Yesterday's date on Linux

[sape007]

Hi,

OS: RedHad 4

I use below in my .sh script

DAY=`(date '+%a')`

how can I get DAY_1 to have yesterday's day and DAY_2 to have day for two days ago. No luck with the man pages

Thanks in advance for any help.

[devils casper]

Hi and Welcome !

DAY_1=`(date --date='1 days ago' '+%a')`
DAY_2=`(date --date='2 days ago' '+%a')`
echo $DAY_1 $DAY_2

[sape007]

Thank you very much.

[wje_lf]

Since my man page doesn't cover that little trick, I went a'googling. I found enough info to help me write this demonstration script:

#!/bin/bash

set -o verbose on
date
date --date=now
date --date=today # same thing
date --date='3 seconds'
date --date='3 seconds ago'
date --date='4 hours'
date --date='tomorrow'
date --date='1 day'
date --date='1 days'
date --date='yesterday'
date --date='1 day ago'
date --date='1 days ago'
date --date='1 week'
date --date='1 fortnight'
date --date='1 month'
date --date='1 year'

Running it gave this output:

date
Thu Jan  3 07:42:47 PST 2008
date --date=now
Thu Jan  3 07:42:47 PST 2008
date --date=today # same thing
Thu Jan  3 07:42:47 PST 2008
date --date='3 seconds'
Thu Jan  3 07:42:50 PST 2008
date --date='3 seconds ago'
Thu Jan  3 07:42:44 PST 2008
date --date='4 hours'
Thu Jan  3 11:42:47 PST 2008
date --date='tomorrow'
Fri Jan  4 07:42:47 PST 2008
date --date='1 day'
Fri Jan  4 07:42:47 PST 2008
date --date='1 days'
Fri Jan  4 07:42:47 PST 2008
date --date='yesterday'
Wed Jan  2 07:42:47 PST 2008
date --date='1 day ago'
Wed Jan  2 07:42:47 PST 2008
date --date='1 days ago'
Wed Jan  2 07:42:47 PST 2008
date --date='1 week'
Thu Jan 10 07:42:47 PST 2008
date --date='1 fortnight'
Thu Jan 17 07:42:47 PST 2008
date --date='1 month'
Sun Feb  3 07:42:47 PST 2008
date --date='1 year'
Sat Jan  3 07:42:47 PST 2009