* Dropping setuid and setgid privileges

* PID file handling: don’t start if the PID file already exists, otherwise write the PID line to the specified file, remove the PID file when program terminates

* Signal handling: make sure cleanup is done in response to appropriate signals

Optional extras usually present in well-behaved daemons:

* Redirect stdout and stderr to syslog

* Drop root privileges and switch to a specified user and group id

* Operate within a chroot jail

* Respawn on termination

* Cooperate with operation under initd or inetd

I’m rather disappointed that these widely-standardised daemon behaviours aren’t present in the Python standard library.

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1. Fork # Make new process 1
1.parent. Exit
1.child. Decouple from parent
os.chdir(”/”) # So we don’t tie up a file system
os.setsid() # Become a session/group leader
os.umask(0) # Could be other things here as well — allow core’s and what not.
1.child. Fork # Make new process 2
2.parent. Exit
2.child Close all open file descriptors in a pinch, these are 0-1023
2.child Open stdin, stdout and stderr to /dev/null use os.dup2() for this if you want.
2.child Congrats, you’re now a daemon.