Howdy all,
For making a Python program calve off an independent daemon process of
itself, I found Carl J. Schroeder's recipe in the ASPN Python Cookbook.
<URL:http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/278731>
This is a thorough approach, and I'm cribbing a simpler process from
this example. One thing that strikes me is that the algorithm seems to
depend on running the program as the root user.
import os
def become_daemon():
pid = os.fork()
if pid == 0:
# This is the child of the fork
# Become a process leader of a new process group
os.setsid()
# Fork again and exit this parent
pid = os.fork()
if pid == 0:
# This is the child of the second fork -- the running process.
pass
else:
# This is the parent of the second fork
# Exit to prevent zombie process
os._exit(0)
else:
# This is the parent of the fork
os._exit(0)
become_daemon()
# Continue with the program
The double-fork seems to be to:
- Allow the first forked child to start a new process group
- Allow the second forked child to be orphaned immediately
The problem I'm having is that 'os.setsid()' fails with 'OSError:
[Errno 1] Operation not permitted' unless I run the program as the
root user. This isn't a program that I want necessarily running as
root.
What does the 'os.setsid()' gain me? How can I get that without being
the root user?
--
\ "I went to a general store. They wouldn't let me buy anything |
`\ specifically." -- Steven Wright |
_o__) |
Ben Finney
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