!/usr/bin/perl

use strict;
use Fcntl;

my($pack);


open(FILE,">a");
$pack = pack('s s l l l', &F_WRLCK, 0, 0, 1, 0);
print(fcntl(FILE, &F_SETLKW, $pack) . "\n");
sleep(20);
$pack = pack('s s l l l', &F_UNLCK, 0, 0, 1, 0);
print(fcntl(FILE, &F_SETLKW, $pack) . "\n");
close(FILE);