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

       Written by Rob Browning <rlb@defaultvalue.org>

0.2.0                                              2024-12-10                                  lockfile-progs(1)

       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.

Lockingafileduringalengthyprocess:

         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

0
           For lockfile-check this indicates that a valid lock exists, otherwise it  just  indicates  successful
           program execution.

       Not0
           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 encountered.

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

--version
           Report the version to standard output and exit.

       -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, lockfile-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.

       -rretry-count, --retryretry-count
           Try  to  lock filenameretry-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.

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

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

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