From the doc: 'PHP Shell is a shell wrapped in a PHP script. It's a tool you can use to execute arbiritary shell-commands or browse the filesystem on your remote webserver. This replaces, to a degree, a normal telnet-connection. You can use it for transferring your site as a compressed file, and then unpack it on the webserver, administration and maintenance of your website using commands like ps, free, du, df etc...'