Capture a group in RewriteCond

Question

I have this rule:

RewriteCond %{QUERY_STRING} size=(\d+)

and want to capture (\d+) for later use in RewriteRule or RewriteCond. Something like this:

RewriteCond %{QUERY_STRING} size=(\d+)
RewriteCond $1 <1024 ## that $1 refers to (\d+)

How can I achieve that?

Answer 1

You need to use the % backreferences:

RewriteCond %{QUERY_STRING} size=(\d+)
RewriteCond ^ /%1 [L]

The %1 backreferences a previously captured group in a rewrite cond.