From: "Iñaki Baz Castillo" <ibc@...>
Date: 2009-12-13T21:55:43+09:00
Subject: Re: Is it possible to force a Ruby program to run as a proc name different than "ruby"?

El Domingo, 13 de Diciembre de 2009, Robert Klemme escribió:
> On 13.12.2009 00:51, Iñaki Baz Castillo wrote:
> > El Sábado, 12 de Diciembre de 2009, Robert Klemme escribió:
> >> This is what I would do:
> >>
> >> VAR='/var/run'
> >>
> >> pid_file = File.join(VAR, File.basename($0) + '.pid')
> >>
> >> begin
> >>     old_pid = File.read(pid_file).to_i
> >>     Process.kill 0, old_pid
> >>     $stderr.puts "ERROR: already running with PID #{old_pid}"
> >>     exit 1
> >> rescue Errno::ENOENT
> >>     # no pid file
> >> rescue Errno::ESRCH
> >>     # process not running
> >>     $stderr.puts 'WARNING: stale pid file'
> >> end
> >>
> >> # open file with EXCL in order to catch race conditions where two
> >> # processes were started almost at the same time and both thought
> >> # they would be a new instance.  Uncomment sleep to simulate:
> >> # sleep 2
> >> File.open(pid_file, File::EXCL | File::WRONLY | File::CREAT) {|io|
> >> io.write($$)}
> >> trap(0) {File.delete pid_file}
> >>
> >> puts "OK, here we go."
> >
> > Let me a question: is the above a fragment of a Linux init script written
> > in Ruby (rather than bash/sh as usual)?
> 
> That was hacked together for demonstration purposes.  It was not
> intended as an init script but rather as the demon itself - albeit
> without all the demonization stuff (detaching from terminal etc.)
> because I wanted to focus on the aspect of pid file handling and killing.

Ok ok, I just asked as curiosity because some time ago I tryed to do a init 
script in Ruby and couldn't do it properly... not remember the reason right 
now...


> > If so, according to LSB specifications it should return 0 (success) in
> > case of "start" action when the daemon is already running.
> 
> Well, if you write a start script for that "ruby demon" you would have
> to handle exit codes properly.

Ok, so later the init script could get "1" and return "0" as LSB states.

Thanks a lot again.

-- 
Iñaki Baz Castillo <ibc@aliax.net>