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NAME    [Toc]    [Back]

     lockf -- execute a command while holding a file lock

SYNOPSIS    [Toc]    [Back]

     lockf [-ks] [-t seconds] file command [arguments]

DESCRIPTION    [Toc]    [Back]

     The lockf utility acquires an exclusive lock on a file, creating it if
     necessary.  While holding the lock, it executes a command with optional
     arguments.  After the command completes, lockf releases the lock, and
     removes the file unless the -k option is specified.  BSD-style locking is
     used, as described in flock(2); the mere existence of the file is not
     considered to constitute a lock.

     The following options are supported:

     -k 	 Causes the lock file to be kept (not removed) after the command

     -s 	 Causes lockf to operate silently.  Failure to acquire the
		 lock is indicated only in the exit status.

     -t seconds  Specifies a timeout for waiting for the lock.	By default,
		 lockf waits indefinitely to acquire the lock.	If a timeout
		 is specified with this option, lockf will wait at most the
		 given number of seconds before giving up.  A timeout of 0 may
		 be given, in which case lockf will fail unless it can acquire
		 the lock immediately.

     In no event will lockf break a lock that is held by another process.

DIAGNOSTICS    [Toc]    [Back]

     If lockf successfully acquires the lock, it returns the exit status produced
 by command.	Otherwise, it returns one of the exit codes defined in
     sysexits(3), as follows:

     EX_TEMPFAIL   The specified lock file was already locked by another

     EX_CANTCREAT  The lockf utility was unable to create the lock file, e.g.,
		   because of insufficient access privileges.

     EX_USAGE	   There was an error on the lockf command line.

     EX_OSERR	   A system call (e.g., fork) failed unexpectedly.

SEE ALSO    [Toc]    [Back]

     flock(2), sysexits(3)

HISTORY    [Toc]    [Back]

     A lockf utility first appeared in FreeBSD 2.2.

AUTHORS    [Toc]    [Back]

     John Polstra <jdp@polstra.com>.

FreeBSD 5.2.1			 July 7, 1998			 FreeBSD 5.2.1
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