lockfile-progs
Section: Lockfile programs (1)
Updated: 2008-02-10
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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 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 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>
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- OPTIONS
-
- EXAMPLES
-
- EXIT STATUS
-
- SEE ALSO
-
- AUTHOR
-
© Andrew Scott 2006 -
2024,
All Rights Reserved