printing a php file as a text file

How would I go outputting my PHP file as a text file -- for example, I have
a set of scripts that I plan to release to the public and would like to make
this script viewable through PHP without having to call a text file. I know
I have seen this somewhere and I'm wondering if any of you guys know how to
do this..

In case the above was confusing, I want to have a link that will allow the
user to view the source code (and have it print out the code without
executing it).

Chris