PIDFILE(3) Library Functions Manual PIDFILE(3)
pidfile -- write a daemon pid file
System Utilities Library (libutil, -lutil)
pidfile(const char *path);
pidfile() creates a file containing the process ID of the caller program.
The pid file can be used as a quick reference if the process needs to be
sent a signal. When the program exits, the pid file is removed
automatically, unless the program receives a fatal signal.
If path is NULL or a plain basename (a name containing no directory
components), the pid file is created in the /var/run directory. The file
name has the form /var/run/basename.pid. The basename part is either the
value of path if it was not NULL, or the program name as returned by
If path is an absolute or relative path (i.e. it contains the `/'
character), the pid file is created in the provided location.
Note that only the first invocation of pidfile() causes a pid file to be
written; subsequent invocations have no effect unless a new path is
supplied. If called with a new path, pidfile() will remove the old pid
file and write the new one.
pidfile() returns 0 on success and -1 on failure.
The pidfile() function call appeared in NetBSD 1.5. Support for creating
pid files in any arbitrary path was added in NetBSD 6.0.
pidfile() uses atexit(3) to ensure the pid file is unlinked at program
exit. However, programs that use the _exit(2) function (for example, in
signal handlers) will not trigger this behaviour.
NetBSD 6.1.5 March 23, 2011 NetBSD 6.1.5