Run a .bat program in the background on Windows

Question

I am trying to run a .bat file (which acts as a simulator) in a new window, so it must always be running in the background. I think that creating a new process is the only option that I have. Basically, I want my code to do something like this:

    def startSim:
        # open .bat file in a new window
        os.system("startsim.bat")
        # continue doing other stuff here
        print("Simulator started")

I'm on Windows so I can't do os.fork.

see http://stackoverflow.com/questions/23397/whats-the-best-way-to-duplicate-fork-in-windows — jcomeau_ictx, Jun 23 '11 at 00:55
possible duplicate of [Python subprocess](http://stackoverflow.com/questions/1818774/python-subprocess) — Merlyn Morgan-Graham, Jun 23 '11 at 00:56
already read the one on making an os.fork on windows, I need something that I won't have to install a module or program(cygwin) to do it. — Vikram, Jun 23 '11 at 00:59

Artur Gaspar · Answer 1 · 2015-07-04T10:49:18.663

Use subprocess.Popen (not tested on Windows, but should work).

import subprocess

def startSim():
    child_process = subprocess.Popen("startsim.bat")

    # Do your stuff here.

    # You can terminate the child process after done.
    child_process.terminate()
    # You may want to give it some time to terminate before killing it.
    time.sleep(1)
    if child_process.returncode is None:
        # It has not terminated. Kill it. 
        child_process.kill()

Edit: you could also use os.startfile (Windows only, not tested too).

import os

def startSim():
    os.startfile("startsim.bat")
    # Do your stuff here.

score 2 · Answer 2 · answered Jun 23 '11 at 00:59

Looks like you want "os.spawn*", which seems to equate to os.fork, but for Windows. Some searching turned up this example:

# File: os-spawn-example-3.py

import os
import string

if os.name in ("nt", "dos"):
    exefile = ".exe"
else:
    exefile = ""

def spawn(program, *args):
    try:
        # check if the os module provides a shortcut
        return os.spawnvp(program, (program,) + args)
    except AttributeError:
        pass
    try:
        spawnv = os.spawnv
    except AttributeError:
        # assume it's unix
        pid = os.fork()
        if not pid:
            os.execvp(program, (program,) + args)
        return os.wait()[0]
    else:
        # got spawnv but no spawnp: go look for an executable
        for path in string.split(os.environ["PATH"], os.pathsep):
            file = os.path.join(path, program) + exefile
            try:
                return spawnv(os.P_WAIT, file, (file,) + args)
            except os.error:
                pass
        raise IOError, "cannot find executable"

#
# try it out!

spawn("python", "hello.py")

print "goodbye"

score 1 · Answer 3 · answered Jul 08 '13 at 17:46

import subprocess
proc = subprocess.Popen(['/path/script.bat'], 
                        stdout=subprocess.PIPE, 
                        stderr=subprocess.STDOUT)

Using subprocess.Popen() will run the given .bat path ( or any other executable).

If you do wish to wait for the process to finish just add proc.wait():

proc.wait()

score 1 · Answer 4 · edited May 23 '17 at 12:01

1

On Windows, a background process is called a "service". Check this other question about how to create a Windows service with Python: Creating a python win32 service

edited May 23 '17 at 12:01

Community

1
1

answered Jun 23 '11 at 01:27

Michael Dillon

31,973
6
70
106

Run a .bat program in the background on Windows

4 Answers4