Exporting DISPLAY variable not working

Question

I am able to assign the DISPLAY variable by running the command line:

export DISPLAY=:2
echo $DISPLAY (returns 2)
hostname (returns opt2)

In my #!/bin/bash script using the same command:

echo $DISPLAY (returns 2)
export DISPLAY=:3 
echo $DISPLAY (returns 3)
hostname (returns opt2)

BUT, when I do echo $DISPLAY after the script is finished I still get "2" as the DISPLAY variable; in other words, the script failed to reassign the DISPLAY variable from "2" to "3".

If I run my bash script a second (third, fourth....) time, I always get:

echo $DISPLAY (returns 2)
export DISPLAY=:3
echo $DISPLAY (returns 3)
hostname (returns opt2)

So, although the script says it assigned the DISPLAY variable to "3", it does not!

How do I make my bash script assign the DISPLAY variable?

Answer 1

Exporting variables only affects subshells. You cannot affect parent shells this way. If you want your script to be able to modify variables in the current shell then you must source it.

. ./some_script.sh