Catch stderr

ruby-talk
1

Thanks Paul,

The interesting thing is, I have tried this trick with Turbo C++ under
windows 2000. when I wrote a simple program calling int21/46, or the C dup2
function, and used “redir net use…”, it worked. But when I copied that
piece of asm or dup2 code into the C program that use system(“net use…”),
it does not work! So strange… It may not be a problem of ruby, so…

Shannon

···

From: “Paul Melis” paul@floorball.nl
Reply-To: ruby-talk@ruby-lang.org
To: ruby-talk@ruby-lang.org (ruby-talk ML)
Subject: Re: catch stderr
Date: Sun, 1 Dec 2002 00:58:55 +0900

“Shannon Fang” xrfang@hotmail.com wrote in message
news:20021129220610.990B.XRFANG@hotmail.com…

Hi,

I have some question about catching stderr output in ruby… Please read
the following simple code.

STDERR.reopen STDOUT
result=net use abc
print “res=”, result

while abc is not available on my LAN. I didn’t succeed in catch the
stderr output to my program.

Since you seem to be on windows, perhaps that is screwing up the redirect
stuff. Windows is not very good at the unix ways of I/O streams.

One way of capturing stderr (or actually redirecting) is using the “redir”
utility included in DJGPP (included in
ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2/djdev203.zip).
It allows you to redirect stderr to stdout (or a file), so you can do

irb(main):001:0> res = redir -eo net use abc
“System error 67 has occurred.\n\nThe network name cannot be found.\n\n”
irb(main):002:0> res
“System error 67 has occurred.\n\nThe network name cannot be found.\n\n”

Good luck,
Paul

The new MSN 8: smart spam protection and 2 months FREE*
http://join.msn.com/?page=features/junkmail