Using 'date' command smartly

Here I have shown some examples for using 'date' command in various forms. This will be helpful for deriving some logic in scripting.

Current time:
[root@hostxyz ~]# date
Fri Mar  4 12:37:29 CST 2011


Output only the day of week:
[root@hostxyz ~]# date +%a
Fri


Output the Time 1 hour before:
[root@hostxyz ~]# date +%Y%m%d%H%M%S -d  "1 hour ago"
20110304113732
[root@hostxyz ~]#


Output the Time 2 hours before:
[root@hostxyz ~]# date   --date='2 hour ago' +'%b %e %H:'
Mar  4 10:
[root@hostxyz ~]#

Finding Yesterday's day and assigning to a variable DAY_1:  
DAY_1=`(date --date='1 days ago' '+%a')`
echo $DAY_1

Finding day for two days ago and assigning to a variable DAY_2:

DAY_2=`(date --date='2 days ago' '+%a')`

echo $DAY_2