From: "Berger, Daniel" <Daniel.Berger@...>
Date: 2006-08-26T05:14:08+09:00
Subject: Re: Can you temporarily turn off STDERR ??

> -----Original Message-----
> From: ara.t.howard@noaa.gov [mailto:ara.t.howard@noaa.gov] 
> Sent: Friday, August 25, 2006 1:46 PM
> To: ruby-talk ML
> Subject: Re: Can you temporarily turn off STDERR ??
> 
> 
> On Sat, 26 Aug 2006, bradjpeek wrote:
> 
> > Inside a ruby script I want to:
> >
> > 1)  redirect STDERR to /dev/null
> > 2)  Issue a system call (e.g. system(tar xf tarfile file) )
> > 3)  revert to normal STDERR output
> >
> > I have a script that issues 3-4 system calls that are returning the 
> > following message to STDERR:
> >
> > warning: Insecure world writable dir /opt, mode 040777
> >
> > I'd like to suppress these messages (Let's assume that I 
> can't change 
> > the permissions on /opt).
> >
> > An example of one of the lines that is throwing the error is:
> >
> > x = `tar tf mytar.tar`   #  envoke the unix tar command
> > print x
> 
> the warning is from ruby.
> 
>    $VERBOSE = nil
> 
> will shut it up
> 
> if you want it shut up only sometimes do
> 
>    def quiet
>      v = $VERBOSE
>      yield
>    ensure
>      $VERBOSE = v
>    end
> 
> then
> 
>    x = quietly{ `tar tf mytar.tar` }
>    print x
> 
> > Any suggestions?
> 
> if you really want fine control over stdin/stdout/stderr of 
> executed commands check out my session and open4 libs
> 
>    http://codeforpeople.com/lib/ruby/session/session-2.4.0/README
>    http://codeforpeople.com/lib/ruby/open4/open4-0.5.1/README
> 
> in particular the Open4::spawn command.  both are available as

This comes up often enough that I wonder if allowing IO#reopen to take a
block would be a good idea:

$stderr.reopen('/dev/null') do
   # Code here redirects to /dev/null
end

# Code outside the block behaves normally

I thought this idea had been brought up before, and that there was some
downside to this, but I can't find any references to it now.

Thoughts?

- Dan


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