how to set temporary environment variable windows command prompt like bash?

Question

In Bash I can create TEMPORARY environment variables on a command line. For eample

DEBUG=foo somecommand

This sets the environmnet variable DEBUG but only for somecommand. When the line is finished DEBUG is no longer set.

Can I do something similar in the Windows Command Processor?

Note: Using SET does not work. That sets the current command processors environment, not the just for the command about to be executed.

To give another example here's a small node.js program that prints the value of a single environment variable

// test.js console.log(`${process.argv[2]}='${process.env[process.argv[2]]}'`);

Let's run it in bash

$ export FOO=abc $ node test.js FOO FOO='abc'

Then let's run it with a temporary setting

$ FOO=def node test.js FOO FOO='def'

Check that FOO is still abc

$ echo $FOO abc

How I can accomplish the same thing in the Windows command prompt?

One way seems to be to relaunch the command processor as in

cmd /S /C "set "FOO=def" & node test.js FOO"

Is there another way or is that it?

"Is there another way or is that it?" I think that is the only way. set foo=bar && echo %foo% && set foo= && echo %foo% does not work :( — DavidPostill
– DavidPostill ♦, Commented Jan 28, 2018 at 7:32

mekb · Accepted Answer · 2019-06-08 01:22:21Z

5

Simply use the set command:

C:\>set foo=bar C:\>echo %foo% bar C:\>exit

Open cmd again

C:\>echo %foo% %foo% C:\>

answered Jun 7, 2019 at 22:51

3553 silver badges17 bronze badges

HackSlash · Accepted Answer · 2024-04-26 15:16:53Z

0

This can be done in a script with SETLOCAL and ENDLOCAL

EXAMPLE:

SETLOCAL set FOO=abc node test.js FOO ENDLOCAL

If you weren't running a script, you wouldn't need the variable you would simply:

node test.js abc

If you are generating commands programmatically, generate the script and run that, deleting it afterwards. I know, not ideal.

answered Apr 26, 2024 at 15:16

5,1053 gold badges23 silver badges42 bronze badges

2 Answers 2