Extracting/Removing part of a URI

e.g.

[root@ve11a:Active:Changes Pending] config  tmsh list ltm virtual bar
ltm virtual bar {
    destination 172.28.20.111:80
    ip-protocol tcp
    mask 255.255.255.255
    pool foo
    profiles {
        http { }
        tcp { }
    }
    rules {
        myrule
    }
    source 0.0.0.0/0
    source-address-translation {
        type automap
    }
    vs-index 23
}
[root@ve11a:Active:Changes Pending] config  tmsh list ltm rule myrule
ltm rule myrule {
    when HTTP_REQUEST {
  if { [HTTP::host] equals "originalurl.com" } {
    if { [HTTP::path] starts_with "/pages/index.htm/" } {
      HTTP::respond 301 noserver Location "http://newurl.com[string map {/pages/index.htm/ /} [HTTP::uri]]"
    }
  }
}
}

[root@ve11a:Active:Changes Pending] config  curl -I http://172.28.20.111/pages/index.htm/2013/08/15/mypost -H "Host: originalurl.com"
HTTP/1.0 301 Moved Permanently
Location: http://newurl.com/2013/08/15/mypost
Connection: Keep-Alive
Content-Length: 0