Forking into the background (Linux)
hansmu at xs4all.nl
Mon Dec 24 02:56:35 CET 2012
On 24/12/12 01:50:24, Olive wrote:
> My goal is to write a script that 1) write something to stdout; then
> fork into the background, closing the stdout (and stderr, stdin) pipe.
> I have found this answer (forking -> setsid -> forking)
> However the standard output of the child is still connected to the
> terminal. I would like that if we execute a subprocess.checkprocess on
> this program, only "I would like to see this" is captured and that the
> program terminates when the parent exits.
> #! /usr/bin/python2
> import os,sys,time
> print "I would like to see this"
> pid = os.fork()
> if (pid == 0): # The first child.
> # os.chdir("/")
> # os.umask(0)
> pid2 = os.fork()
> if (pid2 == 0): # Second child
> print "I would like not see this"
> sys.exit() #First child exists
> else: # Parent Code
> sys.exit() # Parent exists
You could do this before forking:
sys.stdin = open('/dev/null', 'r')
sys.stdout = open('/dev/null', 'w')
sys.stderr = open('/dev/null', 'w')
You may want to look at the python-daemon module on Pypy, which appears
to do what you need, including some features you haven't asked for, yet.
Hope this helps,
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