freebsd-skq/usr.bin/lockf/lockf.1

.\"
.\" Copyright (C) 1998 John D. Polstra.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY JOHN D. POLSTRA AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL JOHN D. POLSTRA OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 7, 1998
.Os
.Dt LOCKF 1
.Sh NAME
.Nm lockf
.Nd execute a command while holding a file lock
.Sh SYNOPSIS
.Nm
.Op Fl ks
.Op Fl t Ar seconds
.Ar file
.Ar command
.Op Ar arguments
.Sh DESCRIPTION
The
.Nm
utility acquires an exclusive lock on a
.Ar file ,
creating it if necessary,
.Bf Em
and removing the file on exit unless explicitly told not to.
.Ef
While holding the lock, it executes a
.Ar command
with optional
.Ar arguments .
After the
.Ar command
completes,
.Nm
releases the lock, and removes the
.Ar file
unless the
.Fl k
option is specified.
.Bx Ns -style
locking is used, as described in
.Xr flock 2 ;
the mere existence of the
.Ar file
is not considered to constitute a lock.
.Pp
The following options are supported:
.Bl -tag -width Fl
.It Fl k
Causes the lock file to be kept (not removed) after the command
completes.
.It Fl s
Causes
.Nm
to operate silently.
Failure to acquire the lock is indicated only in the exit status.
.It Fl t Ar seconds
Specifies a timeout for waiting for the lock.
By default,
.Nm
waits indefinitely to acquire the lock.
If a timeout is specified with this option,
.Nm
will wait at most the given number of
.Ar seconds
before giving up.
A timeout of 0 may be given, in which case
.Nm
will fail unless it can acquire the lock immediately.
When a lock times out,
.Ar command
is
.Em not
executed.
.El
.Pp
In no event will
.Nm
break a lock that is held by another process.
.Sh EXIT STATUS
If
.Nm
successfully acquires the lock, it returns the exit status produced by
.Ar command .
Otherwise, it returns one of the exit codes defined in
.Xr sysexits 3 ,
as follows:
.Bl -tag -width F_CANTCREATX
.It Dv EX_TEMPFAIL
The specified lock file was already locked by another process.
.It Dv EX_CANTCREAT
The
.Nm
utility
was unable to create the lock file, e.g., because of insufficient access
privileges.
.It Dv EX_USAGE
There was an error on the
.Nm
command line.
.It Dv EX_OSERR
A system call (e.g., fork) failed unexpectedly.
.El
.Sh SEE ALSO
.Xr flock 2 ,
.Xr sysexits 3
.Sh HISTORY
A
.Nm
utility first appeared in
.Fx 2.2 .
.Sh AUTHORS
.An John Polstra Aq jdp@polstra.com .
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.\"`
Add a "-k" option, to specify that the lock file should be kept rather than removed. Submitted by: Nick Barnes <Nick.Barnes@pobox.com> 1998-07-08 05:29:05 +00:00			`.\" Copyright (C) 1998 John D. Polstra. All rights reserved.`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.\"`
			`.\" Redistribution and use in source and binary forms, with or without`
			`.\" modification, are permitted provided that the following conditions`
			`.\" are met:`
			`.\" 1. Redistributions of source code must retain the above copyright`
			`.\" notice, this list of conditions and the following disclaimer.`
			`.\" 2. Redistributions in binary form must reproduce the above copyright`
			`.\" notice, this list of conditions and the following disclaimer in the`
			`.\" documentation and/or other materials provided with the distribution.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY JOHN D. POLSTRA AND CONTRIBUTORS ``AS IS'' AND
			`.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE`
			`.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE`
			`.\" ARE DISCLAIMED. IN NO EVENT SHALL JOHN D. POLSTRA OR CONTRIBUTORS BE LIABLE`
			`.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL`
			`.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS`
			`.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)`
			`.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT`
			`.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY`
			`.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF`
			`.\" SUCH DAMAGE.`
			`.\"`
$Id$ -> $FreeBSD$ 1999-08-28 01:08:13 +00:00			`.\" $FreeBSD$`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.\"`
Add a "-k" option, to specify that the lock file should be kept rather than removed. Submitted by: Nick Barnes <Nick.Barnes@pobox.com> 1998-07-08 05:29:05 +00:00			`.Dd July 7, 1998`
mdoc(7) police: removed HISTORY info from the .Os call. 2001-07-10 14:16:33 +00:00			`.Os`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.Dt LOCKF 1`
			`.Sh NAME`
			`.Nm lockf`
			`.Nd execute a command while holding a file lock`
			`.Sh SYNOPSIS`
			`.Nm`
Add a "-k" option, to specify that the lock file should be kept rather than removed. Submitted by: Nick Barnes <Nick.Barnes@pobox.com> 1998-07-08 05:29:05 +00:00			`.Op Fl ks`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.Op Fl t Ar seconds`
			`.Ar file`
			`.Ar command`
			`.Op Ar arguments`
			`.Sh DESCRIPTION`
			`The`
			`.Nm`
			`utility acquires an exclusive lock on a`
			`.Ar file ,`
Document a couple of gotchas. 2005-05-26 22:30:12 +00:00			`creating it if necessary,`
Markup and wording fixes. Approved by: re (blanket) 2005-06-14 11:50:53 +00:00			`.Bf Em`
Fix all the spelling mistakes I could find in the man pages for words that have at least 3 characters. MFC after: 1 week Thanks to: Music band ``Chingon'' for keeping me company while searching for these. 2005-07-31 03:30:48 +00:00			`and removing the file on exit unless explicitly told not to.`
Markup and wording fixes. Approved by: re (blanket) 2005-06-14 11:50:53 +00:00			`.Ef`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`While holding the lock, it executes a`
			`.Ar command`
			`with optional`
			`.Ar arguments .`
			`After the`
			`.Ar command`
			`completes,`
			`.Nm`
Add a "-k" option, to specify that the lock file should be kept rather than removed. Submitted by: Nick Barnes <Nick.Barnes@pobox.com> 1998-07-08 05:29:05 +00:00			`releases the lock, and removes the`
			`.Ar file`
			`unless the`
			`.Fl k`
mdoc(7) police: s/BSD/.Bx/ where appropriate. 2001-08-14 10:01:54 +00:00			`option is specified.`
			`.Bx Ns -style`
			`locking is used, as described in`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.Xr flock 2 ;`
Remove whitespace at EOL. 2001-07-15 08:06:20 +00:00			`the mere existence of the`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.Ar file`
			`is not considered to constitute a lock.`
			`.Pp`
			`The following options are supported:`
			`.Bl -tag -width Fl`
Add a "-k" option, to specify that the lock file should be kept rather than removed. Submitted by: Nick Barnes <Nick.Barnes@pobox.com> 1998-07-08 05:29:05 +00:00			`.It Fl k`
			`Causes the lock file to be kept (not removed) after the command`
			`completes.`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.It Fl s`
			`Causes`
			`.Nm`
			`to operate silently.`
			`Failure to acquire the lock is indicated only in the exit status.`
			`.It Fl t Ar seconds`
Mechanically kill hard sentence breaks. 2004-07-02 22:22:35 +00:00			`Specifies a timeout for waiting for the lock.`
			`By default,`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.Nm`
			`waits indefinitely to acquire the lock.`
			`If a timeout is specified with this option,`
			`.Nm`
			`will wait at most the given number of`
			`.Ar seconds`
Mechanically kill hard sentence breaks. 2004-07-02 22:22:35 +00:00			`before giving up.`
			`A timeout of 0 may be given, in which case`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.Nm`
			`will fail unless it can acquire the lock immediately.`
Document a couple of gotchas. 2005-05-26 22:30:12 +00:00			`When a lock times out,`
			`.Ar command`
			`is`
			`.Em not`
			`executed.`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.El`
			`.Pp`
			`In no event will`
			`.Nm`
			`break a lock that is held by another process.`
Added the EXIT STATUS section where appropriate. 2005-01-17 07:44:44 +00:00			`.Sh EXIT STATUS`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`If`
			`.Nm`
On failure, return various exit codes from <sysexits.h>. In particular, return EX_TEMPFAIL if the file was already locked. This makes it easier to distinguish between lock collisions and failures within the command being executed. Also, don't complain if the unlink() fails in the cleanup handler. It doesn't matter anyway, and it obscured the exit status returned from the command that was executed. 1997-01-09 19:53:21 +00:00			`successfully acquires the lock, it returns the exit status produced by`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.Ar command .`
On failure, return various exit codes from <sysexits.h>. In particular, return EX_TEMPFAIL if the file was already locked. This makes it easier to distinguish between lock collisions and failures within the command being executed. Also, don't complain if the unlink() fails in the cleanup handler. It doesn't matter anyway, and it obscured the exit status returned from the command that was executed. 1997-01-09 19:53:21 +00:00			`Otherwise, it returns one of the exit codes defined in`
			`.Xr sysexits 3 ,`
			`as follows:`
			`.Bl -tag -width F_CANTCREATX`
			`.It Dv EX_TEMPFAIL`
			`The specified lock file was already locked by another process.`
			`.It Dv EX_CANTCREAT`
Use `The .Nm utility' 2002-04-20 12:18:28 +00:00			`The`
On failure, return various exit codes from <sysexits.h>. In particular, return EX_TEMPFAIL if the file was already locked. This makes it easier to distinguish between lock collisions and failures within the command being executed. Also, don't complain if the unlink() fails in the cleanup handler. It doesn't matter anyway, and it obscured the exit status returned from the command that was executed. 1997-01-09 19:53:21 +00:00			`.Nm`
Use `The .Nm utility' 2002-04-20 12:18:28 +00:00			`utility`
On failure, return various exit codes from <sysexits.h>. In particular, return EX_TEMPFAIL if the file was already locked. This makes it easier to distinguish between lock collisions and failures within the command being executed. Also, don't complain if the unlink() fails in the cleanup handler. It doesn't matter anyway, and it obscured the exit status returned from the command that was executed. 1997-01-09 19:53:21 +00:00			`was unable to create the lock file, e.g., because of insufficient access`
			`privileges.`
			`.It Dv EX_USAGE`
			`There was an error on the`
			`.Nm`
			`command line.`
			`.It Dv EX_OSERR`
			`A system call (e.g., fork) failed unexpectedly.`
			`.El`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.Sh SEE ALSO`
On failure, return various exit codes from <sysexits.h>. In particular, return EX_TEMPFAIL if the file was already locked. This makes it easier to distinguish between lock collisions and failures within the command being executed. Also, don't complain if the unlink() fails in the cleanup handler. It doesn't matter anyway, and it obscured the exit status returned from the command that was executed. 1997-01-09 19:53:21 +00:00			`.Xr flock 2 ,`
.Sh AUTHOR -> .Sh AUTHORS. Use .An/.Aq. 1998-03-23 07:48:45 +00:00			`.Xr sysexits 3`
Add history. 2000-12-10 01:10:54 +00:00			`.Sh HISTORY`
Use `The .Nm utility' 2002-04-20 12:18:28 +00:00			`A`
Add history. 2000-12-10 01:10:54 +00:00			`.Nm`
Use `The .Nm utility' 2002-04-20 12:18:28 +00:00			`utility first appeared in`
Add history. 2000-12-10 01:10:54 +00:00			`.Fx 2.2 .`
Initial import of the lockf utility. It executes an arbitrary command while holding an exclusive lock on a file. 1997-01-08 20:12:59 +00:00			`.Sh AUTHORS`
.Sh AUTHOR -> .Sh AUTHORS. Use .An/.Aq. 1998-03-23 07:48:45 +00:00			`.An John Polstra Aq jdp@polstra.com .`