This script is intended to be dropped in to a web server to give a simple directory index.
It targets PHP 5.2.
Files starting with . and files called index.php are excluded from listings.
On Apache servers, if overrides are allowed,
it can apply also to child directories
by adding a .htaccess file in the same directory as this script
with the following contents:
DirectoryIndex /path/to/index.php
This path should start from the document root.
Icons are expected to be found in /usr/share/icons/gnome/32x32,
which on Ubuntu comes from the package gnome-icon-theme.
It's likely most or all GNOME icon themes follow the same naming scheme,
so there are probably a lot of available drop-in replacements.