You have to edit three files to set a permanent environment variable as follow:
-
~/.bashrc
When you open any terminal window this file will be run. Therefore, if you wish to have a permanent environment variable in all of your terminal windows you have to add the following line at the end of this file:
export DISPLAY=0 -
~/.profile
Same as bashrc you have to put the mentioned command line at the end of this file to have your environment variable in the every login of your OS.
-
/etc/environment
If you want your environment variable in every windows or application ( not just terminal window ) you have to edit this file. Add the following command at the end of this file:
DISPLAY=0
Note that in this file you do not have to write export command
Normally you have to restart your computer to apply this changes. But you can apply changes in bashrc and profile by these commands:
$ source ~/.bashrc$ source ~/.profile
But for /etc/environment you have no choice but restarting ( as far as I know )
* A Simple Solution
I’ve written a simple script for this procedures to do all those work. You just have to set name and value of your environment variable.
#!/bin/bash
echo "Enter variable name: "
read variable_name
echo "Enter variable value: "
read variable_value
echo "adding " $variable_name " to environment variables: " $variable_value
echo "export "$variable_name"="$variable_value>>~/.bashrc
echo $variable_name"="$variable_value>>~/.profile
echo $variable_name"="$variable_value>>/etc/environment
source ~/.bashrc
source ~/.profile
echo "do you want to restart your computer to apply changes in /etc/environment file? yes(y)no(n)"
read restart
case $restart in
y) sudo shutdown -r 0;;
n) echo "don't forget to restart your computer manually";;
esac
exit
Save this lines in a shfile then make it executable and just run it!