FAQ Title: Defining a class if a string is found in a file
Keywords: define class string file
Classes: any
Section:  Classes and variables

If you want to define a class based on finding a string inside a file,
then do NOT use 'editfiles', as it will define classes only if some
editing took place on that file.

What you have to do is to use 'ReturnsZero', but the tricky part is to
use it properly, here is the format:

<pre>
classes:
   class_you_want_to_define = ( ReturnsZero(/bin/sh -c '/bin/grep "STRING TO LOOK FOR" /file/to/look/in > /dev/null 2>&1') )
</pre>

Pay special attention to the use of single quotes, double quotes and
the redirection of the stdout and stderr.