How to set an environment variable?

To set an environment variable in a shell, you can use the export command. Here’s how to do it:

Temporary Environment Variable

This variable will only last for the duration of the current shell session.

1. Open your terminal.

2. Use the export command to set the variable:

   export MY_VARIABLE="my_value"

3. You can verify that it has been set by using:

   echo $MY_VARIABLE

Permanent Environment Variable

To make the variable persistent across sessions, you need to add it to your shell's configuration file.

For Bash:

1. Open the .bashrc file:

   nano ~/.bashrc

2. Add the following line at the end of the file:

   export MY_VARIABLE="my_value"

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

   source ~/.bashrc

For Zsh:

1. Open the .zshrc file:

   nano ~/.zshrc

2. Add the following line at the end of the file:

   export MY_VARIABLE="my_value"

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

   source ~/.zshrc

System-wide Environment Variable

To set an environment variable that is available to all users:

1. Open or create a file in /etc/profile.d/:

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

2. Add the following line:

   export MY_VARIABLE="my_value"

3. Save and exit the editor.

After following these steps, the environment variable will be set and available in your shell sessions.