yesterday's date

Shell Programming and Scripting
1

I was playing to find a simple way to get yesterday's date, and came up with this (on an AIX 5.2 box):

$ date
Thu Feb 19 11:21:26 EST 2009
$ echo $TZ
EST5EDT
$ yesterday=`TZ=$(date +%Z)+24 date`
$ echo $yesterday
Wed Feb 18 16:21:52 GMT 2009

Why it is converted to GMT instead of using straight EST5EDT? How can I force it to be EST5EDT?

Any thoughts? TIA

2

I needed to get yesterdays date just yesterday and came up with this:

/opt/freeware/bin/date -d "-1 day" +"%D"

this will work if your aix box has the gnu coreutils installed.

3

Yes but we can't rely on GNU date. Thanks.