How to create a new environment variable in Linux?

Introduction

This tutorial will guide you through the process of creating a new environment variable in the Linux operating system. Environment variables are an essential part of the Linux ecosystem, allowing you to customize system settings and enhance your programming experience. By the end of this article, you will have a solid understanding of how to create, manage, and apply new environment variables in your Linux environment.

Skills Graph

Understanding Environment Variables

Environment variables are a fundamental concept in Linux operating systems. They are named values that provide information about the user's environment, system configuration, or application settings. These variables are accessible to all running processes and can be used to customize the behavior of programs and scripts.

Environment variables are typically defined at the system level or the user level. System-level variables are available to all users and processes, while user-level variables are specific to the current user.

Some common use cases for environment variables include:

1. Specifying Paths: Environment variables like PATH are used to specify the directories where the system should search for executable files.
2. Configuring Applications: Environment variables can be used to set configuration options for applications, such as the EDITOR variable to specify the default text editor.
3. Storing Sensitive Information: Environment variables can be used to store sensitive information, such as API keys or database connection strings, without hardcoding them in scripts or configuration files.

To view the current environment variables, you can use the env or printenv commands in the Linux terminal:

env
printenv

This will display a list of all the environment variables currently defined in the system.

Creating a New Environment Variable

To create a new environment variable in Linux, you can use the following methods:

Temporary Environment Variable

To create a temporary environment variable that will only exist for the current shell session, you can use the export command:

export MY_VARIABLE="my_value"

This will create a new environment variable named MY_VARIABLE with the value my_value. You can then use this variable in your current shell session.

Persistent Environment Variable

To create a persistent environment variable that will be available across all shell sessions, you need to modify the appropriate configuration file. The most common configuration files for this purpose are:

• ~/.bashrc (for Bash shell)
• ~/.zshrc (for Zsh shell)

Add the following line to the appropriate configuration file:

export MY_VARIABLE="my_value"

After saving the file, the new environment variable will be available for all subsequent shell sessions.

You can also use the export command within the configuration file to achieve the same result:

export MY_VARIABLE="my_value"

To make the changes take effect immediately, you can either log out and log back in or run the following command:

source ~/.bashrc ## or ~/.zshrc for Zsh

This will reload the configuration file and make the new environment variable available.

Applying the New Environment Variable

Once you have created a new environment variable, you can use it in your scripts, commands, or applications. Here are a few ways to apply the new environment variable:

Accessing the Variable

To access the value of the environment variable, you can use the $ symbol followed by the variable name. For example, if you created a variable named MY_VARIABLE, you can access its value like this:

echo $MY_VARIABLE

This will output the value of the MY_VARIABLE environment variable.

Using the Variable in Commands

You can also use the environment variable within commands or scripts. For example, you can use the variable in a cd command to change the current working directory:

cd $MY_VARIABLE

This will change the current directory to the value of the MY_VARIABLE environment variable.

Passing the Variable to Child Processes

When you run a command or script, the environment variables are passed down to any child processes or subshells. This means that the new environment variable will be available to any programs or scripts that are executed from the current shell session.

my_script.sh

In the above example, the my_script.sh script will have access to the MY_VARIABLE environment variable.

Verifying the Variable

To verify that the new environment variable is available and has the correct value, you can use the env or printenv commands:

env | grep MY_VARIABLE
printenv MY_VARIABLE

These commands will display the value of the MY_VARIABLE environment variable.

By understanding how to create and apply new environment variables, you can customize your Linux environment and streamline your workflow.

Summary

In this comprehensive Linux tutorial, you have learned how to create a new environment variable, including understanding the concept of environment variables, the steps to set up a new variable, and how to apply it effectively. Mastering environment variable management is a crucial skill for Linux programmers and system administrators, as it enables you to customize your working environment and streamline your development processes. With the knowledge gained from this tutorial, you can now confidently manage environment variables and take your Linux programming skills to the next level.