[TUHS] Command line options and complexity

Greg 'groggy' Lehey grog at lemis.com
Fri Mar 13 11:02:06 AEST 2020

On Wednesday, 11 March 2020 at 23:34:46 -0400, Steve Nickolas wrote:
> On Thu, 12 Mar 2020, Greg 'groggy' Lehey wrote:
>> -S isn't POSIX.  And to implement it without an option would mean
>> removing -h.
> -h is a gnuism, isn't it?

It might have originated there, but then I would expect it to be spelt
'--produce-human-readable-output'.  I haven't been able to establish
from the FreeBSD sources or commit logs when it was introduced.  It
would clearly have been a reimplementation.

> https://pubs.opengroup.org/onlinepubs/9699919799/utilities/ls.html does
> specify the -S switch.  That's POSIX, isn't it?

So it is!  This was the first option that I wanted to add, back when I
still had practice wheels.  I asked my mentor, and he said "not the
Unix way", so I let it be.  Then Wes Peters came up with the idea, and
I thought he committed it, but it seems that it ultimately came from
Kostas Blekos in 2005, based on the same feature on NetBSD and
OpenBSD.  I wonder when it made it to POSIX.

>> As I mentioned earlier, -t can't be done by a filter without
>> significantly modifying the timestamp output.  That was my rationale
>> for the -D option, which allows sorting by an external filter.
> Understandable.
> Honestly if the date format weren't standardized as it were, I would've
> standardized on "yyyy-mm-dd,mm:ss" - which wouldn't need special
> processing in order to pump into sort(1).

Yes, that was one of the possibilities I thought of.  Another obvious
one was time_t, which is even easier to process.  And then there's ISO
8601.  That's why it didn't take me long to decide "do it *your* way”
with the -D option.

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