use strict;
use File::Copy;
use Fcntl ':flock'; # import LOCK_* constants
my $status_file = "/tmp/flocktest";
my $semaphore   = "/tmp/flocktest.sem";

open(SEM,">$semaphore") || die "Can't open file";
flock(SEM, LOCK_EX) || die "Can't lock file";

copy($status_file,"/tmp/foo");

unlink $semaphore; # only on unix
close SEM;