View Source: lockfile-create(1) - Waikato Linux Users Group

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!!NAME

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


!!SYNOPSIS

__mail-lock__ [[ --retry ''retry-count'' ] %%%
__mail-unlock__ %%%
__mail-touchlock__ [[ --oneshot ]

__lockfile-create__ [[ --retry ''retry-count'' ] ''filename'' %%%
__lockfile-remove__ ''filename'' %%%
__lockfile-touch__ [[ --oneshot ] ''filename'' %%%

!!DESCRIPTION

__lockfile-progs__ provide a method 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.

Each of the mail locking commands is applied to the file /var/spool/mail/

* __lockfile-create:__ lock a given file.
* __lockfile-remove:__ remove the lock on a given file.
* __lockfile-touch:__ touch the lock on a given file.

Creating a file lock includes creating the file ''filename''.lock.  This requires that the user running lockfile-create have write permission to the directory where ''filename'' resides.

Once a file is locked, the lock must be touched at least once every five minutes, or it will be considered stale and a subsequent attempt to lock the file will succeed. For both of the locking commands __(mail-touchlock__ and __lockfile-touch),__ the --oneshot argument causes the program to touch the lock and exit immediately. Otherwise the program will loop forever, touching the lock once every minute until it is killed.

For both of the locking commands __(mail-lock__ and __lockfile-create),__ the --retry argument specifies (as an integer) the maximum number of times to retry locking the file before giving up if attempts are failing. Each retry will be delayed a little longer than the last (in 5 second increments) until a maximum delay of one minute between retries is reached. The default retry count is 9 which, if all 9 attempts to lock the file fail, will give up after 180 seconds (3 minutes).

!!EXAMPLES

__Locking a file during a lengthy process:__ lockfile-create /some/file lockfile-touch /some/file

!!EXIT STATUS

* __0__ Successful program execution.
* __NOT-0__ Some problem was encountered.

!!SEE ALSO

maillock(3), touchlock(3), mailunlock(3), lockfile-create(1), lockfile-remove(1), lockfile-touch(1), lockfile_create(3), lockfile_remove(3),
lockfile_touch(3).

!!HISTORY

1998 - Written by Rob Browning

7 pages link to lockfile-create(1):

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Last edited on Monday, February 24, 2003 5:46:32 pm by CraigBox

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