Setting system variables when they wont stick

add_variable.sh

#!/bin/bash

# This is useful for setting variables when they will not stick

echo "Enter variable name: "
read variable_name
echo "Enter variable value: "
read variable_value

echo "adding " $variable_name " to einvironment 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 wanna 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