mod_rewrite - rule according to url path

Question

I am pretty weak at regex, and I need help with a mod_rewrite rule that does the following:

1. If the url is just the domain name: xyz.com -> go to index.php on directory a like so xyz.com/a/index.php
2. If the url includes a path: xyz.com/abcde -> go to index.php on directory b and change the path to a param like so: xyz.com/b/index.php?id=abcde

Both directories a and b are under the same root directory of course.

I managed to do number 2, but I have no idea how to include rule 1.

Answer 1

You can use the following :

RewriteEngine on
#--if url is just the domain name--#
#--rewrite to /a/index.php--#
RewriteRule ^$ /a/index.php [NC,L]

#--if it contains path--#
#--rewrite to /b/index.php?id=path
RewriteRule ^((?!b).+)$ /b/index.php?id=$1 [NC,L]