how to launch a command window from Python

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Solution 1

You can use:

import os
os.system("start python perf_test.py 5")

Solution 2

Well I had the same problem. It was solved with this method. You should Try:

import os
os.system('chrome.exe') # open Chrome (.exe  file)
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Dan H
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Dan H

Updated on July 05, 2022

Comments

  • Dan H
    Dan H almost 2 years

    I'd like to use Python 2.6 on Windows to launch several separate command windows, each running their own Python script. The purpose is: these are clients, and I'm trying to load up the server with requests from multiple quasi-independent clients.

    I don't need to communicate with the client during or after the run, but I do need to send each a different commmandline arg, and I'd like each client's output to scroll in its own "console".

    From the DOS command line, the "start" command does what I'd like. I can either:

    start perf_test.py 2
    

    or

    start cmd /c perf_test.py 3
    

    or

    start cmd /c python perf_test.py 4
    

    (These will work for you if you have your "file associations" setup correctly for *.py files. There are other threads on that, if you need help. Or, use full paths to the python exe and/or your script.)

    My challenge is: How do I get the same effect from Python?

    Using subprocess library, I've tried variations like this:

    from subprocess import *
    p = Popen(["perf_test.py", "4"], shell=True, stdin=PIPE)
    

    But even with shell=True, the output is commingled in the window I'm already running in. Adding stdout=PIPE stops that, but then I have to read p.stdout or use p.communicate(). Adding "cmd" to the Popen gets approximately the same:

    p = Popen(["cmd", "/c", "perf_test.py", "4"], shell=True, stdin=PIPE)
    

    None of the above achieve the effect I'm looking for, which is: "pop open a new, distinct window for this script, and watch its output scroll by in its own console" (because I really want to run N of these clients in parallel).

    One other thing I turned to almost works, too.

    import os
    os.startfile("perf_test.py")
    

    This returns immediately, and an actual dosbox pops up. Yay! Success! That is, until I try to add an argument. This fails:

    os.startfile("perf_test.py 5")
    

    with error "The system cannot find the file specified"... because it is adding "[SPACE]5" to the filename. (The purpose of the argument is that each "perf_test" needs to have an assigned ID, so that they hit the server as different instances.)

    Other approaches I've considered, and really don't like for various reasons:

    • Run each "perf_test" in its own thread. (But I really want to see the output each in its own console.)
    • Make my own pseudo-consoles with Tk. (Figure I'll just hit different threading problems there.)
    • Dynamically write a .BAT file on the fly with the lines "start perf_test.py 1", "start perf_test.py 2", etc., then launch that .BAT file with Popen or startfile.

    I expect the last will work... and I guess is my last resort, if I can't get a Python script to do it directly.

    Thanks for any input / insights!

  • Zippy
    Zippy almost 8 years
    Why should OP use your code? Please give a more detailed answer