lock.pl

#!/usr/bin/perl -w
use strict;
use Fcntl qw(:DEFAULT :flock );
use Getopt::Std;

sub usage {
        print <<USAGE
Usage:
        SCRIPT.pl -f LOCKFILE

        -l:     The Filename which you wish to lock
USAGE
;
        exit(0);
}

my %options;

getopts("luhf:",\%options);

usage() if $options{h};
usage() unless defined $options{f};

sysopen( FD, "options{f}", O_RDWR|O_EXCL, 0755)
        or die("Cannot open $options{f}: $!\n" );

unless ( flock ( FD, LOCK_EX | LOCK_NB ) ) {
    local $| = 1;
    print "Waiting for lock on filename...";
    flock ( FD, LOCK_SH ) or die ( "Can't lock file: $!\n" );
    print "\n";
} ## end unless ( flock ( FD, LOCK_EX...
print "Received it! Hit Enter to release it...";
my $r = <>;
close ( FD );

exit( 0 );