inn::utils::shlock(3pm) [debian man page]
INN::Utils::Shlock(3pm) InterNetNews Documentation INN::Utils::Shlock(3pm) NAME
INN::Utils::Shlock - Wrapper around the shlock program DESCRIPTION
This Perl module wraps the shlock(1) program so that it can easily be used. Calling shlock is more portable than using flock(2) and its corresponding Perl function because this function does not work as expected on all existing systems. See the shlock(1) documentation for more information. Using INN::Utils::Shlock is straight-forward: use lib '<pathnews>/lib/perl'; use INN::Utils::Shlock; my $lockfile = "myprogram.LOCK"; # Acquire a lock. INN::Utils::Shlock::lock($lockfile); # Do whatever you want. The lock prevents concurrent accesses. # Unlock. INN::Utils::Shlock::unlock($lockfile); These two functions return 1 on success, 0 on failure. For example, the success of (un)locking can be checked as: INN::Utils::Shlock::lock($lockfile) or die "cannot create lock file"; or: if (! INN::Utils::Shlock::lock($lockfile, 4)) { die "giving up after 4 unsuccessful attempts to create lock file"; } Instead of calling "unlock(lockfile)", the "releaselocks()" function can be called. It removes any leftover locks, which is useful when several different locks are used. Another possible use is to call it in an END code block: END { # In case we bail out, while holding a lock. INN::Utils::Shlock::releaselocks(); } INTERFACE
lock(lockfile) Tries to create a lock file named lockfile. This function returns 1 on success, 0 on failure. lock(lockfile, tries) Tries to create a lock file named lockfile. If it fails, locking attempts are repeated once every 2 seconds for at most tries times (including the first unsuccessful attempt). This function returns 1 on success, 0 on failure. lock(lockfile, tries, delay) Tries to create a lock file named lockfile. If it fails, locking attempts are repeated once every delay seconds for at most tries times (including the first unsuccessful attempt). Note that "lock(lockfile)" is equivalent to "lock(lockfile, 1, 2)". This function returns 1 on success, 0 on failure. releaselocks() Removes all the lock files previously created by calling the "lock(lockfile)" function. This function returns the number of removed lock files. unlock(lockfile) Removes the file named lockfile. This function returns 1 on success, 0 on failure. HISTORY
Documentation written by Julien Elie for InterNetNews. $Id: Shlock.pm.in 9409 2012-05-28 18:43:20Z iulius $ SEE ALSO
perl(1), shlock(1). INN 2.5.3 2012-06-15 INN::Utils::Shlock(3pm)
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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. How- ever, 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 current process id (PID) 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, lockfile-remove, lockfile-touch, and lockfile-check. -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 incre- ments) 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> 0.1.12 2008-02-10 lockfile-progs(1)