From: Nobuyoshi Nakada <nobu@...>
Date: 2009-04-25T10:10:51+09:00
Subject: [ruby-core:23308] Re: [Bug #1403] Process.daemon should do a double fork to avoid problems with controlling terminals

Hi,

At Sat, 25 Apr 2009 09:52:46 +0900,
Gary Wright wrote in [ruby-core:23307]:
> >> Author: Gary Wright
> >> Status: Open, Priority: Normal
> >> ruby -v: ruby 1.9.0 (2008-07-25 revision 18217) [i686-darwin9]
> >>
> >> Standard practice when 'daemonizing' is to do a second fork
> >> so that the final process is no longer a session leader and
> >> therefore can't acquire a new controlling terminal.
> >
> > See Process.setsid.  Process.daemon implies it.
> 
> setsid is not sufficient.  That makes the child process a session  
> leader, establishes a new process group, and breaks the association  
> with the controlling terminal, but it doesn't prevent the process from  
> acquiring a controlling terminal if it should happen to open a tty  
> device (generally on system V based systems, BSD systems are different).

Then `i686-darwin9' is irrelevant at all?

> The second fork ensures that the process (the grandchild of the  
> original process) is no longer a session leader and therefore can't  
> acquire a controlling terminal by opening a tty device.

Could you show concrete example?

-- 
Nobu Nakada