Python 3 subprocess module throws error running “dir” on Windows

Question

This simple program in Python 3 throws errors. What could be the reason? This problem arose after I installed/reinstalled Python 3.5/3.6. Also

Answer 1

In addition to @grundic

It's not an executable, but built-in to the shell. [...]

If you really want to execute cmd built in commands, you have to execute cmd.exe /c COMMAND_HERE in your case:

import subprocess 
out = subprocess.check_output(['cmd.exe', '/c', 'dir'])

/c means that cmd.exe closes after execution

Answer 2

It seems that "dir" is not in your path. I do not know the full path of this executable on Windows but maybe you should replace dir by c:\windwos\system\dir

Or a best solution would be to use functions in the os modules to list directories:

os.listdir(path)

Answer 3

It's not an executable, but built-in to the shell. Python subprocess module can't find it, so you got an error.

If you would like to play with subprocess module, use some existing binary, e.g. python, notepad or ping. In case you need to list folder content, please use os.listdir or os.walk.