From: Christopher Rasch <crasch@...>
Date: 2008-02-26T09:49:34+09:00
Subject: Having trouble reading from stderr

Hi,

I'm trying to write a script that will establish an ssh tunnel through 
"gatewaymachine.com" to a "targetmachine" on the other side.  Sometimes 
there's already a tunnel established on the same port, in which case, 
the command fails with an error message.

I'd like to be able to read the error message from the script.  If the 
script failed due to an incorrect port number, I'd like increment the 
port number and try again.

Based on my google search, the popen3 command from the open3 library is 
what I want to use. 

But when I try to read from stderr, the read command never returns.  
Here's the code:



require 'open3'

stdin, stdout, stderr = Open3.popen3("ssh crasch@gatewaymachine.com -i 
/Users/crasch/.ssh/id_rsa.pub -L 2222:targetmachine:22 -N")

puts stderr.read <---hangs indefinitely here


Any suggestions for what might be happening?  Thanks for any suggestions 
you may wish to provide.

Chris