CODEWITHSUNDEEP
pythonwindowsconsolesubprocesspopen
Dan H
Dan H

Reputation: 14580

how to launch a command window from Python

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:

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!

Upvotes: 7

Views: 29196

Answers (5)

KaiLando
KaiLando

Reputation: 109

The code you might want would be

import os
os.system('cmd /k "[your command here]"')

I'm not sure if you would like it that way, but I just want to help.

Upvotes: 0

Garvit Joshi
Garvit Joshi

Reputation: 133

import os
os.system("start cmd")

Upvotes: 0

PGC channel
PGC channel

Reputation: 11

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)

Upvotes: 1

assassin44037
assassin44037

Reputation: 1

Code : 

user = raw_input("welcome to cmd: ")
def print_perms(chars, minlen, maxlen): 
    for n in range(minlen, maxlen+1): 
        for perm in itertools.product(chars, repeat=n): 
            print(''.join(perm))

Upvotes: 0

Rod
Rod

Reputation: 55882

You can use:

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

Upvotes: 11

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