1.\" $NetBSD: pidfile.3,v 1.8 2002/10/01 19:36:30 wiz Exp $ 2.\" 3.\" Copyright (c) 1999 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Jason R. Thorpe. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.Dd June 5, 1999 38.Dt PIDFILE 3 39.Os 40.Sh NAME 41.Nm pidfile 42.Nd write a daemon pid file 43.Sh LIBRARY 44.Lb libutil 45.Sh SYNOPSIS 46.Fd #include \*[Lt]util.h\*[Gt] 47.Ft int 48.Fn pidfile "const char *basename" 49.Sh DESCRIPTION 50.Fn pidfile 51writes a file containing the process ID of the program to the 52.Pa /var/run 53directory. 54The file name has the form 55.Pa /var/run/basename.pid . 56If the 57.Ar basename 58argument is NULL, 59.Nm 60will determine the program name and use that instead. 61.Pp 62The pid file can be used as a quick reference if 63the process needs to be sent a signal. 64When the program exits, the pid file will be removed automatically, unless 65the program receives a fatal signal. 66.Pp 67Note that only the first invocation of 68.Nm 69causes a pid file to be written; subsequent invocations have no effect 70unless a new 71.Ar basename 72is supplied. 73If called with a new 74.Ar basename , 75.Fn pidfile 76will remove the old pid file and write the new one. 77.Sh RETURN VALUES 78.Fn pidfile 79returns 0 on success and -1 on failure. 80.Sh SEE ALSO 81.Xr atexit 3 82.Sh HISTORY 83The 84.Nm 85function call appeared in 86.Nx 1.5 . 87.Sh BUGS 88.Fn pidfile 89uses 90.Xr atexit 3 91to ensure the pidfile is unlinked at program exit. 92However, programs that use the 93.Xr _exit 2 94function (for example, in signal handlers) 95will not trigger this behaviour. 96