man > mail-touchlock(1)

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)