On Tue, Aug 21, 2007 at 04:18:59PM +0200, Jan Danielsson wrote:
> Hello all,
> 
>    I'm trying to understand something about redirections.
> 
>    A long time ago, I learned that Unix applications use stdout and
> stderr for output. I also learned that > causes a redirection to a file.
> Pretty soon I found that some output wasn't redirected to the file, but
> that 2> or 2>&1 would solve that.

2> redirects stderr, 2>&1 redirects stderr into stdout, which is
probably what you want.

>    When I build packages, I use a script which rebuilds outdated
> packages in a chroot. Since these are batch jobs, I don't really see
> what packages have failed. I added support in my rebuild-script to make
> not of which packages failed. But that wasn't very helpful, since I need
> the error messages. So, I tried to redirect stderr to stdout (2>&1), and
> redirect stdout to a log-file when I call "make package".
> 
>    To my surprise, I still see a lot of output to the screen (though not
> even close to how much it's without the redirections). What's worse, the
> really relevant errors which cause packages to fail seem to be written
> to the terminal through other means that through the processes which
> have their terminal output redirected. For most packages, in my build
> log, I can see that it (make) has tried to execute a command, and that
> it failed. But but the actual error.
> 
>   For instance: emulators/qemu, games/scummvm
> 
>    chat/pidgin-silc also fails. Part of the error is only visible on
> screen, but it also writes some informational messages to my redirected
> file handles.
> 
>    Could someone explain why the shell redirections don't work? Also
> could someone explain how I can get all the build error messages to a
> log file?

It might help if you posted your script, or at least the sections of the
script that are handling the redirection and your invocation of said
script.

-- 
Michael Parson
mparson@bl.org