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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, 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 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, otherwise it just indi-
cates 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 encoun-
tered.
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>
0.1.12 2008-02-10 lockfile-progs(1)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
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