Re: Easiest way to protect process from duplication.

use Fcntl ':flock';

open my $fh, "+<", $0 or exit;
exit unless flock $0, LOCK_EX | LOCK_NB;
[download]

Note that depending on your OS and how you call the program, a second open may fail (and then, the flock isn't necessary).

Comment on Re: Easiest way to protect process from duplication. Download Code

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Re^2: Easiest way to protect process from duplication. by gnosti (Chaplain) on Jan 23, 2012 at 05:52 UTC
Here's a variation that uses the __DATA__ handle. `use Fcntl qw(LOCK_EX LOCK_NB); die "Another instance is already running" unless flock DATA, LOCK_EX\|L +OCK_NB;` [download]	[reply] [d/l]
Re^3: Easiest way to protect process from duplication. by JavaFan (Canon) on Jan 23, 2012 at 07:47 UTC
That actually requires a `__DATA__` (or `__END__`) token to be present.	[reply] [d/l] [select]
Re^4: Easiest way to protect process from duplication. by kazak (Beadle) on Jan 24, 2012 at 13:38 UTC
Thank you too. BTW __END__,__DATA__,etc is there any general name for these tokens, (like "Labeled blocks", "builtins",...)? I'm newbie in perl so I just wanted to read about this stuff.	[reply]
Re^3: Easiest way to protect process from duplication. by kazak (Beadle) on Jan 24, 2012 at 13:29 UTC
Thank you for your post, that is what I really need.	[reply]
Re^2: Easiest way to protect process from duplication. by kazak (Beadle) on Jan 21, 2012 at 06:16 UTC
Thanks for your attention, everyone. Program supposed to run in a background. (I mean # test.pl &) so is it changing something ?	[reply]
Re^3: Easiest way to protect process from duplication. by JavaFan (Canon) on Jan 21, 2012 at 08:38 UTC
No, why should it?	[reply]