I am looking for a web interface for shell commands or shell scripts.
Does anyone know of any exexisting php scripts which would solve this
requirement?

PHP form accepts input from a user, then passes these as arguments to
a configurable shell script or OS command. I would like for the
output generated from the shell script/command shall be displayed in a
new javascript window once the form is submitted. Optimally a user
should not not be able to make the program run more than once from
within the javascript window by reloading the window. program
execution shall only be caused by submitting the original form.

-Inet