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

[Alejandro Colomar (man-pages)]

On 1/25/21 5:03 AM, Bernhard Voelker wrote:
> On 1/24/21 9:01 PM, Alex Henrie wrote:
>> I am definitely interested. Bernhard Voelker seemed to express
>> interest as well, conditional on -q being added to POSIX first.[1]
> 
> Just to clarify: I'm not as enthusiastic to add that option as it
> may have sounded.
> 
> Let me put it like this: if -q once gets standardized by POSIX,
> then we'd take it over in the GNU tee implementation.
> 
> Let me summarize so far:
> The suggestion is to solve the problem to save some data coming from
> a pipe as a different user.
> There are at least those known solutions:
>    - use > or >> redirection.
>    - use dd(1)
> 
> I have the impression that a home for this feature was searched
> in any tool, and as tee(1) already knew how to write to a file,
> had the "append" feature, and is often used in pipes, it was
> tempting to add it there.
> 
> But looking deeper, --quiet doesn't seem to fit well into 'tee'.
> It even contradicts to the title line in the man page:
>    "read from standard input and write to standard output and files"
> 
> 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.

I never knew what 'tee' meant.  That makes sense now.

> 
> 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.
> 
> Therefore, adding a feature which does not really fit is wrong, and
> contradicts the one-tool-for-one-purpose UNIX philosophy.
> 

Agreed.

> OTOH I understand that there's a little gap in the tool landscape.
> Astonishingly, there doesn't seem to exist a trivial tool to redirect
> from standard input (or any other input file descriptor) to a file.
> I wrote such a little tool in the attached:
> 
>    $ src/sink --help
>    Usage: src/sink [OPTION]... FILE
>    Copy input stream to FILE.
> 
>    Mandatory arguments to long options are mandatory for short options too.
> 
>      -a, --append              append to the given FILE, do not overwrite
>      -c, --create              ensure to create FILE, error if exists
>      -i, --input-stream=FD     read from stream FD instead of standard input
> 
>    The default input stream number FD is 0, representing the standard input.
> 
> This allows not only to copy data from standard input, but from any
> file descriptor open for reading.  It also allows control over
> how the output file will be opened (e.g. with O_CREAT|E_EXCL).
> 
> The OPs case would look like:
> 
>    echo 'foo' | sudo sink /etc/foo
> or
>    echo 'foo' | sudo sink -a /etc/foo  # append.
> or
>    echo 'foo' | sudo sink -c /etc/foo  # ensure creation of the file.
> 
> I'm not sure if this will ever be considered for inclusion -
> I just did it "for fun". ;-)

Tested-by: Alejandro Colomar <alx.manpages at gmail.com>
Reviewed-by: Alejandro Colomar <alx.manpages at gmail.com>

Much better than my patch.  :-)

> 
> Have a nice day,
> Berny
> 

Have a nice day!
Alex


--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/