Run Process and Don't Wait

Question

I'd like to run a process and not wait for it to return. I've tried spawn with P_NOWAIT and subprocess like this:

app = "C:\Windows\Notepad.exe" file = "C:\Path\To\File.txt"  pid = subprocess.Popen(     [app, file],      shell=True,      stdin=subprocess.PIPE,      stdout=subprocess.PIPE, ).pid 

However, the console window remains until I close Notepad. Is it possible to launch the process and not wait for it to complete?

Answer 1

This call doesn't wait for the child process to terminate (on Linux). Don't ask me what close_fds does; I wrote the code some years ago. (BTW: The documentation of subprocess.Popen is confusing, IMHO.)

proc = Popen([cmd_str], shell=True,              stdin=None, stdout=None, stderr=None, close_fds=True) 

Edit:

I looked at the the documentation of subprocess, and I believe the important aspect for you is stdin=None, stdout=None, stderr=None,. Otherwise Popen captures the program's output, and you are expected to look at it. close_fds makes the parent process' file handles inaccessible for the child.

Answer 2

I finally got this to work. I'm running "Python 2.6.6 (r266:84297, Aug 24 2010, 18:13:38) [MSC v.1500 64 bit (AMD64)] win32". Here's how I had to code it:

from subprocess import Popen DETACHED_PROCESS = 0x00000008 cmd = [     sys.executable,     'c:\somepath\someprogram.exe',     parm1,     parm2,     parm3, ] p = Popen(     cmd, shell=False, stdin=None, stdout=None, stderr=None,     close_fds=True, creationflags=DETACHED_PROCESS, ) 

This turns off all piping of standard input/output and does NOT execute the called program in the shell. Setting 'creationflags' to DETACHED_PROCESS seemed to do the trick for me. I forget where I found out about it, but an example is used here.