mod_rewrite doesn't actually... re-write the URL - .htaccess

Question

Basically, I've been trying to make some friendly URL's via .htaccess using mod_rewrite - and I've managed to get it to work... but only with basic stuff like:
RewriteEngine On
RewriteBase /
RewriteRule ^profile.php http://www.google.co.uk [L]
So mod_rewrite works, and I can re-direct to other sites, other files/directories in my server, etc. - but it seems to not work when I use this:
RewriteEngine On
RewriteBase /
RewriteRule ^profile.php?user=$1 ^profile/user/([^/]*)/$ [L]
Any help on this would be great, as I pretty much suck at mod_rewrite, but it's something I need to learn.
Cheers!

Answer 1

Change your [L] to [R,L] to force an actual HTTP redirect. Otherwise it just does the rewriting internally (when possible), which only affects the mapping from the URI to the filesystem. (See the description of the [R] flag at http://httpd.apache.org/docs/current/mod/mod_rewrite.html#rewriteflags.)

Answer 2

Wrong.
## rewriting from to
RewriteRule ^profile.php?user=$1 ^profile/user/([^/]*)/$ [L]
Should be
## rewriting from to
RewriteRule ^profile/user/([^/]+)$ profile.php?user=$1 [L]

Answer 3

Your configuration currently is this:
RewriteEngine On
RewriteBase /
RewriteRule ^profile.php?user=$1 ^profile/user/([^/]*)/$ [L]
In the RewriteRule you swapped the from and to parameters.
Assuming that on your server there is a directory structure like this:
/var/www/htdocs/profile/user/albert
/var/www/htdocs/profile/user/bob
Then you can use the following rule:
RewriteCond ${QUERY_STRING} ^user=(\w+)$
RewriteRule ^profile\.php$ profile/user/%1 [L]
There are some points that you got wrong here:
The request to "/profile.php?user=bob" first gets split into the Request URI and the Query String. Only the Request URI will be used by mod_rewrite. Therefore you have to handle the query string separately.
I restricted the user name to only [A-Za-z0-9_]. If I had allowed all characters, an attacker could easily call /profile.php?user=../../config.php, which would be rewritten to profile/user/../../config.php, and you probably don't want to share that file with the world.
The arguments to the RewriteRule directive are completely different regarding their syntax.
The first argument (the from part) is a regular expression, which usually starts with a caret ^ and ends with a dollar $.
The second argument (the to part) is the replacement, which is almost only a simple string, with only some special features. This string usually doesn't start with a caret, but looks rather like a pathname.