use strict;
use warnings;

my $html = <<END_HTML;
Blah blah blah
Web: http://www.example.com
info.example.com
Web: http://info.example.com/
And another
Web site: http://another.example.com/ (doesn't always work)
Nice blog here: http://blog.example.com/niceblog/
END_HTML

my $target = <<END_HTML;
Blah blah blah
Web: <a href="http://www.example.com">www.example.com</a>
job.example.com
Web: <a href="http://info.example.com/">info.example.com</a>
And another
Web site: <a href="http://another.example.com/">another.example.com</a> (doesn't always work)
Nice blog here: <a href="http://blog.example.com/niceblog/">blog.example.com</a>
END_HTML

use Test::More tests => 1;

$html =~ s{(http://(\S+)(?:/\S*)?)}{<a href="$1">$2</a>}g;
is($html, $target);