Apache Reference: mod_alias, RedirectMatch

RedirectMatch

Redirect URL via Regular Expression Match
Syntax: RedirectMatch [status] url-pattern [redirect-url]
Example: RedirectMatch ^/(a.+)$ http://foo.dom/$1
Since: Apache 1.3

This directive is similar to AliasMatch, except that the result is an absolute URL to an external resource instead of a local file system path.