pidfile(3) - NetBSD Manual Pages

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PIDFILE(3)              NetBSD Library Functions Manual             PIDFILE(3)


NAME

     pidfile -- write a daemon pid file


LIBRARY

     System Utilities Library (libutil, -lutil)


SYNOPSIS

     #include <util.h>

     int
     pidfile(const char *path);


DESCRIPTION

     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 automati-
     cally, unless the program receives a fatal signal.

     If path is NULL or a plain basename (a name containing no directory com-
     ponents), 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
     getprogname(3) otherwise.

     If path is an absolute or relative path (i.e. it contains the `/' charac-
     ter), 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 sup-
     plied.  If called with a new path, pidfile() will remove the old pid file
     and write the new one.


RETURN VALUES

     pidfile() returns 0 on success and -1 on failure.


SEE ALSO

     atexit(3)


HISTORY

     The pidfile() function call appeared in NetBSD 1.5.  Support for creating
     pid files in any arbitrary path was added in NetBSD 6.0.


BUGS

     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 6.0                      March 23, 2011                      NetBSD 6.0