1.\" $OpenBSD: pidfile.3,v 1.4 2001/12/01 23:47:37 miod Exp $ 2.\" $NetBSD: pidfile.3,v 1.2 2001/04/12 22:34:31 sommerfeld Exp $ 3.\" 4.\" Copyright (c) 1999 The NetBSD Foundation, Inc. 5.\" All rights reserved. 6.\" 7.\" This code is derived from software contributed to The NetBSD Foundation 8.\" by Jason R. Thorpe. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the NetBSD 21.\" Foundation, Inc. and its contributors. 22.\" 4. Neither the name of The NetBSD Foundation nor the names of its 23.\" contributors may be used to endorse or promote products derived 24.\" from this software without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36.\" POSSIBILITY OF SUCH DAMAGE. 37.\" 38.Dd June 5, 1999 39.Dt PIDFILE 3 40.Os 41.Sh NAME 42.Nm pidfile 43.Nd write a daemon pid file 44.Sh SYNOPSIS 45.Fd #include <util.h> 46.Ft int 47.Fn pidfile "const char *basename" 48.Sh DESCRIPTION 49.Fn pidfile 50writes a file containing the process ID of the program to the 51.Pa /var/run 52directory. 53The file name has the form 54.Pa /var/run/basename.pid . 55If the 56.Ar basename 57argument is NULL, 58.Nm 59will determine the program name and use that instead. 60.Pp 61The pid file can be used as a quick reference if 62the process needs to be sent a signal. 63When the program exits, the pid file will be removed automatically, 64unless the program receives a fatal signal. 65.Sh RETURN VALUES 66.Fn pidfile 67returns 0 on success and -1 on failure. 68.Sh SEE ALSO 69.Xr atexit 3 70.Sh HISTORY 71The 72.Nm 73function call appeared in 74.Ox 3.0 . 75.Sh CAVEATS 76If 77.Fn pidfile 78is called multiple times with different 79.Ar basename , 80only the last pidfile will be removed upon exit. 81.Pp 82.Fn pidfile 83uses 84.Fn atexit 85to ensure the pidfile is unlinked at program exit. 86However, programs that use the 87.Fn _exit 88function (for example, in signal handlers) 89will not trigger this behaviour. 90