106 lines
3.1 KiB
Groff
106 lines
3.1 KiB
Groff
.\" $NetBSD: pidfile.3,v 1.13 2011/03/29 13:55:37 jmmv Exp $
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.\"
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.\" Copyright (c) 1999 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Jason R. Thorpe.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd March 23, 2011
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.Dt PIDFILE 3
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.Os
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.Sh NAME
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.Nm pidfile
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.Nd write a daemon pid file
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.Sh LIBRARY
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.Lb libutil
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.Sh SYNOPSIS
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.In util.h
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.Ft int
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.Fn pidfile "const char *path"
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.Sh DESCRIPTION
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.Fn pidfile
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creates a file containing the process ID of the caller program.
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The pid file can be used as a quick reference if
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the process needs to be sent a signal.
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When the program exits, the pid file is removed automatically, unless
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the program receives a fatal signal.
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.Pp
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If
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.Ar path
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is
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.Dv NULL
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or a plain basename (a name containing no directory components), the pid file
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is created in the
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.Pa /var/run
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directory.
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The file name has the form
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.Pa /var/run/basename.pid .
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The basename part is either the value of
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.Ar path
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if it was not
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.Dv NULL ,
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or the program name as returned by
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.Xr getprogname 3
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otherwise.
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.Pp
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If
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.Ar path
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is an absolute or relative path (i.e. it contains the
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.Sq /
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character),
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the pid file is created in the provided location.
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.Pp
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Note that only the first invocation of
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.Fn pidfile
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causes a pid file to be written; subsequent invocations have no effect
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unless a new
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.Ar path
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is supplied.
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If called with a new
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.Ar path ,
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.Fn pidfile
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will remove the old pid file and write the new one.
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.Sh RETURN VALUES
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.Fn pidfile
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returns 0 on success and -1 on failure.
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.Sh SEE ALSO
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.Xr atexit 3
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.Sh HISTORY
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The
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.Fn pidfile
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function call appeared in
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.Nx 1.5 .
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Support for creating pid files in any arbitrary path was added in
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.Nx 6.0 .
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.Sh BUGS
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.Fn pidfile
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uses
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.Xr atexit 3
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to ensure the pid file is unlinked at program exit.
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However, programs that use the
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.Xr _exit 2
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function (for example, in signal handlers)
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will not trigger this behaviour.
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