Environment Variables
An environment variable is a user-defined value that can affect the way running processes behave on a computer. In Linux, we can check them with the command env
and identify them because they start with the $
symbol.
Some of the most common preset environment variables are:
$PATH
: List of directories for searching executable files or other directories, by default, contains the directories of system applications and installed apps$USER
: The user that is currently logged in$PWD
: Current working directory$HOME
: Home Directory path$$
: Current shell PID$SHELL
: The path to the current shell that determines which command-line interface is being used$TERM
: Indicates the type of terminal to emulate when running the shell$LANG
: Specifies the language and locale settings for the user environment$EDITOR
: The default text editor set for the user$MAIL
: The path to the user's mailbox$DISPLAY
: Used in graphical environments to specify the display server to connect to$HISTSIZE
: Defines the number of commands to remember in the command history for the current user session
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