export

Set a variable with export, read it with $NAME, list them all with env — and why programs only see exported ones.

>_ Try it: a simulated Linux, right herenothing runs on your computer

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Examples

export APP_ENV=production set a variable for this session
echo $APP_ENV read it back
env | grep APP find it in the list
printenv PATH where the shell looks for programs
unset APP_ENV remove it again
export every exported variable

How it works

An environment variable is a name with a value that programs can read: HOME, PATH, USER. export NAME=value creates one (no spaces around =).

Without export, NAME=value is only seen by your shell. With it, every script and program you start from here sees it too. It lasts until you close the terminal.

Syntax

export NAME=value  |  echo $NAME  |  unset NAME

Options

Option	What it does
`NAME=value`	create or change a variable (no spaces around =)
`$NAME`	the value, wherever you write it
`env`	list every exported variable
`unset NAME`	remove it

Good to know

export NAME = value (with spaces) fails: the shell reads it as three separate words.
To keep a variable for every new terminal, put the export line in ~/.bashrc. Containers get theirs with docker run -e NAME=value.