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LOCKF(1)               DragonFly General Commands Manual              LOCKF(1)

NAME
     lockf -- execute a command while holding a file lock

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

DESCRIPTION
     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 completes.

     -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.

EXIT STATUS
     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
                   process.

     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
     flock(2), sysexits(3)

HISTORY
     A lockf utility first appeared in FreeBSD 2.2.

AUTHORS
     John Polstra <jdp@polstra.com>

DragonFly 4.3                    July 7, 1998                    DragonFly 4.3