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Linux environment variables explained

Bil Al -

Linux environment variables are variables that are set system-wide and are available to all users and processes on the system. They can be used to store information such as the system's hostname, the default editor, and the default path to search for executables.

There are two types of environment variables in Linux: global variables and local variables. Global variables are set system-wide and are available to all users and processes. Local variables are set for a specific user or process and are only available in that context.

To view the current environment variables on your system, you can use the env command. This will display a list of all the environment variables and their values. You can also use the echo command to view the value of a specific environment variable. For example:

echo $PATH

To set an environment variable, you can use the export command. For example:

export MYVAR=value

This will set the environment variable MYVAR to the value value. To set a local environment variable, you can use the set command. For example:

set MYVAR=value

To make an environment variable permanent, you will need to add it to a startup file such as .bashrc or /etc/environment. This will ensure that the variable is set every time you log in or start a new shell.

There are many predefined environment variables in Linux that serve important functions. Some examples include:

  • PATH: This variable specifies the directories that should be searched for executables. When you type a command in the terminal, the system searches the directories listed in PATH to find the executable.
  • HOME: This variable specifies the home directory of the current user. It is often used as a reference point for other paths and variables.
  • SHELL: This variable specifies the default shell for the system.
  • LANG: This variable specifies the default language and character encoding for the system.
  • TERM: This variable specifies the terminal type and capabilities.

Understanding and utilizing environment variables can be a powerful tool in customizing and automating tasks in Linux. They are a core part of the Linux environment and are worth learning about to become a proficient Linux user.