So I am trying to figure out how to set up a router that can set up site hyperlinks that work with a mod_rewrite situation. I really like PATH_INFO for this as I can use this for apps in subdirs (testing environment for example). This way, you can use http://domain.com/controller/action/1 and still have the fallback url working: http://domain.com/index.php/controller/action/1.

If you place the following code in your htaccess, you can enjoy this technique.

#Force Path info in PHP, gets overridden in RewriteRule.
SetEnvIf Request_URI "^/?" PATH_INFO=/
# Mod Rewrite is off by default.
SetEnv MOD_REWRITE 0

<IfModule mod_rewrite.c>

    # Update environment variable with some info. 
    SetEnv MOD_REWRITE 1
    RewriteEngine On

    # Webroot directory relative to index.php
    RewriteBase /

    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_URI} !^/?(robots\.txt|favicon\.ico|index.php)$
    RewriteRule ^(.*)$ index.php/$1 [QSA,L]
</IfModule>

How does it work?

This way, you can use the following logic in your code to generate a correct url.

1. Construct a variable to prepend:
   1. Take the directory name of the SCRIPT_NAME environment variable if the MOD_REWRITE environment variable is 1…
   2. … Or take just the SCRIPT_NAME environment variable.
2. Add a trailing slash if missing.
3. Add the url to a page you want or use the PATH_INFO environment variable for the current page (canonical links).