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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/<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, 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.


-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 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 <rlb@defaultvalue.org>







  

    2021-09-03
    0.1.19