Redirect URI to different URL and only keep query strings

Is the first part of the URI static, or do you need to remove the first part of the URI no matter what it is? If the former, a simple string map should cover it:

when HTTP_REQUEST {
    if { [string tolower [HTTP::uri]] starts_with "/hello" } {
        set newuri [string map {"/hello" ""} [HTTP::uri]]
        if { $newuri eq "" } { set newuri "/" }
        HTTP::redirect "http://[HTTP::host]$newuri"
    }
}