How to make variables persistent?

To make shell variables persistent across terminal sessions, you can define them in your shell's configuration file. Here’s how to do it for different shells:

For Bash:

1. Open the .bashrc file in your home directory:

   nano ~/.bashrc

2. Add your variable at the end of the file:

   export MY_VARIABLE="my_value"

3. Save the file and exit the editor.
4. To apply the changes, run:

   source ~/.bashrc

For Zsh:

1. Open the .zshrc file in your home directory:

   nano ~/.zshrc

2. Add your variable at the end of the file:

   export MY_VARIABLE="my_value"

3. Save the file and exit the editor.
4. To apply the changes, run:

   source ~/.zshrc

For System-wide Variables:

1. Edit the /etc/profile file or create a new file in /etc/profile.d/:

   sudo nano /etc/profile.d/my_variables.sh

2. Add your variable:

   export MY_VARIABLE="my_value"

3. Save the file and exit the editor.
4. The changes will take effect for all users after a restart or by sourcing the profile.

By following these steps, your variables will be available in new terminal sessions.