#!/usr/bin/perl -l

# http://perlmonks.org/?node_id=1138025

use strict;
use warnings;

$_ = <<END;
<xml>
<info>
<file>file:/path/to/some/file.mxf</file>
</info>
<info>
<file>file:/path/to/some/file.xml</file>
</info>
</xml>
END

print m{.*<file>file:(.*?\.xml)</file>}s ? $1 : "xml not found";