From: Sy <sy1235@...>
Date: 2005-04-16T09:08:22+09:00
Subject: "ruby script.rb" versus "xterm -e ruby script.rb"

Ok, so I decided to hack around with a project I might feasably get to
work.  Strangely enough, it actually works.  Except for reasons
unknown, I'm forced to include a kludge so that it works
_consistantly_.  I'm curious to learn about this inconsistancy, and
because I simply have no clue, I'd like to ask for some opinions.

Overview: Accept input and then launch that process.

# ------ begin script
command_line = gets.chomp
command_line = "nohup " + command_line.to_s + "&exit"
system(command_line)

# we can still continue to do other stuff.
# ------ end script
script home: http://sysy.homeip.net/mw/index.php/TRN_-_Launcher

Except that thanks to my preferred method of calling it, it only
inconsistantly works.

* Method 1 (always works):

ruby script.rb
xterm

This launches the script, and when I type in "xterm", xterm gets
launched and then script.rb exits.

* Method 2 (rarely works)

xterm -e ruby script.rb
xterm

This launches an xterm window which launches the script, and when I
type in "xterm", xterm only *sometimes* launches.


* Note: freely replace "xterm" with "rxvt".. both seem to act the same


* The Kludge

Append this:

pause = gets

and the launcher always works as expected, with both methods of
running the script.


Or append this:

10000.times do
   puts "do something stupid to delay exiting"
end

and (for me), the launcher always works as expected.  However, when I
lowered this to 1,000 it was still inconsistant.

Yes, I didn't know how to make ruby pause / think in a more
"efficiant" non-horribly-kludged way.  But my intutition told me that
xterm -e had xterm exit so fast that the script it was supposed to
execute.. wasn't.

--

So.. I am guessing that during a failure in "xterm -e ruby script.rb"
one of these must be true:

* xterm is not launching ruby script.rb
* ruby is not running script.rb
* script.rb is not launching my command (via "system")
* "nohup" within script.rb is not launching my command
* my command is having problems with being executed in this manner.

--

Ideas?
What have I missed?