http://www.perlmonks.org?node_id=1033391


in reply to Check for another running instance of the same program

LanX ++

There are many ways to ensure single instance of perl program is running. PID files are the traditional way to do it. we can also hold a lock on a file,for example the program itself. This small piece of code will do the trick:

use Fcntl ':flock'; open my $self, '<', $0 or die "Couldn't open self: $!"; flock $self, LOCK_EX | LOCK_NB or croak "This script is already runnin +g";

One advantage over PID files is that files automatically get unlocked when the program exits. It is much easier to implement in a reliable way.


All is well