[PATCH v3 (resend)] tee: Add -q, --quiet, --silent option to not write to stdout

[Alex Henrie]

On Sun, Jan 24, 2021 at 9:04 PM Bernhard Voelker
<mail at bernhard-voelker.de> wrote:
>
> An off-tech argument: ask a local plumber if he'd would ever use
> a tee piece instead of a pipe end piece.  I guess he would only
> if he wouldn't have anything else at hand.

According to POSIX, tee writes to "zero or more files."[1] So the
"local plumber" analogy already doesn't hold, because a plumber would
never put in a tee and then immediately cap it off so that the flow
can only go to one place, but commands like `echo foo | tee | tee |
tee` are already explicitly allowed.

> A word to the proposed patch: what should happen, if the user does
> not give a file?
>   A | B | tee -q
> The patch just silently ignored that situation which feels wrong.

Personally, I like the idea of only having to type `echo foo | tee -q`
instead of `echo foo > /dev/null`, so I think the patch indeed does
the right thing in that case.

-Alex

[1] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/tee.html