I need to change my monitor's gamma settings permanently to the value of 0.7. I've tried using xgamma for this, but the thing is I have to execute this command everytime I start my laptop. Also, the gamma settings seem to revert to their original values (1.0) if something significant happens - when I copy/delete something, when I play media from my external hard disk, etc.

I tried making a custom script which reads like:

#!/bin/bash

xgamma -gamma 0.7

Saved it as gammasettings.sh, put it up into my list of start-up applications; but it fails to work for some reason.

Changing these settings again and again is a really cumbersome. Is there a way to make these changes permanent (edit any .conf file or something)?