From: Reimer Behrends <behrends@...>
Date: 2003-12-07T22:52:03+09:00
Subject: Re: Trying to create a Ruby daemon

Samuel Kvarnbrink (samuel.kvarnbrink@humlab.umu.se) wrote:
>  Hi,
>  Does anyone here have an example on how to create a Ruby daemon that 
>  runs as a session leader (without a controlling terminal)? I've tried 
>  to accomplish that using fork and Process.setpgrp, but the only results 
>  so far have been zombie processes or processes that exit when I close 
>  the terminal. I'm quite new to Ruby so I guess that I've missed some 
>  little detail somewhere... :)

Daemonization in seven easy steps [1]:

  exit if fork                   # Parent exits, child continues.
  Process.setsid                 # Become session leader.
  exit if fork                   # Zap session leader. See [1].
  Dir.chdir "/"                  # Release old working directory.
  File.umask 0000                # Ensure sensible umask. Adjust as needed.
  STDIN.reopen "/dev/null"       # Free file descriptors and
  STDOUT.reopen "/dev/null", "a" # point them somewhere sensible.
  STDERR.reopen STDOUT           # STDOUT/ERR should better go to a logfile.

Refine as necessary.

			Reimer Behrends

[1] http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16