# S.Chudley (www.chudley.me) : Lock a file
use Fcntl qw (:flock);
my $file = $ARGV[0];
if (! -f $file) { print "Can't find '$file'\n"; exit(1); }
open(FILE, ">>$file");
flock(FILE, 2);
print "Type something and hit enter to unlock: ";
<STDIN>;
close(FILE);