Environment variables are key-value pairs used by operating systems to store configuration settings and system information. They are essential for customizing the behavior of software applications and the shell environment. On macOS, environment variables play a crucial role in defining paths, user preferences, and other system-wide settings. Understanding how to manage these variables can enhance your productivity and streamline your development workflow.

In this article, we will explore how to set, modify, and remove environment variables on macOS. We will provide practical examples and commands to help you manage these variables effectively.

Examples:

1. Viewing Current Environment Variables: To view the current environment variables, you can use the printenv command in the Terminal.

   printenv

2. Setting Environment Variables Temporarily: To set an environment variable temporarily for the current session, use the export command.

   export MY_VARIABLE="my_value"

   This variable will be available until you close the Terminal session.

3. Setting Environment Variables Permanently: To set environment variables permanently, you need to add them to your shell configuration file. For the default shell (zsh) on macOS, you can edit the ~/.zshrc file.

   nano ~/.zshrc

   Add the following line to set your environment variable:

   export MY_VARIABLE="my_value"

   Save the file and apply the changes by sourcing the file:

   source ~/.zshrc

4. Modifying Existing Environment Variables: To modify an existing environment variable, you can use the export command with the new value.

   export PATH="/new/path:$PATH"

   This example prepends /new/path to the existing PATH variable.

5. Removing Environment Variables: To unset or remove an environment variable, use the unset command.

   unset MY_VARIABLE

6. Using Environment Variables in Scripts: You can also use environment variables in shell scripts. Here is an example script that prints the value of an environment variable:

   #!/bin/zsh
   echo "The value of MY_VARIABLE is: $MY_VARIABLE"

   Save the script as example.sh, make it executable, and run it:

   chmod +x example.sh
   ./example.sh