caljd.sh

[Charles McCary]

Mr. Stephenson,

Just downloaded your script and it's great. One question for you though regarding this usage:

cal.sh -Y -s $(cal.sh -p 1)

This produces yesterday's date in the following format:

20020507

Does this work across years, so that when I run this script on 20030101, it will still output 20021231?

Does this have any problems with leap years?

Are there any downfalls with using this when I always want to produce only yesterday's date?

I'm sure I'm just being paranoid (what sysadmin isn't a little paranoid) but I'll sleep better hearing it from the Author's fingertips.

tx,
c

[A. Clay Stephenson · Accepted solution]

Hi Charles:

Does a hog like slop? Julian days count sequentially from 4713BCE to far into the future. They are used by astronomers to simplify orbital calculations. It knows all about leap years, about century years not being leap years (unless divisble by 400) and it knows all this without a single if statement. It also does "30 Days hath September ..." without an if statement. By the way, there is a newer Perl based version 'caljd.pl' with exactly the same arguments/options as caljd.sh.

I suggest that you download caljd.pl and try it as well; it executes quite a bit faster than the Shall/awk based 'caljd.sh'.

Version 2.05 is the latest version of both.




Regards, Clay

[Charles McCary]

Thanks - that's what I needed.