Linux env Command

In Linux, we can use “env” command is used to either print environment variables.

In Linux, env command also used by shell scripts to launch the correct interpreter.

env Command Syntax

>>  env [OPTION]... [-][NAME=VALUE]... [COMMAND [ARG]...]

env command without any argument print out a list of all environment variables.

>>  env

Options	Description
-i --ignore-environment	Start with an empty environment.
-0 --null	End each output line with a 0 (null) byte rather than a newline.
-u --unset=NAME	Remove variable NAME from the environment.
--help	Display a help message and exit.
--version	Display version information and exit.
-	Same as -i.

-i or –ignore-environment or only – : runs a command with an empty environment

>>  env -i your_command

Note: This completely clear out the environment, but it does not prevent your_command setting new variables.

>>  env -i /bin/sh

To clear the environment (creating a new environment without any existing environment variables) for a new shell.

env -u or –unset remove variable from the environment.

>> env -u variable_name

>> env -u XDG_VTNR

Removing XDG_VTNR environment variable which you can see in the image above in the output of just env.

env -0 or –null command End each output line with NULL, not newline

>> env -0

env –version command Display version information and exit.

>> env --version

commonly-used environment variables	Description
EDITOR	The default file editor to be used.
HOME	The current user's home directory.
SHELL	The location of the current user's shell program.
TERM	The current terminal emulation.
PATH	Pathnames to be searched when executing commands.
MAIL	Location of where mail is to be stored.
MANPATH	Location of your manuals. See man command.
LOGNAME	The name of the current user.
TZ	The time zone used by the system clock.