sys64738

echo $(date +%s)/86400 | bc
echo $(($(date +%s)/86400))
let days=$(date +%s)/86400 ; echo $days

If perl is installed:

perl -e ' $days=int(time()/86400);print "$days\n"; '

perl -e 'print time(), "\n" '

date -d @<EPOCH time>
Example:
date -d @1368023418
Wed May  8 16:30:18 CEST 2013

perl -e "print scalar(localtime(1268727836))"

date -d 'Apr 30 14:40:09 2012' +%s

 date -d '14 days ago' +%s

Replace <username> with account in question

passwd -S <username>
<username> PS 2013-02-27 7 90 7 14 (Password set, SHA512 crypt.)

date -d "1 January 1970 + $(grep <username> /etc/shadow | awk -F: '{print $3}') days"

date -d '2012-08-08 16:00 UTC'
Wed Aug  8 18:00:00 CEST 2012

date -d '2012-12-08 16:00 UTC'
Sat Dec  8 17:00:00 CET 2012

date --utc
Wed Aug  8 12:35:15 UTC 2012