Disabling keys in Ubuntu permanently

Question

I managed to disable a key by following Disable key on keyboard.

Based on drs305 you can disable it permanently by adding the command to the start application.

And I did a work around:

scripts.sh

#!/bin/bash

xmodmap -e 'keycode 64=' // note that this will disable Atl_L key

I checked the Allow executing file as program checkbox in the *Properties → Permission tab. Then after executing the file the command works well. But after including it in the Startup Applications and restarting the computer it doesn't seem to work.

I purposed to do this to make the Alt + L key permanently disable in start up, but nothing work.