How to make a variable permanent?

To make a shell variable permanent, you need to add it to a shell configuration file that is executed whenever a new shell session starts. Here are the steps to do this:

1. Open the Shell Configuration File: Depending on the shell you are using, you can add the variable to one of the following files:

   • For bash, use ~/.bashrc or ~/.bash_profile.
   • For zsh, use ~/.zshrc.

   You can open the file using a text editor, for example:

   nano ~/.bashrc
   

2. Add the Variable: Add the variable definition at the end of the file. For example:

   export MY_VAR="Hello, Permanent Variable"
   

3. Save and Exit: Save the changes and exit the text editor.

4. Apply the Changes: To apply the changes without restarting the terminal, run:

   source ~/.bashrc
   

   or

   source ~/.bash_profile
   

5. Verify the Variable: You can verify that the variable is set by running:

   echo $MY_VAR
   

   Output:

   Hello, Permanent Variable
   

Now, the variable will be available in all new terminal sessions.