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lockfile-progs(1)			Lockfile programs			lockfile-progs(1)

       lockfile-progs  - command-line programs to safely lock and unlock files and mailboxes (via

       mail-lock [--use-pid] [--retry retry-count]
       mail-touchlock [--oneshot]

       lockfile-create [--use-pid] [--retry retry-count] [--lock-name] filename
       lockfile-remove [--lock-name] filename
       lockfile-touch [--oneshot] [--lock-name] filename
       lockfile-check [--use-pid] [--lock-name] filename

       Lockfile-progs provides a set a programs that can be used to lock and unlock mailboxes and
       files safely (via liblockfile):

	   mail-lock - lock the current user's mailbox
	   mail-unlock - unlock the current user's mailbox
	   mail-touchlock - touch the lock on the current user's mailbox

	   lockfile-create - lock a given file
	   lockfile-remove - remove the lock on a given file
	   lockfile-touch - touch the lock on a given file
	   lockfile-check - check the lock on a given file

       By  default,  the  filename  argument refers to the name of the file to be locked, and the
       name of the lockfile will be filename .lock.  However,  if  the	--lock-name  argument  is
       specified, then filename will be taken as the name of the lockfile itself.

       Each of the mail locking commands attempts to lock /var/spool/mail/<user>, where <user> is
       the name associated with the effective user ID, as determined by via geteuid(2).

       Once a file is locked, the lock must be touched at least once every five  minutes  or  the
       lock  will  be  considered stale, and subsequent lock attempts will succeed.  Also see the
       --use-pid option and the lockfile_create(3) manpage.

       The lockfile-check command tests whether or not a valid lock already exists.

       -q, --quiet
	   Suppress any output.  Success or failure will only be indicated by the exit status.

       -v, --verbose
	   Enable diagnostic output.

       -l, --lock-name
	   Do not append .lock to the filename.  This option applies  to  lockfile-create,  lock-
	   file-remove, lockfile-touch, or lockfile-check.

       -p, --use-pid
	   Write the current process id (PID) to the lockfile whenever a lockfile is created, and
	   use that pid when checking a lock's validity.  See the lockfile_create(3) manpage  for
	   more  information.  This option applies to lockfile-create, lockfile-remove, lockfile-
	   touch, and lockfile-check.

       -o, --oneshot
	   Touch the lock and exit  immediately.   This  option  applies  to  lockfile-touch  and
	   mail-touchlock.  When not provided, these commands will run forever, touching the lock
	   once every minute until killed.

       -r retry-count, --retry retry-count
	   Try to lock filename retry-count times before giving up.  Each attempt will be delayed
	   a  bit longer than the last (in 5 second increments) until reaching a maximum delay of
	   one minute between retries.	If retry-count is unspecified, the  default  is  9  which
	   will give up after 180 seconds (3 minutes) if all 9 lock attempts fail.

       Locking a file during a lengthy process:

	 lockfile-create /some/file
	 lockfile-touch /some/file &
	 # Save the PID of the lockfile-touch process
	 do-something-important-with /some/file
	 kill "${BADGER}"
	 lockfile-remove /some/file

	   For	lockfile-check	this  indicates that a valid lock exists, otherwise it just indi-
	   cates successful program execution.

       Not 0
	   For lockfile-check a non-zero exit status indicates that the specified lock	does  not
	   exist  or is not valid.  For other programs it indicates that some problem was encoun-


       Written by Rob Browning <rlb@defaultvalue.org>

0.1.12					    2008-02-10				lockfile-progs(1)
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