From: Stefano Crocco <stefano.crocco@...>
Date: 2007-12-27T23:53:45+09:00
Subject: Re: Capturing error msgs from output = `cmd`

Alle giovedì 27 dicembre 2007, Victor Reyes ha scritto:
> Team,
>
> First, thank you for all your suggestions. They are greatly appreciated.
>
> I tried the:
> *userCMD_output* *= `#{input} 2>&1`*
> But could not capture the error. Matter of facts the error to the *ls
> *command was displayed on the screen as:
> *ls: 0653-341 The file totot does not exist. *

Are you trying it in IRB? in this case, maybe what you see is the return 
value. Try puts userCMD_output and see whether it contains the error message 
or not. I tried this and it works:

irb(main):001:0> res = `ls abc 2>&1`
=> "ls: impossibile accedere a abc: No such file or directory\n"
irb(main):002:0> res
=> "ls: impossibile accedere a abc: No such file or directory\n"

> Second, I tried using the *Open3* method and when I tried to display the
> content of stdin, stdout and stderr just to inspect their contents, this is
> what's there:
>
> *stdin, stdout, stderr = Open3.popen3(input)*
>
> puts stdin
> puts stdout
> puts stderr
>
> *#<IO:0x20060638>
> #<IO:0x200605fc>
> #<IO:0x20060598> *

I don't understand how this works very well (I just started experimenting with 
Open3 yesterday), but I think you need to call their read methods, just as 
you'd do with a file:

puts stdout.read
=> ...

This won't work with stdin (if I remember correctly) because it's not open for 
writing.

I hope this helps

Stefano