Mod rewrite for replicated wordpress site - .htaccess

Question

I'm trying to direct all traffic to the homepage only to a php script called go.php that gets a variable from the URL.
If someone visits domain.com/username go.php gets the username, looks up their information, saves the information to a session and then redirects to index.php and displays a modified version of the homepage (same domain) that has the retrieved information. Everything works except the mod rewrite part.
I tried the following and am not sure what I am doing wrong:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteRule ^/$ go.php?id=$1 [QSA]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
My logic was that if a request is to index.php it should be allowed, to prevent looping.
If the request is to the homepage it will go to go.php?id=username and the that script will redirect to index.php and trigger the prior mod rewrite rule to prevent looping.
Otherwise, it will do the regular redirect to index.php if the directory or filename doesn't exist.
Any thoughts on how to fix this?

Answer 1

I think this is what you mean:
RewriteRule ^(.*)$ go.php?id=$1 [QSA]
Explanation:
I'm looking at the ^/$ in the regular expression in the go.php rewrite rule. I've tested that and it appears to be an impossible match in that situation. One might be wanting to capture requests for root. But the forward slash is not passed to this portion of the RewriteRule for root. so a call for root (only) is ^$. And there's also no capturing parenthesis to feed the $1 you have appended to go.php?id=$1.