Quick startenv
Commands, used to run commands and interact with environment variables
Thisenv
Commands can be used to pass environment variables without setting them on the external environment (current shell).
Suppose you want to run a Node.js application and setUSER
Variable.
You can run
env USER=flavio node app.js
withUSER
Environment variables can be accessed from Node.js applications through Nodeprocess.env
interface.
You can also use the following command to run the command to clear all the environment variables that have been set:-i
Options:
env -i node app.js
In this case, you will receive an error message:env: node: No such file or directory
becausenode
The command cannot be accessed becausePATH
The variable used by the shell to find commands in the public path is not set.
Therefore, you need to pass the full path tonode
program:
env -i /usr/local/bin/node app.js
Try simpleapp.js
Files containing the following content:
console.log(process.env.NAME)
console.log(process.env.PATH)
You will see the output
undefined
undefinedYou can pass an env variable:
env -i NAME=flavio node app.js
and the output will be
flavio
undefinedRemoving the -i
option will make PATH
available again inside the program:

The env
command can also be used to print out all the environment variables, if ran with no options:
env
it will return a list of the environment variables set, for example:
HOME=/Users/flavio
LOGNAME=flavio
PATH=/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Library/Apple/usr/bin
PWD=/Users/flavio
SHELL=/usr/local/bin/fish
You can also make a variable inaccessible inside the program you run, using the -u
option, for example this code removes the HOME
variable from the command environment:
env -u HOME node app.js
The env
command works on Linux, macOS, WSL, and anywhere you have a UNIX environment
Download my free Linux Commands Handbook
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