10 Jul
2014
10 Jul
'14
2:43 p.m.
On Thu, Jul 10, 2014 at 2:52 PM, Warren Toomey
<[1]wkt(a)tuhs.org> wrote:
    close fd 0 and fd 1
    dup() read end of pipe 1 to be stdin (fd 0)
    dup() write end of pipe 2 to be stdout (fd 1)
    exec("/bin/cat")
On Thu, Jul 10, 2014 at 03:06:11PM +1000, Christopher Vance wrote:
Hi, Warren.
That still leaves a process, even if it is a relatively lean one.
Hi Chris! Very true.
Besides your fd 0 is presumably already the read
end of the input pipe,
and fd 1 is already the write end of the output pipe. You could
probably reduce the whole thing to the last line.
Of course. If the shell set up the pipeline then we only have to exec("cat")
and leave /bin/cat shuffling the data from one pipe-end to the other.
As there are two distinct pipes, each with their own buffers, I can't see
a way of coalescing them into a single pipe without, as Chris suggests,
some kernelly goodness. Indeed, ugliness and complexity kernel-wise!
Cheers, Warren