Environment Variables: Understanding and Using Them

Environment Variables in Linux: Understanding and Using Them

In Linux and other Unix-like operating systems, environment variables are a set of dynamic named values stored within the system that are used by applications running on the operating system. They play a critical role in influencing the behavior of the software on your computer. In this blog, we will delve into what environment variables are, where they are used, and how you can manage them effectively in Bash, the popular command-line interface for Linux. Additionally, we will explore how to install necessary tools with different package managers like apt, dnf, and zypper.

What are Environment Variables?

Environment variables are used to store information about the environment in which the operating system runs. This information can include the location of executable files, home directories, system libraries, and preferences like the default editor or browser. Variables such as PATH, HOME, USER, and SHELL are commonly used across different Linux distributions.

Commonly Used Environment Variables

• PATH: Maintains a list of directories where executable files are located. Often modified to add new software tools to the shell’s search path.

• HOME: Indicates the current user's home directory.

• USER: Keeps track of the current logged-in user.

• SHELL: Specifies the path to the default user shell.

• EDITOR: Determines the default text editor, which is used by some commands for text editing.

Viewing Environment Variables

To see the value of a specific environment variable in Bash, you can use the echo command. For example:

echo $HOME

To print all environment variables, use the env command or printenv:

env

Setting Environment Variables

You can set environment variables using the export command in Bash. For instance, if you want to set EDITOR to use vim, you would do:

export EDITOR=vim

These changes will apply only to the current session. To make them permanent, add such export commands to your shell initialization files like .bashrc or .bash_profile.

Modifying the PATH Variable

To add a new directory to your PATH, use the export command appending the new directory:

export PATH=$PATH:/path/to/directory

Remember, this change is temporary unless added to a shell initialization file.

Setting and Unsetting Variables

To unset an environment variable, which means removing it from the environment, use:

unset VARIABLE_NAME

Installing Packages across Different Linux Distributions

To manage and install packages you might need to add to your environment, Linux offers multiple package managers. Here’s how to use them:

1. APT (for Debian-based distributions):

   • Update your package list: sudo apt update
   • Install a package: sudo apt install package_name

2. DNF (for Fedora and RHEL-based distributions):

   • Update your package list: sudo dnf makecache
   • Install a package: sudo dnf install package_name

3. Zypper (for openSUSE):

   • Refresh the repository: sudo zypper refresh
   • Install a package: sudo zypper install package_name

Conclusion

Understanding environment variables and knowing how to manipulate them is crucial for effectively using Linux systems. By managing environment variables, you can customise the workings of software applications, and streamline your workflow. Whether adjusting the PATH variable or setting default editors, knowing your way around these settings in Bash provides you with a powerful tool in your system administration arsenal.

Hopefully, this guide not only explained the basics of environment variables in Linux but also assisted you in understanding how to manage them using different system package managers. The tasks may seem daunting at first, but with practice, they will become second nature. Happy computing!