What Are Environment Variables in Linux? Everything You Need to Know
As a Linux user, you might frequently come across the term Environment Variables. If you’re curious what they are and how they work, then you’re in the right place. Environment Variables are an essential component of the Linux operating system as they provide a way to customize the environment for various applications and processes.
An environment variable is a dynamic value that can provide information about the system environment, user preferences, and application settings. When an application starts, it checks for the values of environment variables that are defined for the user or the system.
Environment variables are usually named in all-uppercase letters and are distinguished from regular variables by their prefix “export.” Users can define environment variables in various ways, including:
1. Command-line arguments – Variables can be defined and passed as command-line arguments when executing a program.
2. Shell scripts – Users can create a shell script to define and export variables before running an application.
3. In the .bashrc file – This file is a shell script that gets executed whenever a user logs in. Users can define and export variables in this file.
4. In startup scripts – Environment variables can also be defined in system-wide startup scripts such as /etc/profile, which is executed whenever a user logs in.
Some common environment variables used in Linux are:
1. PATH – This variable specifies the directories in which the system should search for executable files.
2. HOME – This variable defines the home directory of the active user.
3. LANG – This variable specifies the language and locale settings for applications.
4. PS1 – This variable defines the prompt string for the command line interpreter.
5. LD_LIBRARY_PATH – This variable specifies the directories in which the system should search for shared libraries.
6. DISPLAY – This variable specifies the display device that a graphical application should use.
In summary, Environmental Variables are an essential aspect of Linux. They are dynamic values that provide information about the environment to applications and processes. Users can define them in several ways, including command-line arguments, shell scripts, .bashrc files, and startup scripts. Knowing how to use these variables can help users customize their Linux environment and improve their experience with the operating system.