subprocess - How to run external executable using Python?

22
votes

I have an external executable file which I am trying to run from a Python script. CMD executable runs but without generating output. Probably it exit before output can be generated. Any suggestion about how to delay exit until outputs are generated?

import subprocess, sys
from subprocess import Popen, PIPE
exe_str = r"C:/Windows/System32/cmd C:/temp/calc.exe"

parent = subprocess.Popen(exe_str, stderr=subprocess.PIPE)
4
pythonsubprocessexecutable
Maybe you are right. Input data is elevation and flow direction that is why i posted it here. - Ibe
DOS? Do you not mean a command line interface (CLI) appliction? MS-DOS was discontinued over 12 years ago. - blah238
yes I mean command prompt. thanks for clarifying it. - Ibe
It worked from SO example using os: import sys, string, os os.chdir( 'c:\\temp' ) os.system( '"C:\\temp\\calc.exe"' ) Not sure why subprocess isn't working. - Ibe

4 Answers

18
votes

use subprocess.call, more info here:

import subprocess
subprocess.call(["C:\\temp\\calc.exe"])

or 

import os
os.system('"C:/Windows/System32/notepad.exe"')

i hope it helps you...

12
votes

The os.system method is depreciated and should not be used in new applications. The subprocess module is the pythonic way to do what you require.

Here is an example of some code I wrote a few weeks ago using subprocess to load files, the command you need to use to delay exit until data has been received and the launched program completes is wait():

import subprocess

cmd = "c:\\file.exe"
process = subprocess.Popen(cmd, stdout=subprocess.PIPE, creationflags=0x08000000)
process.wait()

creationflags=0x08000000 is an optional parameter which suppresses the launch of a window, which can be useful if the program you are calling does not need to be directly seen.

5
votes

Option 1

import subprocess

subprocess.call('C:\Windows\System32\calc.exe')

Option 2

subprocess.Popen(['C:\Windows\System32\calc.exe'],stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True).communicate()

Option 3

import os
os.system('C:\Windows\System32\calc.exe')
0
votes

This worked for me after trying everything else: Change the location of your python program to be the same as where the .exe is located. And then the simple:

subprocess.call("calc.exe")

would work.