[ale] Linux shell process

[Lightner, Jeff]

Unfortunately that works with the GNU date but not with proprietary implementations.





-----Original Message-----
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of Michael H. Warfield
Sent: Monday, March 19, 2012 3:10 PM
To: Atlanta Linux Enthusiasts
Cc: mhw at wittsend.com
Subject: Re: [ale] Linux shell process

On Mon, 2012-03-19 at 16:03 +0000, Lightner, Jeff wrote:
> I use cal to cheat at date math.  With grep and wc you can figure out many things more simply than with more esoteric methods.

For shell scripts, I use "date" for date math.

You gotta really get into the info stuff but the things you can do with
the date --date option are simply amazing...

[mhw at canyon ~]$ date --date=yesterday
Sun Mar 18 15:05:34 EDT 2012
[mhw at canyon ~]$ date --date="today - 1 month"
Sun Feb 19 14:05:41 EST 2012
[mhw at canyon ~]$ date --date="today - 3 weeks"
Mon Feb 27 14:05:51 EST 2012
[mhw at canyon ~]$ date --date="Mon Feb 27 14:05:51 EST 2012 - 3 weeks"
Mon Feb  6 14:05:51 EST 2012
[mhw at canyon ~]$ date --date="Mon Feb 27 14:05:51 EST 2012 - 3 weeks - 6 hours"
Mon Feb  6 08:05:51 EST 2012

It's documented in the info pages for date but not in the man pages (a
little too complex for man, I'm afraid).

Regards,
Mike
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