shell> date --help
shell> date -d "1977-10-12"
Wed Oct 12 00:00:00 CST 1977
shell> date +"%c"
Sat 03 Jun 2017 12:23:57 PM CST
shell> date
Sat Jun 3 12:00:25 CST 2017
shell> TZ=GMT date
Sat Jun 3 04:00:25 GMT 2017
shell> date -d now
shell> date -d today
shell> date -d yesterday
shell> date -d tomorrow
shell> date -d sunday
shell> date -d last-sunday
shell> date -d "1977-10-12" +"%s"
245433600
shell> date -d @245433600
Wed Oct 12 00:00:00 CST 1977
shell> date -d "1977-10-12" +"%A"
Wednesday
shell> date +"%F"
2017-06-03
last
next
last-week
next-week
last-month
next-month
last-year
next-year
%a locale's abbreviated weekday name (e.g., Sun)
%A locale's full weekday name (e.g., Sunday)
%b locale's abbreviated month name (e.g., Jan)
%B locale's full month name (e.g., January)
%c locale's date and time (e.g., Thu Mar 3 23:05:25 2005)
%F full date; same as %Y-%m-%d
%s seconds since 1970-01-01 00:00:00 UTC
/etc/localtime
/usr/share/zoneinfo
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