Select Code to Download

use strict;
use warnings;
...
print localtime().": $$'s flock obtained\n";
sleep(5);
print localtime().": $$ ends\n";

$ for q in 1 2 3 4 ; do perl 807067.pl & done
Fri Nov 13 17:21:04 2009: 20079's flock attempt starts
...
Fri Nov 13 17:21:19 2009: 20082 ends
Fri Nov 13 17:21:19 2009: 20080's flock obtained
Fri Nov 13 17:21:24 2009: 20080 ends

Fri Nov 13 17:26:42 2009: 20116's flock attempt starts
Fri Nov 13 17:26:42 2009: 20116's flock obtained
...
flock: Resource temporarily unavailable
Fri Nov 13 17:26:42 2009: 20119's flock attempt starts
flock: Resource temporarily unavailable

use Errno qw( EWOULDBLOCK );

...
else {
    some error
}