Hi Pádraig,
> > $ (echo Hello; sleep 3; echo World) | stdbuf iconv -f ASCII
> > Hello
> > World
>
> From stdbuf.c /* FIXME: Should we mandate at least one option? */
Oops, I meant this:
$ (echo Hello; sleep 3; echo World) | stdbuf -i 0 iconv -f ASCII
Hello
World
Here too, the output comes only at the end, all at once.
> Anway I don't think that this works even if you specify -i0
> because fread() only seems to return after feof() or ferror()
Exactly. So, on which kinds of programs can -i0 work?
- Not in programs that use read(0,...) because they are not affected
by LD_PRELOADs.
- Not in programs that use fread().
- Not in programs that use getc() repeatedly - because the buffering
behaviour of stdio is independent of whether you use fread() or [f]getc().
Can you name a single program on which -i0 works?
> int main(void)
> {
> setvbuf (stdin, NULL, _IONBF, 0);
> setvbuf (stdout, NULL, _IONBF, 0);
But most program's _don't_ call setvbuf. If a program, like 'grep', has
an option like --line-buffered, then I don't need setvbuf.
> I'll might also add a note about fread() blocking (which POSIX requires)
> and that setting no _buffering_ doesn't impact that.
Yes, that seems to be the point. "no buffering" != "non-blocking".
Could 'stdbuf -i0' be changed to put file descriptor 0 into non-blocking state
before invoking the child process? Is that the solution?
Bruno
--
In memoriam Jürgen Ponto <http://en.wikipedia.org/wiki/Jürgen_Ponto>
