ISR Computing -

Exclusive file lock in Perl

Many times we need to lock a file for an exclusive lock. e.g you may want to prevent running script simultaneously by different users. Below is an example how to lock a file.

#!/usr/bin/perl
# locktest - file lock example  
use strict; 
use warnings; 
use diagnostics; 
use FileHandle; 
use Fcntl qw(:flock);
open SELF, ">> $0" or die("Unable to lock the file"); 
flock(SELF, LOCK_EX) or die "Cannot lock - $!";   
# Exclusive lock print "Locking...\n"; 
sleep(60); close SELF; 
print "Unlocked...\n"; 
exit 0;
 

Now, log in and run “locktest”. At the same time, log in as a different user account and run the same script. You will see that it will not lock until the other script finishes.