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Add prospective manual page for spawnd

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C. McEnroe 2020-08-13 17:34:58 -04:00
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.Dd August 13, 2020
.Dt SPAWND 8
.Os
.
.Sh NAME
.Nm spawnd
.Nd process supervisor
.
.Sh SYNOPSIS
.Nm
.Op Fl d
.Op Fl C Ar path
.Op Fl c Ar control
.Op Fl f Ar spawntab
.Op Fl g Ar group
.Op Fl p Ar pidfile
.Op Fl s Ar stopexits
.Op Fl t Ar interval
.Op Fl u Ar user
.
.Sh DESCRIPTION
The
.Nm
daemon
is a supervisor for processes
with the following behavior:
.Bl -enum
.It
The process runs in the foreground,
not as a daemon.
.It
The process logs to standard output or standard error.
.It
The process handles errors by exiting
and expects to be restarted.
.It
The process indicates its reason for exiting with
.Xr sysexits 3 .
.El
.
.Pp
The
.Nm
daemon spawns processes for a list of
.Em services ,
redirects their output to syslog,
and restarts the processes when they exit
according to their exit status.
Exponential backoff is applied to restarts.
.
.Pp
The list of services is defined in a
.Xr spawntab 5
file.
The services managed by
.Nm
can be controlled
through a named pipe.
The
.Xr spawn 8
utility is a wrapper
around the named pipe,
and its manual page
describes the control command format.
.
.Pp
The arguments are as follows:
.Bl -tag -width Ds
.It Fl C Ar path
Change directory to
.Ar path
before starting services.
By default the working directory is
.Pa / .
.
.It Fl c Ar control
Set the path of the named pipe
used for control.
.
.It Fl d
Do not run as a daemon.
.
.It Fl f Ar spawntab
Set the path of the
.Xr spawntab 5
file.
.
.It Fl g Ar group
Change group to
.Ar group
before starting services.
If
.Fl u
is used,
the default group is the user's group.
.
.It Fl p Ar pidfile
Write the PID of the
.Nm
process to
.Ar pidfile .
.
.It Fl s Ar stopexits
Set the list of exit statuses
for which a restart will not be attempted.
The
.Ar stopexits
argument is a comma-separated list of integers.
The default list contains the values of
.Dv EX_USAGE ,
.Dv EX_DATAERR ,
.Dv EX_NOINPUT ,
.Dv EX_OSFILE ,
.Dv EX_CANTCREAT ,
.Dv EX_CONFIG
defined in
.Xr sysexits 3 ,
as well as 127.
.
.It Fl t Ar interval
Set the initial interval between restarts
in milliseconds.
The default interval is 1000.
.
.It Fl u Ar user
Change user to
.Ar user
before starting services.
.El
.
.Pp
When the
.Nm
daemon receives the
.Dv HUP
signal,
the
.Xr spawntab 5
file is reloaded.
Modified services
are not automatically restarted,
newly added services
are not automatically started,
and removed services
are not automatically stopped.
.
.Pp
When the
.Nm
daemon receives the
.Dv TERM
signal,
the control named pipe is closed,
all services are stopped,
and
.Nm
exits.
.
.Sh ENVIRONMENT
Services are started
with empty environments
apart from the following:
.Bl -tag -width Ds
.It Ev LOGNAME , Ev USER
Set to the name of the user specified by
.Fl u .
.It Ev HOME
Set to the home directory of the user specified by
.Fl u .
.It Ev SHELL
Set to
.Pa /bin/sh .
.It Ev PATH
Set to the system default defined by
.Dv _PATH_DEFPATH
in
.In paths.h .
.El
.
.Sh FILES
.Bl -tag -width Ds
.It Pa /usr/local/etc/spawntab
The default path of the
.Xr spawntab 5
file.
.It Pa /var/run/spawnd.pipe
The default path of the named pipe
used for control.
.El
.
.Sh SEE ALSO
.Xr spawntab 5 ,
.Xr spawn 8
.
.Sh AUTHORS
.An June Bug Aq Mt june@causal.agency