htaccess rewrite for subdomain only - .htaccess

Question

I'm trying to rewrite some parameters to beautiful links, but for a subdomain / a folder only. Unfortunately I can't get it to work, maybe also because there are some other rewrites in line before...
Heres my code:
<IfModule mod_rewrite.c>
# NON-WWW TO WWW
RewriteEngine On
RewriteCond %{HTTP_HOST} ^example.com
RewriteRule (.*) http://www.example.com/$1 [R=301,L]
# WORDPRESS-BLOG
Options +FollowSymlinks
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
# REDIRECT FOR SUBDOMAIN
RewriteCond %{HTTP_HOST} ^subdomain.example.com
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^/.]+)(?:/)?$ index.php?cshort=$1 [L]
RewriteRule ^([^/.]+)/([^/.]+)(?:/)?$ /index.php?cshort=$1&cid=$2 [L]
RewriteRule ^([^/.]+)/([^/.]+)/([^/.]+)(?:/.*)?$ /index.php?cshort=$1&cid=$2&step=$3 [L]
</IfModule>
Basically only the last part is the one I want to rewrite to change URLs from something like
http://subdomain.example.com/index.php?cshort=abc&cid=123&step=1 to http://subdomain.example.com/abc/123/1
The other rewriting rules for www.example.com shouldn't get affected. Unfortunately my current codes only does the first two rules for the blog and the www, but nothing happens on the subdomain. What's wrong in my code?

Answer 1

When you say that you want to rewrite from http://subdomain.example.com/index.php?cshort=abc&cid=123&step=1 to http://subdomain.example.com/abc/123/1 you mean that you want the user to enter the pretty URL and to have it serve the full URL in the background, not that you want to redirect from the ugly to the pretty URL, right?
In your RewriteRules, what are you trying to accomplish with "(?:/)?"? As written, that doesn't make any sense to me. If you're just trying to match whether or not the directory path ends with a slash, you can do that as follows:
RewriteRule ^([^/.]+)/?$ index.php?cshort=$1 [L]
EDIT: Additional suggestions:
Move the "Redirect for subdomain" section above the "Wordpress Blog" section. Since the Wordpress rule applies to "everything that's not a real file or directory, regardless of domain" that should go last.
RewriteConds only apply to a single RewriteRule that follows them. For each of the three rules you have listed under "Redirect for subdomain", after updating them per the above suggestion, you need to repeat the two RewriteCond lines in front of the RewriteRule.