like md5sum utility ;-)

md5.pl

#!/usr/bin/env perl

use 5.010;
use utf8;
use strict;
use warnings;
use Digest::MD5;
use File::Slurp;

say sprintf('%s  %s', digest($_), $_) for @ARGV;

sub digest {
    my $file = shift;

    return unless -f $file;

    my $data = read_file( $file );
    my $ctx = Digest::MD5->new;
    $ctx->add($data);

    return $ctx->hexdigest;
}