Shell Programming and Scripting

I am trying to write a bash script to pull out a variable from a dynamically generated "launch.rdp" remote desktop file, and then open rdesktop with that variable. Here's what I have so far:

Code:

#!/bin/bash

rdpfile="$1"

resolution=1024x768
server=$(cat launch.rdp | sed -n "21p" | sed 's/^.\{30\}//g')

/usr/bin/rdesktop -d Domain -g "$resolution" "$server"

sed is pulling out the hostname of the server from the launch.rdp file, and stripping it down to only the address. The script does work, however I'm wanting to get this to work when opening from Mozilla; I.E open with. Any help is appreciated, thank you.