lockfile-progs(1) - man - phpMan

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



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

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/<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.


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

       -p, --use-pid
           Write  the  parent  process id (PPID) 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 and lockfile-check.  NOTE: this
           option will not work correctly between machines sharing a filesystem.

       -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 225 seconds 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, otherwise it just indicates
           successful program execution.

       Not 0
           For lockfile-check a non-zero exit status indicates that the specified lock does not  ex‐
           ist 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 <rlb AT defaultvalue.org>



0.1.19                                       2021-09-03                            lockfile-progs(1)