date
The date shell command
date behaves differently between gnu and bsd. In OS X you can install gnu date by doing brew install coreutils
GNU date
Show adjusted date/time
date -d -2month # two months ago
date -d +1hour # one hour in the future
date -d +15minute
date -d "last week + 1 hour"
date -d "january 10 1978 + 5 years" +%a
Convert a string date to epoch seconds
date -d "Fri Sep 7 2:00 2012" +%s
Convert epoch seconds to string date
date -d @1375899534
Output various RFC 3339 time formats
date --rfc-3339=date
date --rfc-3339=seconds
date --rfc-3339=ns
Show and number all previous weeks from one year ago
for X in {1..53} ; do printf "%02s " ${X} ; date -d -49weeks-2days+${X}week "+%b %d %Y" ; done ;
Show and number all weeks from the point I started working at Zoosk
for X in {1..90} ; do printf "%02s " ${X} ; date -d "June 10 2013 - 1 week + ${X} week" "+%a %b %d %Y" ; done ;
Show how many seconds old I am
echo "$(date +%s) - $(date -d "January 10 1978 7:46pm" +%s)" | bc
Show subsecond date, without going full nano
for X in {1..100} ; do date +%s.%N | cut -c1-15 ; done ;
Sleep until the next 5 minute 0 seconds mark
while sleep $(date "+60 - %S.%N" | bc) 240 ; do date "+%F %T.%N" ; done ;
Show all format strings and their values
$ man date | awk '/[[:space:]]%/ {X = $1 ; $1 = "" ; print X,$0}' | while read -r Y Z ; do date "+%$Y^$Y^${Z//%/%%}" ; done | column -t -s^
% % MON literal %
%a Mon locale's abbreviated weekday name (e.g., Sun)
%A Monday locale's full weekday name (e.g., Sunday)
%b Nov locale's abbreviated month name (e.g., Jan)
%B November locale's full month name (e.g., January)
%c Mon 22 Nov 2021 10:33:55 AM PST locale's date and time (e.g., Thu Mar 3 23:05:25 2005)
%C 20 century; like %Y, except omit last two digits (e.g., 20)
%d 22 day of month (e.g., 01)
%D 11/22/21 date; same as %m/%d/%y
%e 22 day of month, space padded; same as %_d
%F 2021-11-22 full date; like %+4Y-%m-%d
%g 21 last two digits of year of ISO week number (see %G)
%G 2021 year of ISO week number (see %V); normally useful only with %V
%h Nov same as %b
%H 10 hour (00..23)
%I 10 hour (01..12)
%j 326 day of year (001..366)
%k 10 hour, space padded ( 0..23); same as %_H
%l 10 hour, space padded ( 1..12); same as %_I
%m 11 month (01..12)
%M 33 minute (00..59)
%n a newline
%N 258608657 nanoseconds (000000000..999999999)
%p AM locale's equivalent of either AM or PM; blank if not known
%P am like %p, but lower case
%q 4 quarter of year (1..4)
%r 10:33:55 AM locale's 12-hour clock time (e.g., 11:11:04 PM)
%R 10:33 24-hour hour and minute; same as %H:%M
%s 1637606035 seconds since 1970-01-01 00:00:00 UTC
%S 55 second (00..60)
%t a tab
%T 10:33:55 time; same as %H:%M:%S
%u 1 day of week (1..7); 1 is Monday
%U 47 week number of year, with Sunday as first day of week (00..53)
%V 47 ISO week number, with Monday as first day of week (01..53)
%w 1 day of week (0..6); 0 is Sunday
%W 47 week number of year, with Monday as first day of week (00..53)
%x 11/22/2021 locale's date representation (e.g., 12/31/99)
%X 10:33:55 AM locale's time representation (e.g., 23:13:48)
%y 21 last two digits of year (00..99)
%Y 2021 year
%z -0800 +hhmm numeric time zone (e.g., -0400)
%:z -08:00 +hh:mm numeric time zone (e.g., -04:00)
%::z -08:00:00 +hh:mm:ss numeric time zone (e.g., -04:00:00)
%:::z -08 numeric time zone with : to necessary precision (e.g., -04, +05:30)
%Z PST alphabetic time zone abbreviation (e.g., EDT)
BSD date
Show adjusted date/time
date -v-2m # two months ago
date -v+1H # one hour in the future
Convert epoch seconds to string date
date -r 1514308711