diff --git a/.gitignore b/.gitignore
index a63d5b5..a4918e7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@ __pycache__/
 *~
 *.save*
 *.db
+pylink.pid
diff --git a/main.py b/main.py
index 5db0098..9f35987 100755
--- a/main.py
+++ b/main.py
@@ -204,6 +204,10 @@ if __name__ == '__main__':
         sys.exit(2)
     protocols_folder = [os.path.join(os.getcwd(), 'protocols')]
 
+    # Write a PID file.
+    with open('pylink.pid', 'w') as f:
+        f.write(str(os.getpid()))
+
     # Import plugins first globally, because they can listen for events
     # that happen before the connection phase.
     utils.plugins.append(coreplugin)