How to Execute a Command Prompt Command from Python

How to execute a command prompt command from python

You probably want to try something like this:

command = "cmd.exe /C dir C:\\"

I don't think you can pipe into cmd.exe... If you are coming from a unix background, well, cmd.exe has some ugly warts!

EDIT: According to Sven Marnach, you can pipe to cmd.exe. I tried following in a python shell:

>>> import subprocess
>>> proc = subprocess.Popen('cmd.exe', stdin = subprocess.PIPE, stdout = subprocess.PIPE)
>>> stdout, stderr = proc.communicate('dir c:\\')
>>> stdout
'Microsoft Windows [Version 6.1.7600]\r\nCopyright (c) 2009 Microsoft Corporatio
n.  All rights reserved.\r\n\r\nC:\\Python25>More? '

As you can see, you still have a bit of work to do (only the first line is returned), but you might be able to get this to work...

How do I execute a program or call a system command?

Use the subprocess module in the standard library:

import subprocess
subprocess.run(["ls", "-l"])

The advantage of subprocess.run over os.system is that it is more flexible (you can get the stdout, stderr, the "real" status code, better error handling, etc...).

Even the documentation for os.system recommends using subprocess instead:

The subprocess module provides more powerful facilities for spawning new processes and retrieving their results; using that module is preferable to using this function. See the Replacing Older Functions with the subprocess Module section in the subprocess documentation for some helpful recipes.

On Python 3.4 and earlier, use subprocess.call instead of .run:

subprocess.call(["ls", "-l"])

Execute CMD Command using python after opening CMD with specific directory

What you can do is that you have to change your working directory first before executing the code.

import os

os.chdir('C:\\Users\\Name\\Desktop\\testing')
os.system("start cmd /K py <filename> –V <variant string> -p <path to the flash files>")

Running windows shell commands with python

The newer subprocess.check_output and similar commands are supposed to replace os.system. See this page for details. While I can't test this on Windows (because I don't have access to any Windows machines), the following should work:

from subprocess import check_output
check_output("dir C:", shell=True)

check_output returns a string of the output from your command. Alternatively, subprocess.call just runs the command and returns the status of the command (usually 0 if everything is okay).

Also note that, in python 3, that string output is now bytes output. If you want to change this into a string, you need something like

from subprocess import check_output
check_output("dir C:", shell=True).decode()

If necessary, you can tell it the kind of encoding your program outputs. The default is utf-8, which typically works fine, but other standard options are here.

Also note that @bluescorpion says in the comments that Windows 10 needs a trailing backslash, as in check_output("dir C:\\", shell=True). The double backslash is needed because \ is a special character in python, so it has to be escaped. (Also note that even prefixing the string with r doesn't help if \ is the very last character of the string — r"dir C:\" is a syntax error, though r"dir C:\ " is not.)

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