Re: [repost] Patch to make cpdup's stdout unbuffered

["Simon 'corecode' Schubert" <corecode@xxxxxxxxxxxx>]

On 09.06.2004, at 00:19, Chris Pressey wrote:

> > > The installer popen()'s "cpdup -vvv src dest" and it reads from this
> > > pipe to monitor cpdup's progress.  Unfortunately, since cpdup's
> > > output is fully buffered, cpdup's progress can't be usefully
> > > measured this way.
> > Now, we could add a flag for every single program to write unbuffered
> > (linebuffered) output. Or we could do some (non-POSIX?) magic in libc
> > to get most of this just fixed by doing a env
> > LIBC_STDOUT_BUFFERING=line $program or whatever...
> The man pages make it sound a bit like this is already possible, but I
> can't figure out how to do it.
> So by the sounds of it, the attached program should be able to run
> another program, forcing that other program's stdout to be unbufferred.
> But in (a small amount of) testing, I couldn't seem to get that
> behaviour.

The buffering is done in the FILE* functions in libc, not on 
STDOUT_FILENO in the kernel.

This is why we need to tell *libc* not to buffer; this has nothing to 
do with the fd as I understand it.

cheers
  simon

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