From: Robert Klemme <shortcutter@...>
Date: 2010-01-17T01:50:09+09:00
Subject: Re: How to know if $stderr is reopened to /dev/null

On 01/16/2010 01:01 AM, Iñaki Baz Castillo wrote:
> El Sábado, 16 de Enero de 2010, Seebs escribió:
>> On 2010-01-15, Iñaki Baz Castillo <ibc@aliax.net> wrote:
>>> Hi, how could I know if $stderr has been redirected to /dev/null?
>> You couldn't.
>>
>> Consider a wrapper:
>>
>> 	exec 5>/dev/null
>> 	ruby foo.rb 2>&5
>>
>> Or for that matter, a file "/home/ibc/nulldev" which happens to be
>> a character special device using the same driver as /dev/null.
>>
>> ... Note that this assumes that what you care about is "$stderr is
>> being thrown away", not the exact path by which it's being done.
> 
> Thanks for the clarification. However it's enough for me using $stderr.tty?. 
> This is, I just care when $stederr is not pointing to a terminal.

Note though, that this also includes cases where stderr is redirected to 
a pipe.

robert@fussel:~$ ruby19 -e 'p $stderr.tty?'
true
robert@fussel:~$ ruby19 -e 'p $stderr.tty?' 2>&1 | cat
false
robert@fussel:~$

Kind regards

	robert

-- 
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