I want to use os.spawn* function to make a upstart service call. The reason to use os.spawn over subprocess is because os.spawn calls provides more control over the way the program is launched though with a little complex call signature.
My command is :
sudo start service/new_service db=tmp I am not sure how to run string command using os.spawn* function family.
The only 'more control' that os.spawn gives you over subprocess is the mode argument - but on Unix, this can only control whether the call blocks waiting for the subprocess to finish, which is also doable with subprocess.
In any case, the best way to turn your command into a list of arguments is to use the shlex.split function, as recommended by the subprocess docs:
command = 'sudo start service/new_sevice db=tmp' subprocess.call(shlex.split(command)) If you really want to use os.spawn* family (and you probably don't), you can also use shlex.split - it gives its result in the form subprocess expects which differs slightly from the form os.spawn* expect, but you can get around this easily enough using the spawnl* variants and Python's argument unpacking:
os.spawnlp(os.P_WAIT, *shlex.split(command)) 
subprocess.Popen('sudo start service/new_service db=tmp', shell=True, stderr=subprocess.STDOUT) Yes child process spawning should be nonblocking too.
os.spawn* either. The best way to achieve that (since you don't want to block waiting for the child to finish) is likely to check proc.poll() is not None occasionally (where proc is the return value of Popen) - once that condition is true, the child process has stopped. Alternatively, you might want to use the standard multiprocessing module to play double fork games - spawn a new Python process whose only job is to block waiting for the spawned sudo to finish, and then terminate itself and its parent.
subprocessfor this? Your statement of "More control" is based on what exactly? Thesubprocessmodule is developed specifically for the needs you require, and the command you detailed in your question is a perfectly normal command to run withsubprocess.subprocess.Popen('sudo start service/new_service db=tmp', shell=True, stderr=subprocess.STDOUT)However even after the child process gets terminated, the calling process dont get terminated.