From: Roger Pack <rogerpack2005@...>
Date: 2010-07-23T04:37:29+09:00
Subject: Re: How to avoid black-windows using system() ?


> RC> I thought that when you call system() with only one parameter, 
> cmd.exe
> RC> is used but when you call system() with more than one parameter, the
> RC> program is directly launched without cmd.exe
> 
> RC> Can you confirm that ?


I think I know where the confusion lies.
from [1] it reads

" If exec is given a single argument, that argument is taken as a line 
that is subject to shell expansion before being executed. If multiple 
arguments are given, the second and subsequent arguments are passed as 
parameters to command with no shell expansion"

The shell expansion it is referring to here is things like expanding 
paths, ex:
system("ls $HOME") gets expanded to system("ls /home/username")

however

system("ls", "$HOME")

does not get auto-expanded.

They both require "sub-shell" in windows because the process you are 
executing (montage.exe) requires somewhere to output its data to, so it 
pops up.  It is possible to make a program "not require an output shell" 
but most programs aren't setup that way (rubyw.exe is, ruby.exe isn't, 
for example).

Recommendation: use IO.popen("whatever").read to avoid popping it up.
GL.
-r



[1] http://ruby-doc.org/core/classes/Kernel.html#M005968

> 
> RC> thanks & regards.
> 
> I'm not sure I follow you ...
> 
> Have you tried the "back tick" processing to do what you want?
>   `d:/mes documents/___3D/imageMagick/montage.exe`

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