RewriteEngine URL to php _get arguments - php

Question

On my website I want to internally execute a url like mydomain.com/dir/test as mydomain.com/dir/process.php?arg=test
I already created a htaccess file within the folder "dir", and when I try to access mydomain.com/dir/test, it displays the page of process.php, but when I try to access $_GET["arg"], it does not contain the string test but the string process.php.
My .htaccess:
RewriteEngine On
RewriteRule ^(.*)$ process.php?arg=$1 [L]

Answer 1

Reason for your result is a rewriting loop. You try to stop the rewriting process by using the [L] flag, but as many others you miss understand what that flag actually does. It does not end the rewriting process, but only the current run of that process. In your case the rewriting process starts another run and again rewrites your already rewritten request. In the second run the pattern ^(.*)$ matches what you have rewritten to in the first run, that explains your outcome.
You have two options to solve this.
1) use a condition to prevent the second rewriting run:
RewriteEngine On
RewriteCond %{REQEUEST_URI} !/process\.php$
RewriteRule ^(.*)$ process.php?arg=$1 [L]
2) use the END flag which is provided by newer versions of the apache http server:
RewriteEngine On
RewriteRule ^(.*)$ process.php?arg=$1 [END]
In case you receive an internal server error (http status 500) using that second rule above then chances are that you operate a very old version of the apache http server. You will see a definite hint to an unsupported [END] flag in your http servers error log file in that case.
And a general remark: you should always prefer to place such rules in the http servers host configuration instead of using dynamic configuration files (".htaccess"). Those dynamic configuration files add complexity, are often a cause of unexpected behavior, hard to debug and they really slow down the http server. They are only provided as a last option for situations where you do not have access to the real http servers host configuration (read: really cheap service providers) or for applications insisting on writing their own rules (which is an obvious security nightmare).