Calculate the date from 1125 days ago on non-GNU systems?

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                          On the Unix Bash commandline, I want to calculate the date from 1125 days ago using the base operating system (e.g. No Perl or Python).

On systems running GNU Date , I can do something like this:

    ubuntu $ date --date="1125 days ago"
    Wed Nov  7 15:12:33 PST 2007

FreeBSD or MacOSX systems don't ship with GNU Date, and don't support values like "X days ago".

    freebsd81 $ date --date="+1125 days ago"
    date: illegal option -- -

I *can* calculate a date from a few days ago on a Mac or FreeBSD system, but this is limited to a few days:

	# Today is really Dec 6, 2010. 4 days ago it was:
	macosx $ TZ=GMT+96 date +%Y%m%d
	20101202

	# But that doesn't work if I want to see the date 8 days ago:
	macosx $ TZ=GMT+192 date +%Y%m%d
	20101206

Can I calculate old dates on non-GNU systems without delving into tools like Perl or Python? Or must I use a more powerful scripting language?

Asked by Stefan Lasiewski (20733 rep)

Dec 6, 2010, 11:24 PM
Last activity: Jan 23, 2019, 09:22 PM

Calculate the date from 1125 days ago on non-GNU systems?

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