TL`DR: I wouldn't mind the SuMoTuWeThFrSa change in cal(1)
but I don't really give a damn either way.
MS> Well, how would you use date(1) to return the number of days in any
MS> given month, for example?
% xargs -I MON date -d '1-MON +1 month -1 day' +'%m %d'
july
07 31
june
06 30
jan
01 31
^D
I side with Martin Husemann: most of the calendar-oriented scripting
in my career is based on date(1) rather than cal(1), even though
the date(1) parsing syntax varies *wildly* between Unix/Linux versions.[*]
Note that OpenBSD has the English two-letter weekdays hard-wired
in /usr/src/usr.bin/cal/cal.c whereas the Linux and FreeBSD cal(1)
versions actually respect the LC_TIME locale setting. Your goal
of "aligning NetBSD with the rest" is a bit ephemeral because
the rest isn't really aligned, either.
Personally, I care very little about single vs double letter weekdays
in the cal(1) header. POSIX says I shouldn't (the heading is unspecified).
I'd consider a consistent 1- or 2-lettering aesthetically more
pleasing and an improvement wortwhile enough to break compatibility
with the past.
We all can even tell which "S" is supposed to be what day. Incidentally,
where I live (Northern Germany) these two days happen to be called
Sonnabend
Sonntag
I'd prefer compact columns instead of getting this oh-so-dreadful
ambiguity in the five initial letters resolved :-)
Martin Neitzel
PS: MUCH more useful to me is a cal(1) option to put Mondays first.
(I use cal(1) daily in the office.)
With the NetBSD cal(1) we can even pull any weekday in front. For
scripting on weekdays, I would go via this route instead of relying
on the weekday lettering. This month's Thursdays:
% cal -d 4 | sed -n 's/^\(.[0-9]\).*/\1/p'
2
9
16
23
30
[*] and PPS: I happen to be able to find "next month's first Thursday"
using FreeBSDs date(1) easily:
% date -v1d -v+1m -v+thu
Thu Aug 6 15:55:05 CEST 2020
I am not 100% sure how to do the job with NetBSD's date(1). I may
be just lucky with
% date -d '+1 month 1 thu'
Thu Aug 6 00:00:00 CEST 2020
because today is the 1st of July. I better recheck this in a fortnight.
