From what you say, I think pasting it into xterm makes xterm try to run the file as though it was a shell script. In windows terms this is like changing the extension of an ini file to .bat and trying to execute it.. Won't work.

What you need to do is take a backup copy of your existing file, then replace it with your altered version. In xterm, you can do this as follows, supposing your new version is at /home/user/MyDocs/rx-51.

You might need to be root to do this, or maybe using sudo cp instead of cp would work, not sure since I did this as root myself.

Once you've copied the file, again in xterm run:

to activate your new config.

Again, best to think of the rx-51 as (in Windows terms) an ini file, so you need to restart the subsystem that uses it by using the setxkbmap command as above.

If you're not sure what you're doing, probably best to find definitive instructions before you go ahead messing about with xterm, sudo and root access, though, and maybe learn a bit about that environment.

Personally, when I've been doing this sort of thing, I've ssh'd in as root so that if things break I have more chance of being able to fix it without being dependent on things I might be breaking (like the keyboard config )