Thanks for your reply, jayant.
I found the ideal software by 'interactivetools.com' (http://www.interactivetools.com) called, 'Search Engine'.
I purchased it. It's great! It will find lines of code VERBATIM!!! If you're looking for e.g. all of files where 'file.php' is called, it will list them. If you're looking for where 'fcn()' is used, it will list all of the files. You don't have to deal with 'escaping' characters or anything! Just add 'php' (or cgi, etc.) in the list of file types in the admin area and it will search them!
Because the search is performed via a browser, you can't click on the found file(s) to see the code of course, but who cares! I can click on the file in my ftp program and load the file in my editor just as easily!
Their 'LIVE' support is the ULTIMATE!!!! See their website for details.
I strongly recommend putting it in a password-protected subdir if you use it this way. I store it outside of my cgi-bin folder and use an .htaccess file that contains the line, 'Options +ExecCGI' (Unix) so it acts as if it is an executable in the cgi-bin folder.
For any coder, this should be a 'MUST HAVE' COOL software program! 🆒
Take care and thanks again!