#!/usr/bin/perl
use strict;
use File::Basename;
use File::MMagic;

#skip some code here...

my ($name,$path,$suffix) = fileparse($filename);

my $mm = File::MMagic->new('/usr/share/file/magic');
my $mimetype = $mm->checktype_byfilename($name);

print "Content-type: $mimetype\n";
print "Content-Disposition: attachment; filename=\"$name\"\n\n";

#other code goes here to output file...