From: Alex Fenton <alex@...>
Date: 2005-09-08T23:51:30+09:00
Subject: Re: Problem with popen on windows

I too would dearly love to find a solution to this. I have seen this 
question
batted about several times over the years, but no solution.

I don't know cmd.exe is invoked, but presume it acts as the shell for 
system()
``() and popen(). The relevant lines in win32/win32.c in the Ruby source
seem to be in CreateChild (caution: IANA C-programmer)

	else if ((shell = getenv("COMSPEC")) &&
		 ((redir < 0 ? has_redirection(cmd) : redir) ||
		  isInternalCmd(cmd, shell))) {
	    char *tmp = ALLOCA_N(char, strlen(shell) + len + sizeof(" /c "));
	    sprintf(tmp, "%s /c %.*s", shell, len, cmd);
	    cmd = tmp;
	}

Looking at this code and the cmd.exe reference at
www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/cmd.mspx

it seemed worth trying
ENV['COMSPEC'] += ' /q'
in Ruby to see if switching cmd.exe's echo off would suppress the annoying
box pop-up. But having done this, any system, ``,  popen call then fails
with ENOENT - as if Windows can't then locate the shell executable.

Using command.com works for me, but still shows a pop-up box, and I
can't see any suitable options to suppress it.

I'm stumped from here, but perh someone with a better knowledge of
Windows process internals and/or Ruby internals can help.

alex

Kroeger Simon (ext) wrote:
> Hmm, this has no effect on the backqoutes thingie. It has an effect on
> popen but whatever I put in COMSPEC it just stops working. 
> 
> C:\WINNT\system32\cmd.exe is the standard, i tried:
> 
> C:\WINNT\system32\command.com
> C:\WINNT\system32\cmd.exe /MIN
> and empty
> 
> all have the same effect: no window poping up (fine) but no process is
> executed also (not so fine)
> 
> why is cmd.exe started anyway?
> 
> cheers
> 
> Simon
> 
> 
> 
>>From: Robert Klemme [mailto:bob.news@gmx.net] 
>>
>>Kroeger Simon (ext) wrote:
>>
>>>Hi all,
>>>
>>>i'm using ruby 1.8.2 (2004-12-25) [i386-mswin32] on win2000.
>>>
>>>When starting my GUI app with rubyw (because i don't like the empty
>>>window) there is another window poping up whenever i call popen. (or
>>>use backquotes to start another process)
>>>
>>>Using just ruby.exe all seems fine (except the initial nasty empty
>>>window)
>>>
>>>Someone knows a way around?
>>
>>Untested: maybe you can change COMSPEC env var in your ruby script to
>>point to another binary that won't open a window before 
>>executing the new
>>process.  Another option might be to add a command line param 
>>to COMSPEC -
>>although I don't know whether that would work.
>>
>>Kind regards
>>
>>    robert
>>
>>
>>
> 
> 
>