17 Sep
2024
17 Sep
'24
2:55 a.m.
On Mon, Sep 16, 2024 at 7:31 AM Edouard Klein <edouardklein(a)gmail.com> wrote:
George Michaelson <ggm(a)algebras.org> writes:
I suppose this depends entirely on the shell; perhaps that is the
point. Arguably, being the target of a pipe _and_ having a redirect on
stdin should be some kind of an error, but regardless, something that
is true is that is that the second `cat` command will only see
whatever is on `stdin` as it reads from `/dev/stdin`, but what is _on_
stdin can be confusing.
- Dan C.
cat is capable of endless discussion.
cat thing | cat otherthing doesn't do what (some) people think.
cat thing | cat otherthing /dev/stdin does, but there's an ordering
point to be made.
cat thing | cat < otherthing /dev/stdin makes the ordering point. and
the number of lines seen.
I'm not sure of the point you are making with your last example, which
gave me pause. I had to run it to see what it does.
I correctly guessed that only one of thing or otherthing would be printed,
but I was not able to guess if the | or the < would take precedence.
Is there a simple reason why the < has priority over | for the stdin ? If the < precedence was your point, why did you
specify /dev/stdin ?
cat thing | cat < otherthing
makes the point.
Is there a finer point I am missing ?
Sorry for being dense. I'm happy, after more that 20 years of Unixing,
to see something new even with such supposedly basic commands. Thank you
for your brain twister.