5 Environment Variables in Linux You Should Know Of

Important Environment Variables In Linux

Environment variables in Linux can be defined as a set of variables which describe the the environment in which an application or program runs. These variables aren’t explicitly defined in a file or stored as such, but are defined when a program is executed.

List of Environment variables in Linux

In this module we will go over some environments which might be of interest to a Linux User and see what each of them signifies.


This variable specifies the user you are logged in as. You can view this is with :

$ echo $USER

Note that this command still gives you your original username even when run with sudo privileges, because even though it is evoked with elevated privileges using sudo, the user remains the same.

$ sudo echo $USER

This can be utilitarian in scenarios when you want to know the user you are logged in as, a common scenario when it comes to CTFs.


This environment variable defines the home directory of our user. It is well known that when we use the following commands, they take us to the user’s home directory:

$ cd


$ cd ~

However, if we want to change the home directory to be some other directory, we can simply change the value of our HOME environment variable with :

$ export HOME=/path/to/directory

Learn more about setting environment variables here.


TERM is one of the environment variables in Linux set by the program that connects with the user logins. It defines the login terminal type. You can get a list of possible values of the TERM variable with :

$ ls /lib/terminfo/x/
x10term       xnuppc+80x30    xnuppc-80x30-m   xnuppc-256x96    xterm+edit      xterm+sm+1002     xterm-basic    xterm-vt220
x68k          xnuppc+90x30    xnuppc-90x30     xnuppc-256x96-m  xterm+indirect  xterm+sm+1003     xterm-bold     xterm-x10mouse
x68k-ite      xnuppc+100x37   xnuppc-90x30-m   xnuppc-b         xterm+kbs       xterm+sm+1005     xterm-color    xterm-x11hilite
x820          xnuppc+112x37   xnuppc-100x37    xnuppc-f         xterm+keypad    xterm+sm+1006     xterm-direct   xterm-x11mouse
x1700         xnuppc+128x40   xnuppc-100x37-m  xnuppc-f2        xterm+noalt     xterm+titlestack  xterm-direct2  xterm-xf86-v32
x1700-lm      xnuppc+128x48   xnuppc-112x37    xnuppc-m         xterm+noapp     xterm+tmux        xterm-hp       xterm-xf86-v33
x1720         xnuppc+144x48   xnuppc-112x37-m  xnuppc-m-b       xterm+osc104    xterm+vt+edit     xterm-kitty    xterm-xf86-v40
x1750         xnuppc+160x64   xnuppc-128x40    xnuppc-m-f       xterm+pc+edit   xterm+x10mouse    xterm-mono     xterm-xf86-v43
xdku          xnuppc+200x64   xnuppc-128x40-m  xnuppc-m-f2      xterm+pcc0      xterm+x11hilite   xterm-new      xterm-xf86-v44
xenix         xnuppc+200x75   xnuppc-128x48    xtalk            xterm+pcc1      xterm+x11mouse    xterm-nic      xterm-xf86-v333
xerox         xnuppc+256x96   xnuppc-128x48-m  xterm            xterm+pcc2      xterm-8bit        xterm-noapp    xterm-xfree86
xerox-lm      xnuppc+b        xnuppc-144x48    xterm+88color    xterm+pcc3      xterm-16color     xterm-old      xterm-xi
xerox820      xnuppc+basic    xnuppc-144x48-m  xterm+256color   xterm+pce2      xterm-24          xterm-pcolor   xterm.js
xerox1720     xnuppc+c        xnuppc-160x64    xterm+256setaf   xterm+pcf0      xterm-88color     xterm-r5       xterm1
xfce          xnuppc+f        xnuppc-160x64-m  xterm+alt+title  xterm+pcf2      xterm-256color    xterm-r6       xtermc
xiterm        xnuppc+f2       xnuppc-200x64    xterm+alt1049    xterm+pcfkeys   xterm-1002        xterm-sco      xtermm
xl83          xnuppc-80x25    xnuppc-200x64-m  xterm+app        xterm+r6f2      xterm-1003        xterm-sun      xterms
xnuppc        xnuppc-80x25-m  xnuppc-200x75    xterm+direct     xterm+sl        xterm-1005        xterm-utf8     xterms-sun
xnuppc+80x25  xnuppc-80x30    xnuppc-200x75-m  xterm+direct2    xterm+sl-twm    xterm-1006        xterm-vt52     xwsh


This defines the default editor which is used to edit text files on your system. Whichever text editor this variable points to shall be loaded when you use the edit command or use shortcuts like Ctrl+X+E

This same editor is used when invoking commands like sudoedit. It is generally preferred to set this variable to point at vim instead of nano [Read the difference between vim and nano]


PATH is probably the most interesting Environment Variables in Linux according to me. It basically consists of a list of directories were the system looks for a command’s executable/script. For example, when we type a command like ls, the system searches for an executable or a script with the same name in the directories listed in PATH from the start and executes the first instance of ls it finds.

Sometimes, you might want to have your own set of special binaries which you might want to run as commands. You can do this by adding the directory in which they are contained to the PATH.

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

However, you must be careful as if any of the binaries don’t have the same name as any other system binaries/scripts because the system executes the first instance of the binary/script it finds.


Apart from the Environment Variables in Linux listed here, there are several other which might be of interest to users depending on the context. You can also modify these Environment variables in Linux to alter the Environment the of programs. To know how we can alter the Environment Variables, check out this post.