I need to have both installed and running on the same server instance for a dev environment.
They both need to handle the .php extension, I have read that this can be done by .htaccess set up but have know idea how to do the actual installation.
Google/Serverfault searches came up dry. Any information/resource links would be useful. Or if it has been asked as I am sure it would be rather common, please redirect me to the dupe.
You can do it by building two apache modules with different types: "application/x-httpd-php4" and "application/x-httpd-php5". Load them both into apache, and specify in httpf.conf:
AddType application/x-httpd-php4 .php4
AddType application/x-httpd-php5 .php5
AddType application/x-httpd-php5 .php # the default
Now you'll have to use ".php4" extension for files to be handled with PHP4, and ".php5" for PHP5. ".php" files are also processes with PHP5 by default.
UPD: In order to have some folders executing PHP scripts with PHP4 module you can override the default PHP5 with PHP4. Just use this in .htaccess:
AddType application/x-httpd-php4 .php
With php in CGI mode you'll be able to use .htaccess configuration. Build both PHP versions in CGI mode, place the executables into cgi-bin folder, and try the following in .htaccess:
AddType application/cgi-php php
Action application/cgi-php /cgi-bin/php4.cgi
However, this way is much worse in the means of performance.
.htaccess is ok :) It's a drawback in the very principle of CGI: every time a page is opened Apache launches the cgi executable and handles php script with it. Launching a process every time is much slower than having a built-in module. That's why FCGI was created: it launches cgi scripts and handles all scripts with several processes that, once launched, don't stop :) You can try CGI: it's rather slow, but still acceptable in some cases.