note 45464 added to function.flock

Like a user already noted, most Linux kernels (at least the Redhat ones) will return false, even if you locked the file. This is because the lock is only ADVISORY (you can check that in /proc/locks). What you have to do there is to evalute the 3rd parameter of flock(), $eWouldBlock. See for an example below. Note however that if you lock the file in non blocking mode, flock() will work as expected (and blocks the script). <?php $fp = fopen( "/var/lock/process.pid", "a" ); if ( !$fp || !flock($fp,LOCK_EX|LOCK_NB,$eWouldBlock) || $eWouldBlock ) { fputs( STDERR, "Failed to acquire lock!\n" ); exit; } // do your work here fclose( $fp ); unlink( "/var/lock/process.pid" ); ?> ---- Manual Page -- http://www.php.net/manual/en/function.flock.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+45464 Delete -- http://master.php.net/manage/user-notes.php?action=delete+45464&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+45464&report=yes Search -- http://master.php.net/manage/user-notes.php