Python run commands in one instance of CMD

Question

I have this code:

import os

os.system('set x=5')
os.system('echo %x%')

When I do this, I expect to get 5 outputted to the screen, but instead I get %x%. I think this is because these two commands are being run on 2 different command prompt instances. If anyone can help, that would be greatly appreciated!

But assuming I want to do it from 2 separate commands, what would I do? — SomeMosa
– SomeMosa, Commented Sep 18, 2019 at 0:35

YONGSOO KIM · Accepted Answer · 2019-09-18 00:50:35Z

1

It seems "set" command should be replace with "os.environ" method in python. This way, you can set environment variable.

import os
os.environ['x'] = "5"
os.system('echo %x%')

#result is "5"

I think this is the easiest way to achieve your goal. Hope this can help you:)

edited Sep 18, 2019 at 0:50

answered Sep 18, 2019 at 0:42

YONGSOO KIM

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2 Comments

SomeMosa Over a year ago

Thank you for your reply, but as I said above, I would like to do it from 2 separate commands. The example I have given is a simplified version of what I hope to do.

YONGSOO KIM Over a year ago

@Pokechu48 thank you for your quick feedback. I changed my reply. I think you should use "os.environ" instead of using "set" command in "os.system" method.

Ryan Mcconnell · Accepted Answer · 2019-09-18 01:33:18Z

0

It's not exactly recommended to do this but if you really want to programmatically interface with a console emulating the way you would do it normally you can manipulate the stdin and stdout buffers. The subprocess module has some tools for that in python.

import subprocess

p = subprocess.Popen('cmd.exe', stdin=subprocess.PIPE, stdout=subprocess.PIPE, universal_newlines=True)
p.stdin.write('set x=5\n')
p.stdin.write('echo %x%\n')
print p.communicate()[0]
p.terminate()

answered Sep 18, 2019 at 1:33

Ryan Mcconnell

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