htaccess with url rewriting not working - php

Question

This is my htaccess code:
RewriteEngine On
RewriteRule ^/typo3$ - [L] RewriteRule ^/typo3/.*$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-l
RewriteRule .* /index.php
RewriteRule ^/([a-zA-Z0-9_-]+)$ http://www.example.com/index.php?id=82&user=$1 [L,R=301]
Obviously I want this URL:
www.example.com/username
to be translated to http://www.example.com/index.php?id=82&user=username
This does not work however.. (this code results in the htaccess not working at all and getting a Page not found error.
If I change the ]+$ for a ]+? the code does work, but not like I want:
RewriteEngine On
RewriteRule ^/typo3$ - [L] RewriteRule ^/typo3/.*$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-l
RewriteRule .* /index.php
RewriteRule ^/([a-zA-Z0-9_-]+)? http://www.example.com/index.php?id=82&user=$1 [L,R=301]
Results in the URL being rewritten/redirected to http://www.example.com/index.php?id=82&user=index ... Exactly like that, so with user=index.
Now, if I remove the RewriteRule .* /index.php line, the htaccess again doesn't work at all anymore, resulting in a Page not found error...
I've spent days and days on figuring this out but I'm absolutely clueless..
So, I just want www.example.com/username to redirect to http://www.example.com/index.php?id=82&user=username

Answer 1

There are several issues here.
Inside a .htaccess file, patterns are matched "against the filesystem path, after removing the prefix". This means, you will have no leading slash as in /typo3 or ^/([a-zA-Z0-9_-]+)?
The pattern ([a-zA-Z0-9_-]+)? matches also an empty request, because of the trailing ?. I guess, this is not what you intended.
Rules are processed in sequence, unless you do a redirect [R] or add an [L] flag. This is the reason why first the request is rewritten to index.php and then in the next rule index is recognized as the user and again rewritten to .../index.php?id=82&user=index
Which leads to the next problem between the patterns .* and ([a-zA-Z0-9_-]+). .* recognizes all requests, including every user. So there is no way to distinguish between a user and any other request.
To rewrite usernames, you could try
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([a-zA-Z0-9_-]+) http://www.example.com/index.php?id=82&user=$1 [L]
This means, if the request doesn't correspond to an existing file !-f or directory !-d, then presume it's a username and rewrite to index.php?....
If you don't want a redirect, leave out the host name
RewriteRule ^([a-zA-Z0-9_-]+) /index.php?id=82&user=$1 [L]