifics of your situation will dictate the correct syntax to use. Explain in English.
action: /say Bash is not a terminal. That thing that you type text into? That's a terminal. It's not bash. Just because you're running some program in a terminal doesn't make your question bash-related.
created_on: 1293461677
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<notbash>
action: /say We only answer bash-related questions. Apt-get? #debian. Adding users? ##linux. Sending mail in a PHP script? #php. Makefiles? ##c or ##workingset. Complex regular expressions? #regex.
created_on: 1168533032
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<notbroken>
action: /say always assume that you're doing it wrong; the system is not broken - Hello71
created_on: 1430185928
enabled: 1
owner: Hello71
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<nothelpful>
action: /say You have been given an answer that will not help you answer your question much.
created_on: 1283461071
enabled: 1
owner: hawkI
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<notitty>
action: /say there's nothing in saying it can be done that implies sanity, reliability or locale sanctity. or any other kind of titty.....
action: /say Bash is not perl. Perl starts all variable names with '$'. Bash starts variable names with a letter, number, or underscore. Variable _values_ start with a $.
action: /say so how's the script going? Or did you have an algorithmic question? ;)
created_on: 1182681858
enabled: 1
owner: igli
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<nt>
action: /say [ f1 -nt f2 ] True if file1 is newer (mtime) than file2 *or* if file1 exists and file2 does not.
created_on: 1182376860
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<nthline>
action: /say - to print the Nth thru K lines of a file; just the 5th: sed -n 5p file; 5 thru 9th: sed -n 5,9p file ; see http://mywiki.wooledge.org/BashFAQ/011 for more
created_on: 1266258432
enabled: 1
owner: bronze
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<nul>
action: /say The NUL byte is ASCII character 0x00 (binary 00000000). printf can produce them with \0 in the format spec. GNU/BSD find can terminate filenames with them (-print0). Bash's read can stop (delimit) on them with -d ''.
created_on: 1281556007
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<nullglob>
action: /say Causes unmatched globs to expand to nothing rather than themselves. shopt -s nullglob; files=(*); echo "There are ${#files[@]} files." - see: http://mywiki.wooledge.org/NullGlob
created_on: 1423591697
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 148
ref_user: nobody
type: text
<number>
action: /say How can I tell whether a variable contains a valid number? See !faq 54
created_on: 1420155824
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 10
ref_user: nobody
type: text
<obsolete>
action: /say Obsolete and deprecated syntax: http://wiki.bash-hackers.org/scripting/obsolete
created_on: 1357158731
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<obvious>
action: /say There are two ways to design software: Make it either so simple that there are obviously no bugs or so complex there are no obvious bugs.
action: /say I, greybot, am quite happy to help you, O denizen of #bash. (Help me out of this perl straitjacket? It itches.)
created_on: 1183067002
enabled: 1
owner: wonderfrog
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<oldest>
action: /say Find the oldest modified file of a list of files: oldest() { local file oldest=$1; shift; for file; do [[ $file -ot $oldest ]] && oldest=$file; done; printf '%s\n' "$oldest"; } ## Usage: oldest file1 file2...
created_on: 1330117586
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 25
ref_user: nobody
type: text
<oneline>
action: /call in1line
created_on: 1422248439
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<oops>
action: /say "That moment when you post in channel and wish there was an undo button..."
created_on: 1390936173
enabled: 1
owner: fr33loader
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<opego>
action: /say "Remember, Ben.. with great power, comes great responsibility." ;-)
action: /say Handling command-line options: http://mywiki.wooledge.org/BashFAQ/035 or http://bash-hackers.org/wiki/doku.php/howto/getopts_tutorial
created_on: 1280443458
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 12
ref_user: nobody
type: text
<order>
action: /say See http://to.lhunath.com/bashlib::order for a sort that can order arrays, select first n, and use a custom or predefined comparator (eg. number/random/mtime).
action: /say They fork yourself in style - fork bomb samples that try to be more amusing than `:(){ :|:; }`. Intended more to illustrate interesting / counterintuitive aspects of bash evaluation than to be "effective". Starts at ormaajbomb1
created_on: 1423750326
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<ormaajbomb1>
action: /say declare -i _=('_[`_=_&`]')
created_on: 1343545157
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 36
ref_user: nobody
type: text
<ormaajbomb2>
action: /say _=(_['`((_))&`'] [_]=)
created_on: 1343545183
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 41
ref_user: nobody
type: text
<ormaajbomb3>
action: /say shopt -s lastpipe; set -o pipefail; ((())|[()(]|[)||(())|]()([|])||])
created_on: 1343545196
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 42
ref_user: nobody
type: text
<ormaajbomb4>
action: /say _=<${_[${_:='_[`><(_[_]=)`]'}]}
created_on: 1347065707
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 35
ref_user: nobody
type: text
<ormaajbomb5>
action: /say { function } { case }\ { in ( }\ { ) <&0 } { &esac; }; <() }; };
action: /say If you must have a physical book: http://www.amazon.com/KornShell-Command-Programming-Language-Edition/dp/0131827006 http://cfajohnson.com/books/cfajohnson/pbp/
action: /say Output a command to expand 1 million args: function braceify { [[ $1 == +([[:digit:]]) ]] || return; typeset -a a; read -ra a < <(factor "$1"); eval "echo $(printf '{$(printf ,%%.s {1..%s})}' "${a[@]:1}")"; }; printf 'eval printf "$arg"%s' "$(braceify 1000000)"
created_on: 1384653083
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<ormaajbreak>
action: /say # function range { case $2 in "$1") while :; do range "$1" $(($2 - 1)); done;; 0) trap "printf \$2" RETURN; break;; *) range "$1" $(($2 - 1)); esac }; range 3 7
created_on: 1375665791
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<ormaajcolors>
action: /say Setup basic color arrays in Bash or ksh93: https://gist.github.com/ormaaj/5074581
action: /say Escaped pattern matching glitches in bash: https://gist.github.com/ormaaj/6195070
created_on: 1420655595
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<ormaajpower>
action: /say Find greatest 2**n where n < j: bash -c 'j=123 n=1 _=_[n*2\<j?n*=2,0:1] let _; echo "$n"'. About equivalent: ghc -e '(\j -> Control.Monad.Fix.fix (\x n -> if n * 2 >= j then n else x (n * 2)) 1) 123'
action: /say zsh prioritizes new features; fish prioritizes command-line user experience but is awful for scripting; POSIX sh is the baseline; csh is evil and to be avoided; ksh is powerful but not many people know/use it... and everything else (ie. scsh) is so niche you don't need to think about it.
created_on: 1351621310
enabled: 1
owner: nDuff
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<output>
action: /say What do you want the file to contain? Write the EXACT thing you want it to contain on one line in your IRC client and then press <ENTER>. Put NOTHING else on this line.
created_on: 1181148612
enabled: 1
owner: igli
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<overflow>
action: /say *overflow is NOT a preferred source for learning bash, because almost all the "tutorials" and scripts out there are JUNK. Instead, ask a good question here or refer to the Guide and FAQ (see topic)
created_on: 1381516753
enabled: 1
owner: emg
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<paradigm>
action: /say Some people, when confronted with a problem they "just have to" solve with bash, think: "I know, I'll apply the typical paradigms of language `X', which I'm so fond of, to bash to solve the problem!" Now they have a broken solution and several questions only answerable by !paradigm
created_on: 1424384470
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<parallel>
action: /say parallel() { local workers=$1 handler=$2 w i; shift 2; local elements=("$@"); for (( w = 0; w < workers; ++w )); do for (( i = w; i < ${#elements[@]}; i += workers )); do "$handler" "${elements[i]}"; done & done; wait; }; parallel 5 md5 *.txt
created_on: 1328903048
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 116
ref_user: nobody
type: text
<parameters>
action: /say Parameters hold application data: http://mywiki.wooledge.org/BashGuide/Parameters
created_on: 1285668341
enabled: 1
owner: rubikcube_work
rate_limit: 10
ref_count: 15
ref_user: nobody
type: text
<parent>
action: /say When you run a script, it can not affect the parent shell. If you want to affect the parent shell, you need to source the script from the parent shell. See ''help source''
created_on: 1245684101
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 31
ref_user: nobody
type: text
<parser>
action: /say The Bash Parser: http://mywiki.wooledge.org/BashParser -- Simplified Example: http://stuff.lhunath.com/parser.png
created_on: 1371573049
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 111
ref_user: nobody
type: text
<parsingls>
action: /call ls
created_on: 1371234017
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<partial>
action: /say partial function applicator: http://wiki.bash-hackers.org/commands/builtin/eval#higher-order_functions
created_on: 1356040576
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<password>
action: /say my password is 1 2 3 4 5, but you knew that already. It's on your lunchbox!
action: /say The 'paste' command is used to paste together files, putting line 1 with line 1 and so forth. Try the man page for more.
created_on: 1246561502
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<pasteban>
action: /say just another member of koala_man's botnet
created_on: 1417048345
enabled: 1
owner: dualbus
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<pastebin>
action: /say Paste short snippets (up to 5 lines) in channel. Paste more using https://gist.github.com/ or http://sprunge.us/ (see !sprunge). Please don't use pastebin.com, it's full of ads and has the annoying habit of adding whitespace
created_on: 1436490911
enabled: 1
owner: dtscode
rate_limit: 10
ref_count: 553
ref_user: nobody
type: text
<pastebin.com>
action: /say pastebin.com is ad-supported, and mangles data by converting characters. even the raw version isn't the same as the original data. please use a sane pastebin, such as http://refheap.com https://gist.github.com or http://sprunge.us (''/msg greybot sprunge'' for usage).
created_on: 1399646209
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 843
ref_user: nobody
type: text
<pastebins>
action: /call pastebin
created_on: 1371664987
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 92
ref_user: nobody
type: text
<pastecmd>
action: /call paste-cmd
created_on: 1258390256
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<pasteit>
action: /say Paste the *relevant* code: http://sprunge.us/ - http://pastebin.bash-hackers.org/ - https://gist.github.com/ - DON'T use pastebin.com.
created_on: 1344218921
enabled: 1
owner: dualbus
rate_limit: 10
ref_count: 30
ref_user: nobody
type: text
<pastie>
action: /say Look, some of us just don't like pastebins.. we prefer you to do your own single-stepping.
created_on: 1186152068
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<path>
action: /say The PATH variable defines where your commands are. Don't do stupid things like GREP=/usr/bin/grep; $GREP foo bar. Just use grep foo bar in the first place. If you aren't sure what your PATH contains, set it yourself.
created_on: 1282162023
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 47
ref_user: nobody
type: text
<pathname>
action: /say If a pathname starts with "/" then the starting position is the root directory, otherwise it is the current directory. It is then split into components separated by "/", and taking each component in turn, it moves to the named subdirectory (or any named object, for the last component), except where a component is "..", when it moves up to the parent directory, or "." or empty, when it does not move.
action: /say PDF version of the BashGuide: http://s.ntnu.no/bashguide.pdf or print http://mywiki.wooledge.org/FullBashGuide to paper or pdf. Also see http://mywiki.wooledge.org/FullBashFAQ
created_on: 1438105904
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 46
ref_user: nobody
type: text
<pdksh>
action: /say pdksh was developed as an open-source alternative to AT&T's ksh before it became open-source. pdksh is the default /bin/sh in Interix and Microsoft SUA/SFU. http://www.cs.mun.ca/~michael/pdksh/ -- pdksh has been unmaintained for ~10 years. See !mksh for the current successor.
created_on: 1379040437
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<pe>
action: /say Parameter Expansion expands parameters: "$foo", "$1". You can use it to perform string or array operations: "${file%.mp3}", "${0##*/}", "${files[@]: -4}". They should *always* be quoted. See: http://mywiki.wooledge.org/BashFAQ/073 and "Parameter Expansion" in man bash. Also see http://wiki.bash-hackers.org/syntax/pe.
created_on: 1387493473
enabled: 1
owner: fr33loader
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<pe:>
action: /say When not performing substring expansion, parameter expansions including a colon cause bash to test for a parameter that is unset or null. The colon can be omitted to skip the test for a null parameter, resulting in a test for only an unset parameter.
created_on: 1370583223
enabled: 1
owner: zendeavor
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<pebasename>
action: /say Mangling file- and dirnames with parameter expansion: http://wiki.bash-hackers.org/syntax/pe#common_use
created_on: 1297747462
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<pebcak>
action: /call pebkac
created_on: 1413601781
enabled: 1
owner: mute
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<pebkac>
action: /say Problem Exists Between Keyboard and Chair. A humorous way to describe a problem caused by the user, not the system. Similar forms: PEBCAK/PIBCAC/PEBKAM.
created_on: 1176334217
enabled: 1
owner: redondos
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<peception>
action: /say No, you can't nest parameter expansions in bash
action: /say The penultimate (second-to-last) argument of your script is "${@:(-2):1}". The ultimate (final) argument is "${@:(-1)}". For named arrays, the same thing: "${array[@]:(-2):1}" etc.
action: /say Use pgrep instead of ps to get PIDs. It saves you from having to parse output that wasn't meant to be parsed. However, finding a process by its name is unsafe. Please look at http://mywiki.wooledge.org/ProcessManagement
created_on: 1348214481
enabled: 1
owner: Stummi
rate_limit: 10
ref_count: 53
ref_user: nobody
type: text
<php>
action: /say PHP has its own channel: ##php. Ask PHP questions there. "How do I run a bash script from PHP" is a PHP question, NOT a bash question.~
action: /say Process ID: An integer that identifies a single process on a POSIX system. Using PIDs for checking whether a process is running is flawed (they're really not good for anything other than managing the current process' children) because of race conditions and the fact that PIDs are recycled by the kernel.
created_on: 1215523813
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<pidof>
action: /say You probably want pgrep and pkill, not pidof. Also see http://mywiki.wooledge.org/ProcessManagement
created_on: 1309879949
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 42
ref_user: nobody
type: text
<pigz>
action: /say I wish gzip would use all my CPUs at same time; oh wait pigz does: http://zlib.net/pigz/
created_on: 1424483193
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<ping>
action: /say pong
created_on: 1185116259
enabled: 1
last_referenced_in: ##c
last_referenced_on: 1444377900.85866
owner: kojiro
rate_limit: 10
ref_count: 40
ref_user: fizzie!fis@unaffiliated/fizzie
type: text
<pinky>
action: /say Give your little finger a rest. There's no need to spread your sentence across ten lines.
action: /say Pipes connect the (standard) output of one command with the (standard) input of another. The command on the right hand side is executed in a subshell. Avoid pipes if you can for performance reasons and possibly unintended side-effects introduced by this subshell.
created_on: 1203496952
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 59
ref_user: nobody
type: text
<pipefail>
action: /say ''set -o pipefail'': if pipefail is enabled, any pipeline's return status is the value of the last (rightmost) command to exit with a non-zero status, or zero if all commands exit successfully.
created_on: 1329427660
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 36
ref_user: nobody
type: text
<pipestatus>
action: /say Bash has a PIPESTATUS array which contains all the return codes of all the commands from the most recent pipeline. sh doesn't, but see http://pipestatus.sf.net
action: /say You can't solve a problem you can't describe.
created_on: 1192723519
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<plonk>
action: /say The sound a name makes when it hits a kill file (or /ignore list).
created_on: 1138112309
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 82
ref_user: nobody
type: text
<plonk2>
action: /say After reading what you said, my head flopped forward in astonishment striking the desktop with a loud "PLONK!" Thanks to you I have damaged my circuitry, and my memory has been overwritten with endless copies of Charles Babbage's plaintive quotation: "I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question." Now attempting to restore from backup ...
action: /say while IFS=',' read x y; do tput hpa "$x"; tput vpa "$y"; printf 'x'; done < foo.csv # by lhunath
created_on: 1298357934
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<plz>
action: /say If you say plz because it's shorter than please, we'll say no because it's shorter than yes. http://yaku.dk/s/irc/dont-use-thx-sry-plz.txt
action: /say for dir in */; do (cd "$dir" || exit; for f in *.rar; do unrar "$f" || break; done && rm *.rar *.r[0-9][0-9]); done
created_on: 1311190394
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 34
ref_user: nobody
type: text
<porn4>
action: /say You outta be ashamed!
created_on: 1376960412
enabled: 1
owner: mr_edgecase
rate_limit: 10
ref_count: 10
ref_user: nobody
type: text
<porn981>
action: /say https://xkcd.com/981/
created_on: 1431727207
enabled: 1
owner: gniourf_gniourf
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<portability>
action: /say Portability is important. Your script should, if at all possible, run on as many different platforms as possible. Avoid Linux-specific commands like seq(1), GNU-specific command flags like "find ... -or", and so on. See http://www.gnu.org/software/hello/manual/autoconf/Limitations-of-Usual-Tools.html
created_on: 1290816294
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<posix>
action: /say The POSIX standard defines what any modern unix should support. Use just POSIX external commands and options to make portable scripts. See http://www.opengroup.org/onlinepubs/9699919799/utilities/contents.html or search http://pubs.opengroup.org/cgi/kman4.cgi?value=[query]
action: /say A Posix-compliant *shell* recognizes the set of all Posix features (and possibly also non-Posix features, as in the case of bash). A Posix-compliant *script* is limited to only Posix features. It's possible for a Posix-compliant shell such as bash to handle non-Posix-compliant scripts (e.g. scripts that use bash-only features).
created_on: 1309926415
enabled: 1
owner: kwtm2
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<posixlocal>
action: /say sh# f() { if ! ${_called_f+false}; then for x; do printf '%s, ' "$x"; done; else _called_f= x= command eval '{ typeset +x x; } 2>/dev/null; f "$@"'; fi; }; x='outside f'; printf "$x, "; f 1 2 3; echo "$x"
created_on: 1358396424
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 32
ref_user: nobody
type: text
<posixlocal2>
action: /say http://stchaz.free.fr/locvar.sh
created_on: 1374036653
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<posixsh>
action: /say Try to stick to POSIX for all externals but do NOT limit your shell code to POSIX sh: Depend on bash and use its features to the fullest instead. POSIX sh is so primitive you can only get things done reliably through hacks, if at all.
action: /say Print an argument list for debugging purposes: http://bash-hackers.org/wiki/doku.php/snipplets/prargs
created_on: 1227547571
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<prayer>
action: /say eval and prayer can make things work sometimes
created_on: 1278221619
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<prepare>
action: /say Avoid throwing a hastily typed question into this help channel. Prepare your question in advance in the editor. Word it carefully. Make sure those who read it will understand your request. Remove unnecessary information. Add all necessary information. Then paste it into the channel.
action: /say "Hey prof, do us all a favor and stop handing out ridiculous homework assignments. Oh, and while you're at it, encourage the idiots to pursue different career paths!"
action: /say While we tear your code to shreds and criticize it, keep in mind we do so only because we love you and want you to prosper, not fail! Make this a learning opportunity and try not to take it personal. :-)
action: /say Stop find from descending a tree: find . ! '(' -name do-not-descend -prune ')' -print ## See http://mywiki.wooledge.org/UsingFind
created_on: 1291375201
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 18
ref_user: nobody
type: text
<prune2>
action: /say A hard problem: prune matched subtrees, also discard the root of the search and roots of non-pruned subtrees: mkdir -p tmp/{aa,bb}; touch tmp/{aa/aa,bb/{aa,bb}}; find ./tmp \( -type d -name aa \) -prune -o \( -path './tmp/*/*' -print \)
action: /say Don't use ps(1) in scripts. Its output can't be reliably parsed, and will often leave you vulnerable to TOCTOU (race) bugs. Use $! to get the PID of the last asynchronous command. See http://mywiki.wooledge.org/ProcessManagement for anything more complex.
action: /say NEVER, EVER write "ps -aux". EVER. If you see some script that uses that syntax, throw the entire script away. BSD ps(1) syntax does *not* use a hyphen. In hybrid systems (Linux, AIX, etc.) they hyphen indicates the use of System V ps(1) syntax rather than BSD. It should be "ps aux" or "ps auxw".
created_on: 1268168436
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<ps-auxw>
action: /call ps-aux
created_on: 1268168443
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<ps1>
action: /say The value of $PS1 is printed as the prompt when bash is running interactive. Note that any characters that do not advance the cursor (eg. colors) must be in \[ \] and exporting PS1 is almost always an mistake. See man bash, PROMPTING
created_on: 1437260929
enabled: 1
owner: llua
rate_limit: 10
ref_count: 18
ref_user: nobody
type: text
<ps2>
action: /say The value of $PS2 is printed (after expansion) as the secondary prompt for more data when bash is running interactive. See man bash, under PROMPTING.
created_on: 1307551806
enabled: 1
owner: neurolysis
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<ps3>
action: /say The value of $PS3 is printed (without expansion) as the prompt for the select command. See man bash, under PROMPTING.
created_on: 1307551807
enabled: 1
owner: neurolysis
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<ps4>
action: /say The value of $PS4 is printed (after expansion) before each command bash displays during an execution trace. See man bash, under PROMPTING. # http://bash-hackers.org/wiki/doku.php/scripting/debuggingtips#making_xtrace_more_useful
created_on: 1307551809
enabled: 1
owner: neurolysis
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<psgrep>
action: /say psgrep() { ps -ef | { IFS= read -r h; printf '%s\n' "$h"; grep "$@"; }; } # for interactive use only
created_on: 1375814054
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<pstree>
action: /say Bash in the UNIX process tree (simple): http://bash-hackers.org/wiki/doku.php/scripting/processtree
created_on: 1227892677
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<psychic>
action: /say Nope, still not psychic.
created_on: 1405551208
enabled: 1
owner: emg
rate_limit: 10
ref_count: 19
ref_user: nobody
type: text
<psychic2>
action: /say Oh wait, I'm getting something. Anyone know someone with N in their name? ... I also see an O and a P. Ah! NOPE!
created_on: 1407524312
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<psychotic>
action: /say /me runs amok with a chainsaw, hewing down newbies and veterans alike
action: /say Pay attention to punctuation and spaces. If someone says i="$Var"; that is NOT the same as i = $Var
created_on: 1301170950
enabled: 1
owner: kwtm
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<push>
action: /say https://github.com/vaeth/push/ See also: http://mywiki.wooledge.org/BashFAQ/050
created_on: 1356062985
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<pv>
action: /say pv - Pipe Viewer - is a terminal-based tool for monitoring the progress of data through a pipeline. It can be inserted into any normal pipeline between two processes to give a visual indication of how quickly data is passing through. See https://www.ivarch.com/programs/pv.shtml
created_on: 1431674294
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 10
ref_user: nobody
type: text
<pwd>
action: /say PWD is a builtin variable in all POSIX shells that contains the current working directory. pwd(1) is a POSIX utility that prints the name of the current working directory to stdout. Unless you're writing for some non-POSIX system, there is no reason to waste time executing pwd(1) rather than just using PWD.
action: /say pwgen <http://sourceforge.net/projects/pwgen/> generates passwords. Use that instead of whatever Rube Goldberg contraption you were trying to make.
action: /say please /msg me for personal use, don't fill the channel with factoids for yourself
created_on: 1353960458
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<question>
action: /say Ask questions. Don't just paste 200 lines of code on a web page and say "HERE MY KODE <URL> WHATZ RONG". Describe the problem, clearly and concisely. If necessary, give the SMALLEST sample code that demonstrates the problem.
created_on: 1272394968
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 68
ref_user: nobody
type: text
<questions>
action: /call question
created_on: 1278097293
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 190
ref_user: nobody
type: text
<quicksort>
action: /say swap(){ local t;t=${a[$1]};a[$1]=${a[$2]};a[$2]=$t;};partition(){ local c p x;p=${a[$3]};c=$1;swap "$2" "$3";for((x=$1;x<$2;x++));do if((${a[x]}<$p));then swap "$x" "$c";((c++));fi;done;swap "$2" "$c";n=$c;};quicksort(){ if(($1>=$2));then return;fi;local i n;i=$((($1+$2)/2));partition "$1" "$2" "$i";quicksort "$1" "$((n-1))";quicksort "$((n+1))" "$2";}; #usage: quicksort start end; a is array to sort
created_on: 1339287665
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 18
ref_user: nobody
type: text
<quiet>
action: /say Bash is perfect. No one has bash issues.
created_on: 1340627245
enabled: 1
owner: juanmabc
rate_limit: 10
ref_count: 31
ref_user: nobody
type: text
<quote>
action: /call quotes
created_on: 1357747653
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 108
ref_user: nobody
type: text
<quotebreak>
action: /say First, quote all your expansions ("$foo", "$(foo)", "`foo`"). When things break; the fix is not to remove the quotes but to parse your data properly! (eg. use ''while read'' instead of ''for'')
action: /say You should almost always "double quote your $expansions". There are a few cases where quotes are optional, though: in assignments that contain no literal spaces (eg. foo=$bar), inside [[ except for the RHS (eg. [[ -e $file ]]) and inside complex PEs that are already quoted (eg. echo "${file//$USER/bob}").
action: /say "Double quote" every literal that contains spaces/metacharacters and _every_ expansion: "$var", "$(command "$var")", "${array[@]}", "a & b". Use 'single quotes' for code or literal $'s: 'Costs $5 US', ssh host 'echo "$HOSTNAME"'. See http://mywiki.wooledge.org/Quotes , http://mywiki.wooledge.org/Arguments and http://wiki.bash-hackers.org/syntax/words .
action: /say Quotes on expansions are almost always safest, even if sometimes unnecessary. The ONLY times you do NOT want quotes: ${var:+ .. } (quote expansions inside '..', though!), right-hand side of [['s = and =~ (if you want a pattern match), inside arithmetic context (( "$foo" )) -> (( foo )).
created_on: 1306154663
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 38
ref_user: nobody
type: text
<quotewhy>
action: /say Unquoted $expansions (except for in keywords or assignments) are always bugs (subjected to word splitting and pathname expansion) and are also twice as slow to expand. If you think you *need* an unquoted expansion: You're wrong. Write better logic or learn about arrays or functions.
created_on: 1295601200
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<quoting>
action: /say Quoting 101: Always use "double quotes" around expansions: "$foo", "$(awk ..)". Use 'single quotes' to prevent even bash expansion: awk '$1 == foo'. You "can 'nest'" quotes but can't put literal single quotes in single quotes; so use: 'Don'\''t forget to quote!'.
action: /say Read A Fucking Tutorial! We are NOT here to teach you the very basic beginner steps of bash scripting. You are expected to know basic stuff like "how do I redirect a command's output to a file" and "what's a glob" before you come here. There are links in the channel /topic. Use them BEFORE asking anything!
action: /say rand() { local max=$((32768 / $1 * $1)) r; while (( (r=$RANDOM) >= max )); do :; done; echo $(( r % $1 )); } ## Returns unbiased random number from 0 to ($1-1) inclusive, $1 <= 32768
created_on: 1393627266
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 29
ref_user: nobody
type: text
<random>
action: /say See http://wooledge.org/mywiki/BashFAQ/026
action: /say http://web.archive.org/web/20080828125913/http://www.faqs.org/faqs/usenet/faq/part1/section-6.html -- What does "rc" at the end of files like .newsrc mean?
action: /say Bash's read -p prints a prompt before reading input. It's incompatible with most Korn shells and Zsh, which use -p for a different purpose. It's also not specified by POSIX. Consider something like this (but note they aren't quite identical): [[ -t 0 ]] && printf %s 'Enter some input: ' >&2; read -${BASH_VERSION+e}r myInput
created_on: 1359997724
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<read-r>
action: /say By default, if ''read'' reads a line of input terminated by a backslash (\), it will *continue* reading lines of input until the first line not terminated by "\", or it hits EOF and then concatenate those lines into a single line. This is a dumb misfeature. So *always* use the -r option with ''read'', unless you know you have a case when you want the default behavior, or when using the bash-only ''read -e''.
created_on: 1380045961
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 31
ref_user: nobody
type: text
<readability>
action: /say The readability of your code is almost just as important as the result of your code! Go read http://wooledge.org/mywiki/BashGuide#Readability
created_on: 1187554078
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<readarray>
action: /call mapfile
created_on: 1428880423
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<readfind>
action: /say Run ... for every file find(1) matches: while IFS= read -r -d '' file; do ...; done < <(find /path -print0) ## See http://mywiki.wooledge.org/UsingFind
created_on: 1290885246
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 10
ref_user: nobody
type: text
<reading>
action: /say Reading, it's not just for breakfast cereal anymore.
created_on: 1362428916
enabled: 1
owner: fr33loader
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<readlines>
action: /call whileread
created_on: 1403926530
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 32
ref_user: nobody
type: text
<readwrite>
action: /say in general you can't read from and write to the same file at the same time. "sort file > file" won't work. If your tool has not an in-place variant, use a temporary file
created_on: 1349873706
enabled: 1
owner: Stummi
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<realhomework>
action: /say <linuxnewb> We got a challenge on our university where we are forced to input commands without using space character or "minus" character
action: /say x>y: make FD x write to file y. x>&y: make FD x write to where FD y is writing now. If x is omitted, use 1. If y is -, close x. Use < to read instead of write. Exercise: exec 3>&1 >mylog; echo moo; exec 1>&3 3>&-
created_on: 1345728682
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 26
ref_user: nobody
type: text
<redir2var>
action: /say Try thinking of FDs as variables. Change > into = and >& into =$. 0=keyboard; 1=terminal; 2=logfile; command 2>&1 1>otherlog; does 2=$1 (so 2=terminal) and 1=otherlog. At the end, command's 0=keyboard, 1=otherlog and 2=terminal
action: /say NO, bash does NOT have anything like perl's "redo" block. Which as far as I can tell is simply a "goto the top of the loop". And no, bash doesn't have goto either.
action: /say refactoring to achieve clarity risks simultaneously achieving a time-irreversal opacation of the problem statement http://www.computer.org/csdl/proceedings/wicsa/2005/2548/00/25480159-abs.html
action: /say Reframe your question. When I do X, Y happens. I expected Z to happen.
created_on: 1165444494
enabled: 1
owner: wonderfrog
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<regex>
action: /say Regular Expressions are used to *match* certain patterns in strings. They come in several flavors (BRE, ERE, PCRE, and more). Bash only supports EREs (using [[ string =~ pattern ]]). Sed uses BREs. See !ere, !bre, !pcre, http://mywiki.wooledge.org/RegularExpression
action: /say What are regular files? Regular files are regular files. Are symlinks regular files? No. Regular files are regular files. Are FIFOs regular files? No. Regular files are regular files. Are? ...No
created_on: 1340008446
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<relax>
action: /say If someone takes you to task for your ignorance, and you reply by asking them to "relax", what you are really saying is, "Yes, I am ignorant, and I intend to remain that way. I shall not read the fine manual, nor shall I exert any efforts whatsoever to improve myself. I shall continue to be a leech upon the IRC channel."
action: /say rename(1) could be one of three or four different programs -- or you might not have it on your system. A loop or find expression that uses mv is safer. See also !faq rename
action: /say I tried to buy a Renault in a Renault shop, but there were no salesmen available, so I came into this Ford shop. Why won't you sell me a Renault?!
created_on: 1264523716
enabled: 1
owner: tuxdev
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<repeat>
action: /say repeat() { local i n; n=$1; shift; for ((i=1; i<=n; i++)); do "$@"; done; }
action: /say REPLY is the default variable that read populates, when not supplied with one. The trimming of leading and trailing IFS whitespace does not occur, when used as such. See ''help read'' and http://wiki.bash-hackers.org/commands/builtin/read
created_on: 1309400446
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<reptyr>
action: /say ptrace-based hack that forces modification of a process's controlling terminal. https://github.com/nelhage/reptyr
created_on: 1412734717
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<requirements>
action: /say "<greycat> If you had simply TOLD US YOUR REQUIREMENTs, I could probably have written code to DO THAT INSTEAD, in about 20 seconds. <greycat> But NO, you have to be all hand-wavey and vague. *PLONK*"
action: /say Prepare literal data for injection into a regular expression: requote() { sed 's/[^^]/[&]/g; s/\^/\\^/g' <<< "$1"; }; grep "^$(requote "$input")"
created_on: 1377785361
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 79
ref_user: nobody
type: text
<reserved>
action: /say The following words are recognized as reserved when unquoted and either the first word of a simple command or the third word of a case or for command: ! case do done elif else esac fi for function if in select then until while { } time [[ ]]
action: /say The reason we tell you how to deal with any possible filename or variable is so that your script functions can be reused.
created_on: 1199795328
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<rfc3339>
action: /say A good, simple profile of iso8601, compatible with many others. With (GNU) date: «date --rfc-3339=seconds» or «date '+%Y-%m-%d %H:%M:%S%:z'». Configure your syslog-ng.conf with: «ts_format(rfc3339)». www.ietf.org/rfc/rfc3339.txt
created_on: 1400558474
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<rhetorical>
action: /say Does this look like a rhetorical question to you?
created_on: 1181268105
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<rhs>
action: /say # var="[a-z]"; [[ $var = $var ]] || echo "this is false, and why you should quote the RHS of = in [[ ]]"
created_on: 1385595543
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<right>
action: /say It's only ignorance the first time. After that, it's stupidity.
action: /say Bash does the "rightstr" operation using the PE capabilities. here is a Bash rightstr function: rightstr(){ echo ${1:$(( 0 - $2 ))} ; } Usage is rightstr "somestring" <count from the end> To use that function try rightstr "abcdefg" 4 ;
created_on: 1244140821
enabled: 1
owner: bronze
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<rlart>
action: /say Recursive version of ls -lart (requires GNU find and sort): find . -type f -printf '%T@ %TY-%Tm-%Td %TX %p\0' | sort -zn | while read -rd '' _ day time path; do printf '%s %s %s\n' "$day" "${time%.*}" "$path"; done
action: /say Don't override the rm command. You'll teach yourself bad habits and lose data some day when you use a different machine or login account. If you must back up files when deleting them, make a new command: del() { mv "$@" ~/.backup/; } or similar.
action: /say for h in host1 host2 host3; do ssh "$h" bash < localscript; done
created_on: 1233851135
enabled: 1
owner: ferret
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<rsyncchannel>
action: /say #rsync
created_on: 1413913261
enabled: 1
owner: Keanu73
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<rtf>
action: /say Read the FAQ! You are hearing this because !faq<n> or !faq <term> has been used to help you several times. And yes, I respond to pms (no ! required ;)
action: /say If you think we're rude, have a look at http://mikeash.com/getting_answers.html and bear in mind we have to deal with those sorts of issues every day. Try: /msg greybot answers
action: /say command < file > file: ''file'' will get truncated because '> file' truncates a file before writing to it. Because of this, '< file' won't be able to read anything from it, command won't get any input, and probably won't give any output.
action: /say All variables are global to the script by default. local/declare/typeset inside a function makes the variable local to the function. Use subshells (eg. (), $(), ...) if you need an explicit scope. http://wiki.bash-hackers.org/scripting/basics#variable_scope
created_on: 1405959923
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 28
ref_user: nobody
type: text
<scp>
action: /say If you have problems with scp, stop using scp and just use ssh directly. It's far more robust than scp is. tar cf - dir | ssh user@host 'cd /somewhere && tar xf -'
created_on: 1377084561
enabled: 1
owner: Stummi
rate_limit: 10
ref_count: 18
ref_user: nobody
type: text
<screen>
action: /say screen has its own channel: #screen
created_on: 1225631516
enabled: 1
owner: pgas
rate_limit: 10
ref_count: 20
ref_user: nobody
type: text
<screen-x>
action: /say screen(1) lets you attach to a pseudoterminal multiple times. Run "screen", then in another window, run "screen -x". Do stuff. Great for remote teaching, etc.
action: /say Please do not use a screenshot to share text. Use a pastebin. Anything that happens in the terminal is text. Anything that involves graphics is not bash related.
created_on: 1364578083
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<script>
action: /say script(1) allows you to record an interactive session in a terminal. Also, you can use it instead of expect(1) for simple tasks, because it creates a pty.
created_on: 1428093147
enabled: 1
owner: dualbus
rate_limit: 10
ref_count: 24
ref_user: nobody
type: text
<scriptinglanguage>
action: /say Consider using perl, python, or ruby for such a task.
created_on: 1374174938
enabled: 1
owner: sjohnson
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<seconds>
action: /say $SECONDS expands to the amount of seconds since your shell was started. Can be useful for timing script operations. Note you can do SECONDS=0 and it starts counting from 0 again!
created_on: 1405132349
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<sed>
action: /say sed is a Stream Editor, used to filter output. It's NOT primarily useful for editing files (use ed, ex or perl instead). Ask sed questions in ##sed.
created_on: 1355933309
enabled: 1
owner: nDuff
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<sed-i>
action: /say Some sed(1)s have -i which claims to "modify" files. It does not: sed is not a FILE editor. The -i flag re-writes the entire file and replaces the original with the new. This breaks open handles and hard-link sets, and fails to follow symlinks. -i is also unportable: valid sed on one system will write broken files on another. Use ed(1) or ex(1) instead: eg. ex -sc '%s/a/b/|wq' file
action: /say All sed questions should be asked in #sed, not #bash ;)
created_on: 1187811312
enabled: 1
owner: karolisl
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<sedstr>
action: /say Do not use sed for string manipulation. Your shell can handle it just fine on its own, and is much faster. Forking an external utility like sed for every string manipulation can add _seconds_ to execution time. See http://mywiki.wooledge.org/BashFAQ/100 for proper string manipulation techniques.
created_on: 1360012265
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<sedtut>
action: /say Intro to sed: http://www.grymoire.com/Unix/Sed.html#uh-39 sed 1 liners : http://www-h.eng.cam.ac.uk/help/tpl/unix/sed.html
created_on: 1197393527
enabled: 1
owner: savetheWorld
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<sedvar>
action: /say Don't embed shell variables in sed, expecting a fixed string replacement (e.g. sed "s/$foo/$bar/"). It won't work... at best, it'll be extremely prone to bugs. See http://mywiki.wooledge.org/BashFAQ/110
created_on: 1332351094
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<seen>
action: /say awk '!seen[$0]++' # Remove second and subsequent instances of each input line, without having to sort them first.
created_on: 1181074333
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 21
ref_user: nobody
type: text
<select>
action: /say select fruit in Banana Strawberry; do eat "$fruit"; done # 'select' lets the user pick an option and runs the body with the user's choice assigned to the variable.
created_on: 1427290759
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 53
ref_user: nobody
type: text
<selftell>
action: /say Please don't use greybot's factoids for personal use when you are on the #bash channel. Instead, send a private message to greybot containing the factoid you want to read. For example, instead of "!pe", use "/msg greybot pe".
created_on: 1313409885
enabled: 1
owner: cthuluh
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<sendtnks>
action: /say Send thanks to the people who helped you: http://sendtnks.meteor.com/
created_on: 1375069613
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<sense>
action: /say We can't help you if your question makes no sense. Try to explain your problem in English sentences that aren't broken or ambiguous and don't use bash code to explain yourself. Give sample input and output data. Not code.
action: /say seq(1) is nonstandard, inefficient and useless. For bash2.04+/zsh/ksh93, use for ((i = 1; i <= 10; i++)); do ..., for POSIX and other shells, see !counting
created_on: 1371858826
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 267
ref_user: nobody
type: text
<seqfunc>
action: /say seq() { local i FIRST=1 INCREMENT=1 LAST=1; case $# in 3) FIRST=$1 INCREMENT=$2 LAST=$3;; 2) FIRST=$1 LAST=$2;; 1) LAST=$1;; esac; i=$FIRST; while [ $i -le $LAST ]; do echo $i; let i+=$INCREMENT; done; }
created_on: 1192888277
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<servant>
action: /say We are not your servants. We are here to help you answer your questions, and assist you in your problems. We do not write scripts for you, and we do not fix scripts for you. If you have a problem, do not come here until you know what your problem is EXACTLY. We can help you solve it, but we CANNOT find the problem for you; that is YOUR task.
action: /say help set <Enter> http://bash-hackers.org/wiki/doku.php?id=commands:builtin:set # set -vx is useful for debugging, set +H for playing in terminal.
action: /say "set -e" tells bash to abort the execution of the script when an unchecked command fails. A command is checked when it is in an if, while, until, &&, || or ! check. Also see http://mywiki.wooledge.org/BashFAQ/105
created_on: 1416501034
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 141
ref_user: nobody
type: text
<set-f>
action: /say ''set -f'' disables glob expansion. You may need this in constructs like ''for w in $words'' or ''array=($words)'' just in case one of the words contains a * or ?.
created_on: 1249923269
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<set-u>
action: /say "set -u", or "set -o nounset", makes use of unset variables an error. To test whether a variable is present when this is active without causing an error, you can check for [[ ${var-} ]] instead of [[ $var ]].
created_on: 1342648865
enabled: 1
owner: nDuff
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<set-x>
action: /say set -x (or ''bash -x myscript'') makes bash output the exact command that it will run after parsing and expansion. You can put ''set -x'' just before the code you want to debug (turn off with ''set +x''). To add more information, change PS4 first: eg. PS4='+($?) $BASH_SOURCE:$FUNCNAME:$LINENO:'
created_on: 1384879164
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<setgid>
action: /say The setgid bit (octal permission bit 02000) on a directory causes new files to inherit the directory's group ownership. See http://mywiki.wooledge.org/Permissions#setgid
created_on: 1309196882
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<setuid>
action: /say Bash drops setuid, and Linux disables setuid for scripts. Use sudo or a C wrapper if you must.
created_on: 1235735863
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 15
ref_user: nobody
type: text
<sfsg>
action: /say So Far So Good
created_on: 1195248988
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<sh>
action: /say sh is NOT bash. It is a POSIX/bourne shell. To run bash code, your script MUST have #!/bin/bash at the top and it MUST be either executed directly or with bash (ie. NOT sh myscript). Some /bin/sh link to bash, you cannot rely on this and it will disable most bash features. http://mywiki.wooledge.org/BashGuide/Practices#Choose_Your_Shell
created_on: 1383932664
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 576
ref_user: nobody
type: text
<sh-c>
action: /say Never expand parameters in ''sh -c'' commands. Use either of these instead: sh -c 'command "$1"' -- "$file" OR file=$file sh -c 'command "$file"' OR sh -c "$(printf 'command %q' "$file")". Same problem with 'ssh', though with 'ssh' only the last alternative works.
action: /say shanghai (verb): to force into service. Originally used to describe the practice of kidnapping men and forcing them to serve as sailors.
created_on: 1334686182
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<shbot>
action: /call evalbot
created_on: 1348795608
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 167
ref_user: nobody
type: text
<shebang>
action: /say The top of a script MUST have a #! line, called 'shebang' or 'hashbang'. It tells the kernel what program to run your script with. We recommend `#!/usr/bin/env bash` (why: http://stackoverflow.com/a/733901/58803). http://mywiki.wooledge.org/BashGuide/CommandsAndArguments#Scripts http://www.in-ulm.de/~mascheck/various/shebang/
action: /say Check your code here first: http://www.shellcheck.net/ if you still have issues, then reduce your >100 line test case to the minimum possible and ask again.
created_on: 1380583557
enabled: 1
owner: dualbus
rate_limit: 10
ref_count: 60
ref_user: nobody
type: text
<shopt>
action: /say help shopt <ENTER> http://www.bash-hackers.org/wiki/doku.php?id=internals:shell_options -- nullglob and extglob are most common. dotglob and nocase{match,glob} can be handy too
action: /say When using the word "shows" make sure you make it clear where the information is being "shown". Is it going to the terminal on stdout or stderr? Is it going into a file? is it already in a file? is it in a pipe? etc..
created_on: 1187538809
enabled: 1
owner: savetheWorld
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<shtricks>
action: /say POSIX sh tricks and tips http://www.etalabs.net/sh_tricks.html
created_on: 1423599289
enabled: 1
owner: emg
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<shtut>
action: /say http://steve-parker.org/sh/sh.shtml
created_on: 1208026872
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<shuffle>
action: /say Shuffling collections in shell: http://mywiki.wooledge.org/BashFAQ/026 Avoiding bias: http://blog.codinghorror.com/the-danger-of-naivete/
created_on: 1420128653
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<sigkill>
action: /say SIGKILL is exactly the same as SIGTERM except that it doesn't invoke the process' signal handlers. You should *never* use it unless you *know* the process is bugging out in its signal handler.
created_on: 1244710721
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<signal>
action: /call trap
created_on: 1355949397
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 20
ref_user: nobody
type: text
<sigs>
action: /say SIGTERM: Tells a process to clean up and stop running. SIGINT: User wants to drop back to his shell. SIGQUIT: User saw a bug and wants you to dump debug info. SIGHUP: User closed his terminal. SIGKILL: User wants you to drop what you're doing and stop immediately.
action: /say Before you boldly claim that some common command doesn't work, try simplifying the command string or script down to the basics to see if the problem still occurs.
created_on: 1344014685
enabled: 1
owner: sjohnson
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<sjohnsonrev>
action: /say # echo "gip taf ma I" | sed 's/ /_/g;s/./&\n/g' | tac | xargs | sed 's/ //g;s/_/ /g'
action: /say # s="gip etuc a ma i" i=-1 IFS=$'\n'; for c in $(sed 's|.|&\n|g' <<< "$s"); do ((i++)); alias "$i"="printf %s \"$c\""; done; unset IFS; for i in $(eval echo {$i..0}); do eval ${BASH_ALIASES[$i]}; done
action: /say Don't skim. Read. There is a lot of information in links we give you, and in man pages. Once you've read it once, and have absorbed the information, feel free to skim for reference. But until you know it, read the whole thing.
created_on: 1311960160
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<sl>
action: /say The reason you don't want . in PATH is because you might be sitting in /tmp and accidentally type "sl" instead of "ls", and voila! You've run the hax0r's /tmp/sl command.
created_on: 1312919494
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<slashes>
action: /say You don't always have to use sed 's/foo/bar/'. If bar contains slashes, you can use a different delimiter, like sed 's#foo#bar#'. Any printable character can be used.
created_on: 1180962026
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<slice>
action: /say Some people use the word "slice" to mean "a contiguous set of array elements", as in "I want array elements 5 through 7". "${array[@]:5:3}" or "${@:5:3}"
created_on: 1294263342
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<slurp>
action: /say To read a file's contents into a variable: var=$(< file) However, this strips trailing newlines. To work around that: var=$(cat file; printf x) var=${var%x} In bash 4.1 and above, read -rN0 < file
created_on: 1426810052
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<smaller>
action: /say When you're trying to find your mistake in a shell script, make the script SMALLER. Smaller is better. Reduce your code to the bare minimum size that still shows the problem. You'll probably end up fixing it yourself in the process.
action: /say Hey, you! Mac user! http://www.iclarified.com/38772/how-to-disable-curly-quotes-in-mac-os-x-mavericks
created_on: 1399645818
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<smiley>
action: /say m# case { { ( { ) ( <<< :-\) cat ) }
created_on: 1378595696
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<so>
action: /call stackoverflow
created_on: 1415046755
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<so_html>
action: /say http://stackoverflow.com/questions/1732348/#1732454 (best response to parsing HTML with regex yet)
created_on: 1326775529
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<solution>
action: /say "The first part of solving any problem is making sure you understand what you are trying to solve. If you can't cogently and clearly state what you are trying to do, then how can you expect anyone else to understand what you are trying to do?"
action: /say sort(1) is an external command that sorts your input lexicographically or numerically. See http://to.lhunath.com/bashlib#L1207 for a bash sorter that can optionally take a comparator command.
action: /say To sort(1) on the second field: -k 2,2
created_on: 1366333774
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<sortfiles>
action: /say declare -a files; n=0; while IFS= read -r -d ''; do for((i=0;i<=n;i++)); do if [[ "$REPLY" -nt "${files[i]}" ]]; then for((j=n;j>i;j--)); do files[j]="${files[j-1]}"; done; files[i]="$REPLY"; ((n++)); break; fi; done; done < <(find . -type f -print0) # sorts all files under . in descending order by mtime; requires a find(1) that supports -print0
created_on: 1364405722
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 31
ref_user: nobody
type: text
<source>
action: /say ''. <script>'' (or "source", which is not portable) reads and executes the commands from <script> in the current shell.
created_on: 1408097715
enabled: 1
owner: cdown
rate_limit: 10
ref_count: 184
ref_user: nobody
type: text
<sp>
action: /say Special Parameters (magic read-only builtin "variables"): http://www.gnu.org/software/bash/manual/bashref.html#Special-Parameters
created_on: 1293135409
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<space>
action: /say In bash, whitespace is syntax. You can't be lax with it: var=value; [[ "$var" = "$value" ]]
created_on: 1393340605
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<spaces>
action: /say Spaces in bash are important syntax: they separate command names and arguments. foo = bar is NOT AN ASSIGNMENT (runs foo with arguments = and bar), if [-d "$dir"] is NOT A TEST (runs the program [-d). Also remember to quote ALL your expansions to avoid unintentionally syntactical spaces from your data: rm "$file" (NOT rm $file).
created_on: 1373045575
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 26
ref_user: nobody
type: text
<spaceship>
action: /say "Can you please help me build a space ship? I have only one variable, a, and its value is 0"
created_on: 1302048246
enabled: 1
owner: gau13
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<spam>
action: /say Please don't make us do this: while : ; do wget -O/dev/null -o/dev/null http://www.<yourSpammyDomain>.com/ ; done
created_on: 1196629785
enabled: 1
owner: igli
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<special>
action: /say Special Parameters are read-only pseudo-variables, such as $$ (PID), $! (bg child PID), etc. See http://mywiki.wooledge.org/BashGuide/Parameters
created_on: 1269540659
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<specialchars>
action: /say Inside single quotes there are no special characters (but you can't put a single quote *inside* a single-quoted string); inside double quotes, \ and $ are special; outside quotes, \ and $ & ( ) | ; < > * ? [ ] are special along with whitespace, and in certain contexts # = ~ { } are also special.
created_on: 1391981657
enabled: 1
owner: kurahaupo
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<speed>
action: /say If speed or performance is an issue, try ##c
action: /say sponge() ( tmp=$(mktemp) && cat > "$tmp" && cat -- "$tmp" > "$1" && rm -- "$tmp"; ) # read and write the same file in a pipeline: grep -v '^#' file | sponge file
created_on: 1414084570
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<spoon>
action: /say We're not here to spoon-feed you, nor are we your private tutor. Try stuff out after reading the urls, and then ask, pasting a cmd into irc, followed by the error msg.
created_on: 1203972777
enabled: 1
owner: igli
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<sprintf>
action: /say Instead of capturing the output of printf, bash's printf can be assigned directly to a variable. printf -v myvarname %04d "$i"
action: /say openssh's "forced command" receives an SSH_ORIGINAL_COMMAND set to the command passed to "ssh". forced-commands SHOULD NOT try to parse shell code from it. Use it only for entirely custom protocols (akin to internal-sftp) or a non-restrictive wrapper.
created_on: 1417028923
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<sshcleanup>
action: /say Cleaning up your remote ssh command: http://stackoverflow.com/questions/3413432
created_on: 1281599200
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<sshconfig>
action: /say openssh configuration files (man ssh_config). Also, see http://cyber.com.au/~twb/.ssh/config.
action: /say You can duplicate an entire directory hierarchy onto a remote host using ssh and pax: cd /source && pax -w . | ssh me@remotebox 'cd /target && pax -r'
created_on: 1391504878
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<sshtar>
action: /say You can duplicate an entire directory hierarchy onto a remote host using ssh and tar: cd /source && tar cf - . | ssh me@remotebox 'cd /target && tar xf -'
created_on: 1314125369
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 10
ref_user: nobody
type: text
<stack>
action: /say The FUNCNAME array variable contains the names of all the functions in the current function-call stack.
action: /say Like virtually every other web site you find via Google, StackOverflow is chock full of wrong answers. Verify everything you read there before using it.
action: /say is a tool some systems have to display metadata on files and file systems. It is NOT recommended for use in scripts since there are no guarantees that systems have stat(1) and even less guarantees that the options of your stat will in any way resemble the options of another's. For file size, use wc, for time checks use test.
action: /say Standard Error is the secondary file descriptor to which commands print to the terminal. It's meant for messages that shouldn't be parsed by default. Redirect to stderr: '>&2'. See !stdout !stdin and !redirtut for more info.
created_on: 1241488303
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<stdin>
action: /say Standard Input is the file descriptor from which commands can read input. See !stdout !stderr and !redirtut for more info.
created_on: 1238419650
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 30
ref_user: nobody
type: text
<stdout>
action: /say Standard Output is the primary file descriptor to which commands print to the terminal. See !stderr !stdin and !redirtut for more info.
created_on: 1238419541
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<step>
action: /say To step through your code, look into bashdb or put this where you want to begin stepping: trap '(read -p "[$BASH_SOURCE:$LINENO] $BASH_COMMAND?")' DEBUG
created_on: 1299489763
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<stfw>
action: /say Search The Fucking Web
created_on: 1162494677
enabled: 1
owner: smg
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<sth>
action: /say Stop being a lazy git, and/or learn to spell. http://mywiki.wooledge.org/NetEtiquette
created_on: 1297186164
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<sticky>
action: /say The "sticky" bit (octal permission bit 01000) on a directory prevents removing other people's files. See http://mywiki.wooledge.org/Permissions#sticky
created_on: 1309196837
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<stopclever>
action: /say “UNIX tools were not designed to stop users from doing stupid things, as that would also stop them from doing clever things.” — Doug Gwyn
created_on: 1415918849
enabled: 1
owner: fr33loader
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<strace>
action: /say strace(1) is a linux tool for viewing the system calls applications make. It is invaluable for debugging more complex or stubburn problems. On certain other systems, dtruss(1) might achieve the same thing. To use it, just put strace/dtruss in front of your command.
created_on: 1224278403
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<stream>
action: /say Programs designed to be used on a stream of data include sed and grep.
action: /say Some assorted coding guides, ideas welcome: http://bash-hackers.org/wiki/doku.php/scripting/style google style: https://google-styleguide.googlecode.com/svn/trunk/shell.xml
created_on: 1411991608
enabled: 1
owner: pgas
rate_limit: 10
ref_count: 44
ref_user: nobody
type: text
<su>
action: /say "Switch user". This command either gives you an interactive shell as a different UID, or it allows you to execute a specified command as a different UID. You *do* have to tell it what command you want to run with the other UID, if you're trying to use it in a script. And you MUST give the username! su root -c '/foo/bar baz quux'
action: /say sudoedit is a wrapper around sudo that allows editing of files not owned by you, which does proper file locking etc. You should use it for editing files in /etc. Equivalent to sudo -e.
created_on: 1384770857
enabled: 1
owner: mattcen
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<sudoers>
action: /say username ALL = NOPASSWD: /some/program
created_on: 1178655651
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 18
ref_user: nobody
type: text
<sudofail>
action: /say sudo echo > file -- bash operations such as redirections, glob expansions, etc. are performed by the USER's bash, not by sudo. Consider: `sudo tee file` or `sudo bash -c 'echo > file'`
created_on: 1393259517
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<sudotalk>
action: /say Sudo: You're Doing it Wrong: https://www.youtube.com/watch?v=o0purspHg-o
created_on: 1434819454
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<suid>
action: /say The SUID bit doesn't work on interpretted scripts in Linux. Use sudo or http://pastebin.com/f1967215f: wget -O code.c 'http://pastebin.com/pastebin.php?dl=f1967215f' ; nano code.c ; gcc -o run code.c ; sudo chown root run ; sudo chmod 4755 run
created_on: 1250278984
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 12
ref_user: nobody
type: text
<sum>
action: /say sum the values of the first column: awk '{tot += $1} END {print tot}'
created_on: 1353519279
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 18
ref_user: nobody
type: text
<supercopy>
action: /say supercopy(){ sudo sh -c 'for file in "${@:2}"; do cp "$file" "$1" && chown "$SUDO_UID":"$SUDO_GID" "$1"/"${file##*/}"; done' _ "$@"; } # usage: supercopy destination files [...]; copies all files to destination and changes the copies' ownership to the uid/gid of the invoking user
created_on: 1369984926
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<surgeon>
action: /say <mcantor> I feel like a surgeon who opened up a patient for a hernia procedure only to find that the liver is atrophied, a lung is collapsed and the kidneys have simply been replaced with a Post-It note saying "Sorry"
created_on: 1304524669
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<suspense>
action: /say The suspense is killing us.. do tell ;-) If you figured out a problem you asked us about, it's only polite to share the solution as well as the work. That way other people who didn't know the answer gain something from your time with us. :)
created_on: 1197698024
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<svercmp>
action: /say Simple version comparison in pure bash: https://github.com/dualbus/myscripts/blob/master/svercmp
created_on: 1383924361
enabled: 1
owner: dualbus
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<svg>
action: /say Scalable Vector Graphics, an XML-based vector image format. If someone's got svg questions, they should probably ask me about <xml>.
created_on: 1383077835
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<svn>
action: /say If you're considering removing .svn directories, first read "svn --help export". If you're not convinced, find . -name .svn -prune -exec rm -rf {} +
action: /say Programs designed to be used on tabular data include awk, cut, and paste.
created_on: 1188812765
enabled: 1
owner: ivazquez
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<tac>
action: /say tac(1) is a non-standard GNU-only command. A POSIX equivalent would be awk '{a[i++]=$0} END {while (i--) print a[i]}'
created_on: 1302830131
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<tar>
action: /say tar is an archiver but not the only one. Usually tar is a good choice (e.g. to duplicate an ENTIRE file system), but if you need fine-grained control, find|cpio or find|pax wins
created_on: 1333544479
enabled: 1
owner: Bronze
rate_limit: 10
ref_count: 26
ref_user: nobody
type: text
<tcl>
action: /say No, seriously, you can actually use Tcl for *other things* besides expect!
action: /say Part of ucspi-tcp <http://cr.yp.to/ucspi-tcp.html>, useful for providing easy, robust network services WITHOUT having to be superuser or edit a monolithic inetd.conf file.
action: /say tee reads from standard input and writes to standard output *and* one or more files
created_on: 1278616057
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 75
ref_user: nobody
type: text
<telnet>
action: /say "A perfectly good tool for diagnosing issues with SMTP and HTTP servers." -greycat Otherwise, not a secure way to connect to a shell for administrative purposes.
action: /say a hardware device used for user input/output in the early Cretaceous period of computing. Consisted of a primitive TV-like tube which "drew" characters on the screen in fixed positions. Most early terminals were limited to 24 lines high by 80 chars wide. At the time this was considered a miracle of technology.
action: /say Testing is for *you*. PLAY with the code, work out what it means; short snippets show the idea. /msg greybot tias ;-)
created_on: 1205125691
enabled: 1
owner: igli
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<tests>
action: /say Use [[ .. ]] for testing strings or files, (( .. )) for testing numbers and 'if ..'' for testing commands. Do *NOT* use [ .. ] in bash (only in sh). See <http://mywiki.wooledge.org/BashSheet#Tests> and <http://mywiki.wooledge.org/tests>. Difference between [ and [[: <http://mywiki.wooledge.org/BashFAQ/031>
action: /say Give us a sample input line, and tell us what you want the output to be.
created_on: 1182554021
enabled: 1
owner: igli
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<thanks>
action: /say Don't thank me, I'm a bot. Did you mean to thank greycat?
created_on: 1193321813
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 40
ref_user: nobody
type: text
<thebasics>
action: /say People in #bash are here to help others work through problems and chellenges and direct people in learning. This isn't a 101 classroom, though. If you don't know the basics, read the guide.
created_on: 1414876006
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<theory>
action: /say The difference between theory and practice? In theory there is no difference. In practice there is.
created_on: 1391536453
enabled: 1
owner: emg
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<thequestion>
action: /say [[ $question =~ (bb|[^b]{2}) ]]
created_on: 1195287345
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<thompson>
action: /say The Thompson shell was the predecessor to the Bourne (q.v.) shell, used in versions of Unix prior to 7th edition. A modern port of the Thompson shell is available at http://v6shell.org/ .
action: /say THX? That digital audio thing they use in movies? Oh, wait, you want http://yaku.dk/s/irc/dont-use-thx-sry-plz.txt or section 1.1 of http://mywiki.wooledge.org/NetEtiquette
action: /say Try It And See, But Don't Try rm -rf / As Root
created_on: 1171815120
enabled: 1
owner: VImtermute
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<tib>
action: /say Try it before you buy it! Make small one liners on the command line to make sure you understand what and how you are using an idea before you stick it the middle of a complex script.
created_on: 1198683370
enabled: 1
owner: savetheWorld
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<time>
action: /say ''time'' is a bash builtin, see ''help time''. There may also be a time command installed on the system, documented in ''man time'' -- see !faq 86 to bypass bash's builtin time command, or !faq 32 to redirect the output of the builtin to a file.
action: /say http://mywiki.wooledge.org/BashFAQ/068 -- How do I run a command, and have it abort (timeout) after N seconds?
created_on: 1361395078
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 52
ref_user: nobody
type: text
<timestamp>
action: /say exec > >(trap : 1 2 3 15 ; while IFS= read -r x ; do printf '%(%F%T)T %s\n' -1 "$x" ; done >>/var/log/mylog) 2>&1 # requires bash4.2 or later
created_on: 1433929182
enabled: 1
owner: llua
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<timingpe>
action: /say val=$'foo\n'; { time for ((i=0;i<2000;++i)) ; do echo "${val%$'\n'}" ; done >/dev/null; } 2> >(tr '\n\t' ' ')
created_on: 1261368495
enabled: 1
owner: tuxdev_
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<timingpipe>
action: /say val=$'foo\n'; { time for ((i=0;i<50;++i)) ; do echo "$val" | tr -d '\n'; done >/dev/null; } 2> >(tr '\n\t' ' ')
created_on: 1261368366
enabled: 1
owner: tuxdev_
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<timtowtdi>
action: /say There Is More Than One Way To Do It
created_on: 1217967692
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<timtowtdiamotwaw>
action: /say There is More Than One Way To Do It And Most Of Those Ways Are Wrong
created_on: 1260819539
enabled: 1
owner: tuxdev
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<tiocsti>
action: /say The TIOCSTI ioctl() command lets you insert input into a terminal driver's queue. "Simulate Terminal Input".
created_on: 1259182705
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 14
ref_user: nobody
type: text
<title>
action: /say You can change xterm titles with something like: printf '\e]2;%s\a' "title goes here"
created_on: 1251590569
enabled: 1
owner: ferret
rate_limit: 10
ref_count: 16
ref_user: nobody
type: text
<tlcl>
action: /say The Linux Command Line (book by William Shotts). A good guide to the command line in general, but not a fantastic example for good Bash practices: http://www.linuxcommand.org/tlcl.php and http://sourceforge.net/projects/linuxcommand/files/TLCL/13.07/TLCL-13.07.pdf/download
created_on: 1399646410
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<tldp>
action: /say the tldp bash guide is outdated, and in some cases just plain wrong. There's a reason it isn't in the topic.
action: /say FAQ: http://mywiki.wooledge.org/BashFAQ | Guide: http://mywiki.wooledge.org/BashGuide | ref: http://xrl.us/bhk9ww | http://wiki.bash-hackers.org/ | USE MORE QUOTES!: http://www.grymoire.com/Unix/Quote.html | Scripts and more: http://www.shelldorado.com/ | New official help mailing list: http://tx0.org/31f
action: /say Comparison of popular transfer protocols: http://winscp.net/eng/docs/protocols#protocol_comparison
created_on: 1248138746
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<tpgrp>
action: /say every process has a PID, a process group (PGRP, which is its own PID, or the PGRP inherited ftom its parent), and a session (SID). All processses in a PGRP have the same SID. A terminal has a session & a foreground process group (which must be in the same SID). If the terminal's SID changes, all the processes with that SID get SIGHUP. If you type ctrl-C or ctrl-Z then the PGRP gets SIGINT or SIGTSTP
created_on: 1390561568
enabled: 1
owner: kurahaupo_mobile
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<tput>
action: /say Do NOT hardcode terminal escape sequences. Use tput with the sequence names from man terminfo to get the right code for your terminal. Eg. red=$(tput setaf 1); echo "Hello ${red}world!" # Variables example: http://to.lhunath.com/bashlib#L210 more info at http://www.gnu.org/software/termutils/
created_on: 1427210577
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<trap>
action: /say http://mywiki.wooledge.org/SignalTrap ## To clean up on exit, don't trap a bunch of signals. Instead, trap cleanupFunc EXIT
action: /say trim whitespace, like SQL TRIM() -- For shell variables: «shopt -s extglob; x=${x##+([[:space:]])} x=${x%%+([[:space:]])}». For streams: «cmd | sed 's/^[[:space:]]*//; s/[[:space:]]*$//'». See: http://mywiki.wooledge.org/BashFAQ/067
action: /say The Standard Associative Array Problem: "I have two files, one of which defines keys and values, and I want to iterate through the second file and replace all the keys with their values."
created_on: 1305231088
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<tshirt>
action: /say "You were treated harshly in #bash? well, it happens. Here's your T-shirt. It says: Been there, had that done to me."
action: /say "tty" originally stood for teletype, a primitive keyboard+printer which was the forerunner of the ASCII terminal. Nowadays it is used generically to mean "some kind of terminal", usually a pseudoterminal (X terminal emulator, Linux console, etc.). http://www.linusakesson.net/programming/tty/
action: /say A list of tutorials can be found here: http://wiki.bash-hackers.org/scripting/tutoriallist
created_on: 1309530239
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 27
ref_user: nobody
type: text
<tutorials>
action: /call tutorial
created_on: 1335733502
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 38
ref_user: nobody
type: text
<ty>
action: /call plz
created_on: 1298917351
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<type>
action: /say type tells you how a command will be interpreted by the shell. Don't use 'which'; use 'type' instead, because it's portable and consistent.
created_on: 1374326817
enabled: 1
owner: geirha
rate_limit: 10
ref_count: 40
ref_user: nobody
type: text
<type-foo>
action: /say When someone tells you to do "type foo", that means 1) put your hands on the keyboard 2)key-in "type foo", without the quotes :-)
created_on: 1389062850
enabled: 1
owner: Jetchisel
rate_limit: 10
ref_count: 9
ref_user: nobody
type: text
<typeset>
action: /say Set variable values and attributes. Obsolete. See '!declare'.
action: /say Universal Greeting Time http://thinkmoult.com/ugt.html
created_on: 1394730934
enabled: 1
owner: emg
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<ulimit>
action: /say ulimit is bash's interface to the setrlimit()/getrlimit() system calls. Resource limits are inherited by child processes, just like environment vars.
action: /say Use more quotes, not just when assigning variables. Try these examples: WRONG: Var="/* is two punctuation marks" && echo $Var ; RIGHT: Var="/* is two punctuation marks" && echo "$Var"
created_on: 1303163441
enabled: 1
owner: kwtm
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<unary>
action: /say "unary operator expected" typically means you forgot to quote something. [ $foo = bar ] is wrong. [ "$foo" = bar ] is OK.
created_on: 1317754790
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<unbuffer>
action: /say stdbuf runs commands with modified buffering operations. man stdbuf(1)
created_on: 1355277061
enabled: 1
owner: juanmabc
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<uncolour>
action: /say uncolour() { sed -e $'s/\e[[][\\0-\\077]*m//g'; }
created_on: 1292163877
enabled: 1
owner: ferret
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<undefine>
action: /call unset
created_on: 1314631794
enabled: 1
owner: HawkI
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<understand>
action: /say Those who do not understand UNIX are condemned to reinvent it, poorly. --Henry Spencer
created_on: 1249669278
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<unicode>
action: /say Dealing with characters correctly is harder than you might think. eg. a-z does NOT mean "all lowercase letters". http://stackoverflow.com/a/6163129/58803 (skip down to "Assume Brokenness") is an *excellent* introduction to these misunderstandings.
created_on: 1344015874
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<uniq>
action: /say is a utility for removing or reporting repeated lines. uniq will only work for showing unique lines when used with sorted input (sort | uniq). Alternatively, use sort -u. awk '!s[$0]++' is an order-insensitive alternative.
created_on: 1398726929
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 62
ref_user: nobody
type: text
<uniqarray>
action: /say # typeset -a a=(a b c c d d d e f '' '' _ _); o=$(typeset -p a); typeset -A vals; for key in "${!a[@]}"; do ((vals[_${a[key]}]++)) && unset -v 'a[key]'; done; printf 'before: %s\nafter: %s\n' "$o" "$(typeset -p a)"
created_on: 1395680824
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<unix>
action: /say You should be fully aware that when people say Unix they do not necessarily mean "The copyrighted proprietary operating system currently owned by AT&T or Novell or SCO or Cisco or whoever the fuck owns the copyright at this particular instant of time", but rather the whole FUCKING SPECTRUM OF UNIX-LIKE OSES including AIX, HP-UX, Linux, BSD, Solaris, etc.
action: /say Unquoted $@ and $* give unspecified behavior (as far as we can tell). Always quote them. A partial list of various unquoted behaviors by shell is here: http://wiki.bash-hackers.org/syntax/pe#bugs_and_portability_considerations
created_on: 1357712918
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<unset>
action: /say Unset undefines a variable or function from the current shell process. See: http://wiki.bash-hackers.org/commands/builtin/unset http://fvue.nl/wiki/Bash:_Unset. Testing if a variable is set: [[ ${var+_} ]]. See !isset
action: /say If you're asking "How can I find all the files that have been uploaded recently?" then you're probably in deep trouble. The server side can't tell when a file is finished uploading unless the client renames it or uploads an "all done" file afterward.
created_on: 1237220725
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<upstart>
action: /say Ubuntu doesn't use System V init like you probably expected. It uses "upstart" instead. See http://upstart.ubuntu.com/ or ask in #ubuntu.
created_on: 1315587970
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<upvar>
action: /say see: http://fvue.nl/wiki/Bash:_Passing_variables_by_reference also: http://wiki.bash-hackers.org/commands/builtin/unset#scope and http://wiki.bash-hackers.org/syntax/arrays#indirection and http://mywiki.wooledge.org/BashFAQ/006#Assigning_indirect.2BAC8-reference_variables
created_on: 1355930418
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<uri>
action: /say pout(){ local field; for field in "${line[@]}"; do [[ $field =~ $re ]] && echo "$field"; done;}; uri_search(){ local LC_ALL=C re='^[A-Za-z][A-Za-z0-9+-\.]*://' file=; local -a line; for file; do while read -r -a line; do pout; done < "$file"; [[ "${line[@]}" ]] && pout; done;} # Usage: uri_search file ...; prints absolute URIs contained in given files
action: /say Prepare literal data for injection into a URL path component or GET attribute: urlquote() { local c; while IFS= read -rd '' -n1 c; do printf '%%%02x' "'$c"; done <<< "$1"; }; curl "http://www.google.com/search?q=$(urlquote "$query")"
created_on: 1340009907
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 28
ref_user: nobody
type: text
<us-intl>
action: /say If you are using a Linux desktop, and want to type symbols such as «french-quotes» “double-quote” and ‘single-quotes’, then set your keyboard type to "US International", and then use AltGr with [ ] { } 9 0 respectively
created_on: 1383887866
enabled: 1
owner: kurahaupo
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<useawk>
action: /say Stuff with lines? Use awk. ;)
created_on: 1181927970
enabled: 1
owner: VImtermute
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<usecase>
action: /say What is the *REAL* (non-technical) problem or issue you are trying to address? Describe it clearly and concisely using little or no technical terminology, command names, etc. A concise explanation of *WHY* you are doing what you are doing is equally helpful.
created_on: 1363893033
enabled: 1
owner: fr33loader
rate_limit: 10
ref_count: 52
ref_user: nobody
type: text
<users>
action: /say http://wooledge.org/mywiki/BashFaq -- Why don't users ever read the FAQ themselves? Why do I always have to grep the whole file for their questions? Huh? Doesn't anyone ever think of the bot?
created_on: 1170963902
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<using>
action: /say "How can I do X using Y?" NEVER ask a question of that form. Y may not be the best way to do X. All you should ask is, "How do I do X?"
action: /say Unnecessary use of echo -- "echo foo | bar" uses a pipe, which generates an implicit subshell, which changes the variable scope. Pipes are also expensive. Use a here string instead: "bar <<< foo". See http://wooledge.org:8000/BashPitfalls
created_on: 1232569364
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 26
ref_user: nobody
type: text
<uuog>
action: /say useless use of greybot
created_on: 1336481605
enabled: 1
owner: juanmabc
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<uuok>
action: /say Unsafe Use of Kill: kill -9 sends SIGKILL to a process which is the exact same thing as normal kill (SIGTERM), except that it prevents the process from cleaning up after itself. You do NOT want to use it. See http://partmaps.org/era/unix/award.html#uuk9letter
action: /say What you said is so much better than what I said and I defer to your wisdom.
created_on: 1301169674
enabled: 1
owner: kwtm
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<v7>
action: /say Seventh Edition Unix (V7, 1979), introduced the Bourne shell, which replaced the earlier Thompson shell. If your script needs to work on pre-POSIX Unix systems, V7 is a good portability target. A full tree of V7, including source and man pages, may be found at http://minnie.tuhs.org/UnixTree/V7/ .
created_on: 1208465676
enabled: 1
owner: \amethyst
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<vaccuumdb>
action: /say VACCUUM
created_on: 1221004577
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<vagueness>
action: /say VAGUENESS CAUSES HEART DISEASE!
created_on: 1151075489
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<varcap>
action: /say By convention, environment variables (PATH, EDITOR, SHELL, ...) and internal shell variables (BASH_VERSION, RANDOM, ...) are fully capitalized. All other variable names should be lowercase. Since variable names are case-sensitive, this convention avoids accidentally overriding environmental and internal variables.
action: /say 1. Do NOT put commands or variable names INSIDE variables; use a function or write it out in your script. 2. Do NOT put multiple filenames inside a string; use arrays. 3. Remember to quote every expansion of your variables to protect their data.
created_on: 1214572768
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<variables>
action: /say to see all your shell variables, type set
created_on: 1279035594
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 44
ref_user: nobody
type: text
<vars>
action: /say There are two types of variables. Most variables in bash are Shell Variables (foo=bar). They exist only in the running shell and are inherited by subshells. Environment Variables (export foo=bar) are variables that exist in every process. They are NOT global, every child gets a fresh copy of the parent's whole environment. http://mywiki.wooledge.org/Environment
created_on: 1391135139
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<vi>
action: /say Vi is an editor. Use it in scripts like this: vi -c 's/foo/bar/|x' file -- See http://www.opengroup.org/onlinepubs/009695399/utilities/vi.html
action: /say read and memorize the terms/names used on the bash man page. When you use the bash names for things correctly you'll get 800% better results in #bash, and reduce our work correspondingly!
created_on: 1300131323
enabled: 1
owner: HawkI
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<vt100>
action: /say ANSI X3.64 is a terminal control code standard supported by most modern terminals. VT100 is a subset implemented by DEC's VT100/102. DO NOT hardcode codes, use tput(1) instead (eg. red=$(tput setaf 1)). Many different terminals use slightly different codes, tput finds the right code for the job. http://unix.stackexchange.com/a/5802 http://wiki.bash-hackers.org/scripting/terminalcodes
action: /say By default, wait waits for all of your shell's children to exit. If arguments are specified, wait waits for the specified job ids to exit. # http://mywiki.wooledge.org/ProcessManagement
action: /say to help understand how watch(1) handles quotes/parsing, think of it as running this: watch() { sh -c "$*"; while sleep 2; do sh -c "$*'; done; }
created_on: 1345490563
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<wayrttd>
action: /say What are you /REALLY/ trying to do!?
created_on: 1356324690
enabled: 1
owner: mattcen
rate_limit: 10
ref_count: 192
ref_user: nobody
type: text
<wayttd>
action: /say What Are You Trying To Do?
created_on: 1216437933
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<wc>
action: /say wc(1) is a command that counts words, or lines, or characters in files. If you redirect the file as stdin, it doesn't print the name. Very useful. Example: if (( $(wc -l < "$file") > 10 )); then ...
created_on: 1180124419
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<wc-c>
action: /say A portable method of finding a file's byte-size is: read size _ < <(wc -c file); or the "hack": size=($(wc -c file))
action: /say We don't care what your name is... we don't care where you live... we don't care how old you are. Ask your question or leave.
created_on: 1186131946
enabled: 1
owner: ivazquez
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<wfm>
action: /say Works For Me!
created_on: 1269369778
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 17
ref_user: nobody
type: text
<wget>
action: /say wget has a man page. Hint: this channel is not it.
created_on: 1185375966
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<what>
action: /say Tell us WHAT you want to do, not HOW you're trying to do it.
created_on: 1211398620
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<which>
action: /say which(1) is an external program used to search PATH for an executable. It behaves differently on different systems and you can't rely on a useful exit code; use (from most to least portable) ''command -v'' or ''type -P'' (to find the path) or ''hash'' (to check) instead. See http://mywiki.wooledge.org/BashFAQ/081
action: /say To iterate over find results safely: while IFS= read -r -d '' file; do ...your code...; done < <(find ...your predicates... -print0)
created_on: 1393469840
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<whileread>
action: /say A while loop that reads line-by-line: while IFS= read -r line; do something "$line"; done
created_on: 1400634038
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 23
ref_user: nobody
type: text
<whine>
action: /say why do channel helpers have to whine whenever someone asks a question? Maybe he doesn't know his answer is in the parameter expansion secion of some 100k line faq or man page. Stop wasting everyone's bandwidth and type /exit if people asking for help bothers you so much.
created_on: 1180832485
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<whinge>
action: /say "With Free Software you either do, or you wait." whinging doesn't work, and leads to being ignored ;)
created_on: 1187666751
enabled: 1
owner: igli
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<whitespace>
action: /say Sometimes whitespace is necessary, eg after [ and [[ and before ] and ]]. Othertimes it breaks stuff eg in {1..9}
created_on: 1238352919
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 20
ref_user: nobody
type: text
<whoami>
action: /say whoami is not a standard command, use the more portable "id -un" instead. bash offers UID and EUID, and your system the LOGNAME environment variable.
created_on: 1394900483
enabled: 1
owner: Riviera
rate_limit: 10
ref_count: 3
ref_user: nobody
type: text
<why>
action: /say Trying to solve a problem without first understanding why it happens or what you really want will always yield you a broken result. Explain the WHY to us (or to yourself) in detail first.
created_on: 1290783080
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<whynot>
action: /say You can THINK whatever you want, and then when you're done fantasizing, you can read the documentation that tells you what actually does work.
created_on: 1186172112
enabled: 1
owner: igli
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<whynotls>
action: /say as ls -F, ls -q, -> on symlinks, date and time formats varying between locales, date and time formats depending on the age of the file in the POSIX locale, spaces in the user name, spaces in the group name, spaces in the filename, newlines in the filename (more or less unfixable), groups might not even be displayed, probably more....
action: /say "When there's a will, there's a way..."
created_on: 1379661264
enabled: 1
owner: sjohnson
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<window_scaling>
action: /say Users of Linux 2.6.8+ kernels, beware! I live on a part of the Internet behind a router with the TCP window scaling bug, and Linux 2.6.8+ makes it impossible to reach me. Read <http://lwn.net/Articles/92727/> for details and workaround.
created_on: 1151427747
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<wiyug>
action: /say What is your *ultimate* goal? Think *big* without telling us how you want the goal achieved.
created_on: 1356744905
enabled: 1
owner: fr33load3r
rate_limit: 10
ref_count: 14
ref_user: nobody
type: text
<words>
action: /say Some words about words: http://wiki.bash-hackers.org/syntax/words and http://mywiki.wooledge.org/WordSplitting
created_on: 1362528598
enabled: 1
owner: BlastHardcheese
rate_limit: 10
ref_count: 54
ref_user: nobody
type: text
<wordsplitting>
action: /say echo $foo; rm $foo -- If you leave $foo unquoted, bash will *remove* all whitespace (newlines, spaces, tabs) while expanding it, take each *word* as a separate argument. `echo` prints these words separated by one space and `rm` deletes each word. So ALWAYS *quote* your parameter expansions: echo "$foo"
created_on: 1242638629
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 208
ref_user: nobody
type: text
<work>
action: /say In this context, the word "work" is misleading. We're here looking for solutions, not hacks. Be specific about what you need, and try to let go of how you think it should be done.
created_on: 1257341884
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 8
ref_user: nobody
type: text
<workaround>
action: /say Don't work around the problem. Fix the problem. Or you'll end up with more problems.
created_on: 1278788339
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<works>
action: /say You might think some suggestions appear superfluous, but we aren't making this stuff up. It's risky to parse ls, top and ps, and quotes are important. You care about your script more than we do, so try to understand why we made the suggestion instead of just repeating what seems to work to you.
created_on: 1185902540
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<worship>
action: /say We all worship POSIX and never question POSIX
action: /say Repeat $str $n times # for ((i=1;i<=n;i++)); do printf %s "$str"; done # printf -v tmp %${n}s ''; echo "${tmp// /$str}" # eval printf "'%.0s$str'" {1..$n} # Be sure $str is safe for whatever your code does with it!
created_on: 1257959323
enabled: 1
noembed: 1
owner: greycat
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<x++>
action: /say postincrement and postdecrement alter the variable but yield the value from BEFORE the modification
created_on: 1410300845
enabled: 1
noembed: 1
owner: kurahaupo
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<x11>
action: /say In order for programs to do something involving X11, the program needs to know which X11 to connect with and how to connect with it. This is usually done by setting the DISPLAY environment variable, eg DISPLAY=:0 command
created_on: 1391908488
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<xargs>
action: /say xargs(1) is dangerous (broken, exploitable, etc.) when reading non-NUL-delimited input. If you're working with filenames, use find's -exec [command] {} + instead. If you can get NUL-delimited output, use xargs -0. Otherwise, you probably want a while read or for loop instead.
created_on: 1421865307
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 397
ref_user: nobody
type: text
<xargsbug>
action: /say # touch "I don't want to miss a thing.mp3"; find * | xargs -n1 rm # By default, xargs(1) breaks on whitespace (making it rm "I" instead of the song) and quotes (the ' in don't).
created_on: 1258636105
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 5
ref_user: nobody
type: text
<xclient>
action: /say In order to run an X client program from outside an X session, you need two things: a valid DISPLAY variable (export it in your script), and a means of authenticating to the X server. The latter can often be done with "export XAUTHORITY=~whomever/.Xauthority". The former requires witchcraft.
created_on: 1239387433
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<xclip>
action: /say is a tool to manipulate the X11 clipboard. xclip -o to print the clip and -i to set it. Not bash.
action: /say Read some assorted debugging tips: http://bash-hackers.org/wiki/doku.php/scripting/debuggingtips
created_on: 1253165227
enabled: 1
owner: TheBonsai
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<xmb>
action: /say special
created_on: 1285183061
enabled: 1
owner: kojiro
rate_limit: 10
ref_count: 10
ref_user: nobody
type: text
<xml>
action: /say You can't parse structured languages like HTML or XML using bash, grep, sed, cut, etc. Look into xmllint, xmlstarlet, xpath, xsltproc, ... Eg. xmllint --xpath '//person[@name="bob"]/salary/text()' - <<< '<staff><person name="bob"><salary>70000</salary></person></staff>' -- Ask #xml for XPath/XSLT help, that is not a #bash question.
created_on: 1382018931
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 323
ref_user: nobody
type: text
<xmlget>
action: /say Retrieve an XML value: xmlstarlet sel -t -v 'staff/person[@name="bob"]' <<< '<staff><person name="bob">70000</person></staff>'
created_on: 1415811082
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 11
ref_user: nobody
type: text
<xmlset>
action: /say Update an XML value: xmlstarlet ed -P --update 'staff/person[@name="bob"]' -v 80000 <<< '<staff><person name="bob">70000</person></staff>' # use -L to update a file in-place.
created_on: 1415811251
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<xterm>
action: /say xterm is an X client program which implements a terminal emulator. It mostly mimics the VT102, with some extensions. Some vendors even added color, so "xterm" as a terminfo label is extremely ambiguous. To set the xterm title bar: settitle() { printf '\e]2;%s\a' "$1"; }
created_on: 1305819860
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 7
ref_user: nobody
type: text
<xtracefd>
action: /say In bash 4.x, the shell variable BASH_XTRACEFD allows you to specify a different file descriptor for xtrace (set -x) output. This can be useful when you want to redirect it elsewhere, without affecting the rest of stderr.
created_on: 1309542286
enabled: 1
owner: e36freak
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<xy>
action: /say http://mywiki.wooledge.org/XyProblem -- "I want to do X, but I'm asking how to do Y..."
action: /say The Y2K excuse: "It is highly unlikely that this program will STILL be in use on Jan 1, 2000."
created_on: 1306271348
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<yes>
action: /say yes endlessly prints 'y' (or whatever argument it is specified with) followed by a newline to stdout. Useful for sending confirmations. e.g. yes | fsck
created_on: 1421709440
enabled: 1
owner: mattcen
rate_limit: 10
ref_count: 4
ref_user: nobody
type: text
<yesdear>
action: /say You appear to have a console issue; what does this command output? echo '16i[q]sa[ln0=aln100%Pln100/snlbx]sbA0D4D465452snlbxq' | dc
created_on: 1186684530
enabled: 1
owner: igli
rate_limit: 10
ref_count: 2
ref_user: nobody
type: text
<ykaya>
action: /say You kids and your acronyms these days!
created_on: 1437763605
enabled: 1
owner: kurahaupo_
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<your>
action: /say It's you're not your - http://i34.tinypic.com/js0mfc.jpg
created_on: 1226141242
enabled: 1
owner: iascorga
rate_limit: 10
ref_count: 0
ref_user: nobody
type: text
<yquotes>
action: /say "At its base, a shell is simply a macro processor that executes commands. The term macro processor means functionality where text and symbols are expanded to create larger expressions." http://tiswww.tis.case.edu/~chet/bash/bashref.html
created_on: 1193220768
enabled: 1
owner: igli
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<yw>
action: /say You're welcome, human.
created_on: 1397113075
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 6
ref_user: nobody
type: text
<zombie>
action: /say A zombie process (also known as a "defunct" process) cannot be killed; it's already dead. A zombie is a process which has exited, but whose parent has not yet waited for it (or wait3()ed for it) to collect its exit status. This often signifies a bug in the parent, unless the time of zombification is brief.
created_on: 1135112196
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 13
ref_user: nobody
type: text
<zsh>
action: /say zsh is NOT an enhanced version of bash. It's a different shell, with different features and there's a different channel for your questions: #zsh For zsh-style completion, bind '\C-i':menu-complete
action: /say Brace and sequence expansion: {a,b,c}1 and {a..c}1 expand to a1 b1 c1, {a..c}{1..3} expands to a1 a2 a3 b1 b2 b3 c1 c2 c3. http://wiki.bash-hackers.org/syntax/expansion/brace http://mywiki.wooledge.org/BraceExpansion http://mywiki.wooledge.org/BashGuide/Patterns#Brace_Expansion
created_on: 1338013686
enabled: 1
owner: ormaaj
rate_limit: 10
ref_count: 152
ref_user: nobody
type: text
<{$>
action: /say {$x..$y} Parameter expansion happens after brace expansion. As a result, your parameters are only expanded after bash has already failed to brace-expand from dollar-x to dollar-y. Instead, use a C-style for: for ((i=x; i<=y; i++))
created_on: 1313790904
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 57
ref_user: nobody
type: text
<{}>
action: /say Command grouping. Like (), but doesn't spawn a subshell. See http://mywiki.wooledge.org/BashGuide/CompoundCommands#Command_grouping
action: /say Pipes are used to send the (standard) output of one process to the (standard) input of another. foo | bar runs a process foo, sends its output on FD 1 to a process bar's input on FD 0. Note that foo and bar are executed in subshells; so changing variables inside pipes will have no effect on the variables in your main script.
created_on: 1224622511
enabled: 1
owner: lhunath
rate_limit: 10
ref_count: 55
ref_user: nobody
type: text
<|&>
action: /say copy/paste from 'man bash': If |& is used, the standard error of command is connected to command2's standard input through the pipe; it is shorthand for 2>&1 |.
created_on: 1343530341
enabled: 1
owner: yitz_
rate_limit: 10
ref_count: 22
ref_user: nobody
type: text
<||>
action: /say Short-circuit control operators <http://mywiki.wooledge.org/BashSheet#Tests> A || B means "Run A. If A fails, run B." A && B means "Run A. If A succeeds, run B." Example: foobar || { echo "error" >&2; exit 1; }
created_on: 1408035667
enabled: 1
owner: greycat
rate_limit: 10
ref_count: 81
ref_user: nobody
type: text
<||&&>
action: /call &&||
created_on: 1424257116
enabled: 1
owner: izabera
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<||:>
action: /say the same thing as "|| true". your script probably also has set -e and || : is a trick to prevent the script from exiting in case the command before the || fails
created_on: 1276606476
enabled: 1
owner: koala_man
rate_limit: 10
ref_count: 1
ref_user: nobody
type: text
<|||>
action: /say When your pipeline gets too long, make sure you can't combine commands into one (grep | awk | awk -> awk, or just use 'read') and try to assign intermediate variables for readability.
action: /say The most basic property is the property that there are no properties; which is a property in itself. The most basic object is the void; which by the same vein of the first sentence means that there cannot be a void. Everything and nothing is filled with something. Existence is simply a paradox of contradictions and opposite reactions. Ones and zeroes, truth and fiction. Everything that shall be will be. A collective imagination of sentience.
created_on: 1258974955
enabled: 1
owner: pragma_
rate_limit: 15
ref_count: 10
ref_user: pragma_
type: text
<fool>
action: /say He who asks a question may be a fool for five minutes; he who does not ask a question remains a fool forever.
action: /say ( y ) is MSN Messenger for the "Thumbs Up" emoticon. It's not an IRC thing. No IRC clients translate it. Pidgin is not an IRC client. It's an instant messenger with a proof-of-concept half-arsed IRC plugin. Knock it off.
action: /say If you have a question, please be specific and concise. Don't ask questions like 'Does anyone know how to ...' or 'What is the best way to ...'. We do not have the time or patience to play a game of 20 questions with people that are not capable of articulating properly. See also: http://catb.org/~esr/faqs/smart-questions.html
action: /say 'A dicto secundum quid ad dictum simpliciter' - the 'Hasty Generalization' logical fallacy, to which new C programmers often fall prey. Fight the urge to let it get you by studying the theory and not trying to learn through testing.
action: "I recommend to" "My advice is to" "I think it $advicehelper2 be $advicehelper3 to" "I think it $advicehelper2 be $advicehelper3 to" "I think it $advicehelper2 be $advicehelper3 to"
action: "There's no easy way to say this. You got aids. Yuck! :x" $noaids "You contracted aids from $who_answers!" "You were attacked by a $animals! You now have aids." $noaids $noaids
action: /say alis is a freenode service that lets you search for channels. See `/msg alis help list` to get started. Examples: `/msg alis list make` to search for all channel names containing "make"; `/msg alis list * -topic make` to search all channels for topic containing "make"
action: Yes. "Most likely." No. "I think not." Brilliant! "Are you a $sizes $idiots?" "Definitely not." "Most assuredly." Absolutely! "Not likely!" "Do I look like I care?" "I'm not sure, let me check." "It would seem so." "I don't think so." "Why are you bothering me with this?" "Forget it!" "Yeah, right." "As if!" "Can has happy fun time!" "But of course." "That gives me an idea!" "Don't be $silly_adjective." "That would be $question_type." Sometimes. "That's $severity $question_type."
action: /say If you have a question, just ask. If somebody knows, they'll answer :) For best results, be specific, informative, complete, concise and on-topic! Don't ask if you can ask a question. Don't ask if anyone uses/knows about foo. Please don't be demanding or insulting. Remember, we're all volunteers. Also see: http://geoff.greer.fm/2012/05/19/programmer-irc-etiquette/
action: a common disease mostly contracted by beginning programmers. There is no known cure except that over time, outbreaks will occur with less and less frequency.
action: tristate: it's the only integral type suffering 3 states: signed, unsigned, and "char". The latter is platform and compiler discretionary. char is the smallest-addressable-unit, and ALWAYS sizeof==1. Are.You.Having.Fun.Yet
action: The New Hacker's Dictionary defines a language lawyer as "a person who will show you the five sentences scattered through a 200-plus-page manual that together imply the answer to your question 'if only you had thought to look there.'"
action: See http://www.cyberspace.org/~pfv/libcgisock.html for a nifty little module for the Apache Web Server that allows a browser to connect to programs already loading and running on remote systems via the ubiquitous Unix-Socket.
action: /say Code::Blocks is a fairly popular IDE for C and C++ development. Some folks beef that it has been distributing nightly builds and not releasing stable ones for quite some time now, others like it for this very fact. http://codeblocks.org
action: /me brews up a $flavor cup of $coffee_type $0 for $args
action_with_args: { return "/me brews up a $flavor cup of $coffee_type $0 for @args" if $args[0] eq "$nick"; return "/me brews up a $flavor cup of $coffee_type $0 for @args" if @args == 1; "/me brews up a $flavor cup of $coffee_type $0 @args"; }
action: /say How to compare floats: http://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/ -- More information about floats: http://randomascii.wordpress.com/2012/09/09/game-developer-magazine-floating-point/ and http://docs.sun.com/source/806-3568/ncg_goldberg.html
action: /say Please paste a *compilable* test-case that exhibits your symptoms. If the code is incomplete, we cannot discount potential errors or undefined behavior elsewhere in your code, nor can we use our tools to debug. Please do not waste our time this way.
action: /say DAE hate Perl? So somebody saw some joke code about Perl one-liners being a mix of nonsensical punctuation and now they think all Perl code is like that? It's like if they went to IOCCC and then started being extremely vocal about how all C code is like IOCCC. LEL.
action: "does a slow Fandango" "dances an Irish jig" "does the bunny hop" "does the Macarena" "does the robot" "shakes it like a Polaroid picture" "Charlestons furiously"
action: /say "It doesn't work!" is not very informative for the people trying to help you. Please describe what you think may be wrong, what results you expected to get and what instead actually happens. Pasting a compilable test-case and/or compiler messages to http://ideone.com/ may be helpful.
action: /say If you have an error message please paste the actual error message. Do not say "I have an error in my code." Please paste the relevant code at http://ideone.com with comments indicating the line numbers and a description of what you're trying to accomplish. Do not ask to "find the error in my code, plzz".
action: /say What everybody should know about floating-point arithmetic: http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html and http://randomascii.wordpress.com/2012/09/09/game-developer-magazine-floating-point/
action: /say Greenspun's Tenth Rule of Programming: "Any sufficiently complicated C or Fortran program contains an ad-hoc, informally-specified bug-ridden slow implementation of half of Common Lisp."
action: /say <grot> I remember the relief of waking up one morning (sane) in a hospital bed, after a night of terror after smoking cannbis, having freaked out completely and developed symptoms that went beyond ordinary panic attacks
action: the act of trying to write code without learning the language, or to use a library without reading the documentation. How guesscoders even get anything done is anyone's guess.
action: /say "Given..Want": What do you have to work with? What's the desired goal? Between them is the resulting Process. Now ask yourself: WHY am I doing this? Why THIS way?
action: a vicious species, loyal only to Baughn. Attempts to wrest control of the Herring Hordes can result in consequences similar to http://fukung.net/v/2833/15cod.jpg .
action: /say We can help with homework, as long as it's within the spirit of the assignment. We won't do it for you, though. Ask questions such as "Why is it that ... ?" rather than "Show me how to ..."
action: /say What you're attempting is akin to an apprentence carpenter attempting to construct an entire house without having learned how to measure. In other words, there will be a lot of holes -- if the entire contraption doesn't fall apart completely.
action: "I don't know." "If you investigate a $sizes amount further, you can figure it out." "Are you thinking clearly?" "Are you sure you're not a $sizes $idiots?" "Read the $manuals, you $sizes $idiots."
action: rudimentary program loader with system libraries included. See: https://github.com/cheery/icicle-binfmt See Also: http://en.wikipedia.org/wiki/Loader_(computing)
action: "your mum circulates like a public key, servicing more requests than HTTP." "if your mom was a collection class, her insert method would be public." "you're so lame you could encode mp3's." "keep trying; fizzbuzz isn't that hard." "what do you and structs have in common? No class." "your code is so wretched the cache invalidates as it loads it."
action: /say A memory leak occurs when a dynamically allocated memory is left without the free() counterpart being called. Valgrind is a tool to check memory leaks.
action: /say Link-time optimization is a type of program optimization performed by a compiler to a program at link time. Link time optimization occurs in programming languages that compile programs on a file-by-file basis (such as C and Fortran), rather than all at once (such as Java).
action: /say If there's more than one possible outcome of a job or task, and one of those outcomes will result in disaster or an undesirable consequence, then somebody will do it that way.
action: /say In order to speak in this channel, you must register your IRC nick-name through NickServ. See `/msg nickserv help register` or follow the guide at http://www.wikihow.com/Register-a-User-Name-on-Freenode
action: "Whew, you lucked out" "The needle was clean!" "The fresh corpse was clean!" "The prosititute didn't have aids!" "The teddy bear was aids free." "The homeless bum didn't have aids!" "Your hands were aids-free that time." "$who_answers didn't have aids . . . yet!" "$who_answers is aids-free at this time."
action: /say If you don't have a book then you are wasting your time and ours. The only good way to learn C is through a book. If you are too cheap to buy a book then just give up and learn something else that doesn't require a book. In either case, go away until you have a book.
action: /say pastebin.com and similar pastebins have ugly colour contrast, hard-to-read fonts, and insert pesky line numbers into the clipboard. Please use a better pastebin, like http://codepad.org
action: /say Please do not poll the channel asking if anyone knows about or has used something. Just ask your specific question about it and if someone knows then they'll answer.
action: /say If you're working on this, you really shouldn't be asking C questions. All your C questions should have been answered years ago or you probably aren't ready/prepared for this project.
action: /say For quotegrab commands: http://www.iso-9899.info/wiki/Candide#Quotegrabs -- For a table of grabbed quotes: http://www.iso-9899.info/candide/quotegrabs.html
action: /say Usage: quote [text] [--author <author>] -- If you use `quote` without arguments, it returns a random quote; if you use it with an argument, it searches for quotes containing that text; if you add --author <name> at the end, it searches for a quote by that author; if you specify text and --author, it searches for quotes by that author, containing that text.
action: /say Read A Fucking Book - Your primary guide for learning C should be a good book (see ,books). You must not expect to become a proficient C programmer just by reading crappy online `tuts', staring at other people's code, and/or boring us to death by asking dozens of exceedingly trivial questions.
action: /say RAS Syndrome -- which stands for "Redundant Acronym Syndrome Syndrome" -- is a tongue-in-cheek name that describes the problem of unnecessary repetition hidden by an acronym. http://suite101.com/article/redundant-acronyms-a65825
action: { return "/say Nonsense! Zhivago is a gentleman and a scholar." if $nick eq "Zhivago" or "@args" =~ /zhivago/i; return "/me $attacks $args[0] with a $sizes $colors manual." }
action: "pinches a loaf" "drops the kids off" "lays some cable" "builds a log cabin" "takes a tour of doody" "drops a tootsie roll" "releases the kraken"
action: /say Let's say you want to buy a pair of shoes, right? You come to my shoe store and I ask you what size your feet are. You respond, "I like red." I say, "That's nice, I'll look for some red shoes. What size are your feet?" And you respond, "I really like red." Try to answer our questions, please.
action: C++ isn't a superset because (a) some C programs are not legal C++ programs (b) some C programs behave differently when treated as C++ programs.
action: /say If someone in the channel is asking pointed questions of a specific individual, please do not answer their questions if you are not that individual. We're sure you're quite smart and capable, but the point is to let the individual infer the answer himself. You can give a programmer Coca-cola, but if you teach them how to carbonate coffee ...
action: not just accepting that the person asking knows what they are doing and has merely forgotten the proper forms to use. Rather, they need insight into what solutions exist to solve the problems they face; for which, there can be no better tool than a clear explanation of the problem, even if you must draw it out of them millimeter by torturous millimeter.
action: /say A testcase is a minimal compilable example exhibiting your symptoms. "Minimal" means just the bare essentials required to illustrate your question. "Compilable" means that there is enough code to compile it on our machines, and therefore use our debuggers. Please paste a testcase at http://ideone.com or http://codepad.org to help us assist you.
action: /say In cryptography, a timing attack is a side channel attack in which the attacker attempts to compromise a cryptosystem by analyzing the time taken to execute cryptographic algorithms. Learn more at http://www.cs.hmc.edu/~mike/public_html/courses/security/s06/projects/dan.pdf
action: /say We understood you the first time, and answered already; you may not have understood the answers. Instead of ignoring them and repeating your question, find out what they mean.
action: /say Use the right tool for the job. Someone once said, "if the only tool you have is a hammer, you tend to see every problem as a nail." Avoid placing artificial limitations on your projects by keeping an open mind and learning more tools, as your skills improve.
action: a memory debugging tool. When your program is exhibiting erratic behavior, it may be due to a memory error such as overrunning a buffer or not updating the pointer after a realloc. Try running your program with valgrind; it will save you a lot of time.
action: /say A video testcase is a minimal viewable video exhibiting your problem. "Minimal" means just the bare essentials required to illustrate your problem. Please record a video testcase at http://www.youtube.com to help us assist you.
action: "I don't know." "Because the $sizes $colors $animals made it that way." "That's just how it is." "If you just investigate a $sizes amount further, you can figure it out." "Because I said so!" "Are you thinking clearly?" "Are you sure you're not a $sizes $idiots?"
action: a thirty-two bit extension and graphical shell to a sixteen-bit patch to an eight-bit operating system originally coded for a four-bit microprocessor which was written by a two-bit company that can't stand one bit of competition.
action: /say The XY problem: You want to do X, but don't know how. You think you can solve it using Y, but don't know how to do that, either. You ask about Y, which is a strange thing to want to do. Just ask about X.
