lockfile-check

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



NAME
       lockfile-progs  - command-line programs to safely lock and unlock files
       and mailboxes (via liblockfile).

SYNOPSIS
       mail-lock [--use-pid] [--retry retry-count]
       mail-unlock
       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

DESCRIPTION
       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/,  where    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  lock‐
       file_create(3) manpage.

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


OPTIONS
       -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 lock‐
           file-create, lockfile-remove, lockfile-touch, or lockfile-check.

       -p, --use-pid
           Write the current process id (PID) to the lockfile whenever a lock‐
           file  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  lock‐
           file-touch  and  mail-touchlock.  When not provided, these commands
           will run forever, touching the lock once every minute until killed.

       -r retry-count, --retry-count 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.


EXAMPLES
       Locking a file during a lengthy process:

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


EXIT STATUS
       0
           For  lockfile-check this indicates that a valid lock exists, other‐
           wise it just indicates successful program execution.

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

SEE ALSO
       maillock(3)
       touchlock(3)
       mailunlock(3)
       lockfile_create(3)
       lockfile_remove(3)
       lockfile_touch(3)
       lockfile_check(3)


AUTHOR
       Written by Rob Browning 



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