# Best Sortable Date and Time (start with the biggest go to smallest: year,month,day,hour,minute,second) date +%Y-%m-%d-%H-%M-%S # ex: 2015-09-15-13-28-50 (which means Sept 15th 2009 at 1:28:50 pm) # or this format where its easy to spot which one is the date and which is the time date +d%Y-%m-%d-t%H-%M-%S # ex: d2015-09-15-h13-28-50 # Epoch Second (seconds since 1970/1/1 at midnight at UTC - timezone independent, so it doesn't matter what timezone your in, this second will always be the same - however even though its timezone independent your timezone has to be selected correctly - the first thing this does is convert current time to UTC time then the UTC time to seconds since 1970/1/1 00:00:00) date +%s # Convert epoch second to a date in current timezone # whats 12341234 seconds? (whats the date and time 12341234 seconds after the epoch) date -d@12341234 # Sat May 23 16:07:14 EDT 1970 date -d@0 # Wed Dec 31 19:00:00 EST 1969 # Convert epoch second to a date in UTC (add -u) date -d@12341234 -u # Sat May 23 20:07:14 UTC 1970 date -d@0 # Thu Jan 1 00:00:00 UTC 1970 (date and time of the epoch)
Read the date man page for more info. http://ss64.com/bash/date.html
Also the date –help output is very useful
# date --help Usage: date [OPTION]... [+FORMAT] or: date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]] Display the current time in the given FORMAT, or set the system date. -d, --date=STRING display time described by STRING, not `now' -f, --file=DATEFILE like --date once for each line of DATEFILE -r, --reference=FILE display the last modification time of FILE -R, --rfc-2822 output date and time in RFC 2822 format. Example: Mon, 07 Aug 2006 12:34:56 -0600 --rfc-3339=TIMESPEC output date and time in RFC 3339 format. TIMESPEC=`date', `seconds', or `ns' for date and time to the indicated precision. Date and time components are separated by a single space: 2006-08-07 12:34:56-06:00 -s, --set=STRING set time described by STRING -u, --utc, --universal print or set Coordinated Universal Time --help display this help and exit --version output version information and exit FORMAT controls the output. Interpreted sequences are: %% a literal % %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) %C century; like %Y, except omit last two digits (e.g., 20) %d day of month (e.g., 01) %D date; same as %m/%d/%y %e day of month, space padded; same as %_d %F full date; same as %Y-%m-%d %g last two digits of year of ISO week number (see %G) %G year of ISO week number (see %V); normally useful only with %V %h same as %b %H hour (00..23) %I hour (01..12) %j day of year (001..366) %k hour, space padded ( 0..23); same as %_H %l hour, space padded ( 1..12); same as %_I %m month (01..12) %M minute (00..59) %n a newline %N nanoseconds (000000000..999999999) %p locale's equivalent of either AM or PM; blank if not known %P like %p, but lower case %r locale's 12-hour clock time (e.g., 11:11:04 PM) %R 24-hour hour and minute; same as %H:%M %s seconds since 1970-01-01 00:00:00 UTC %S second (00..60) %t a tab %T time; same as %H:%M:%S %u day of week (1..7); 1 is Monday %U week number of year, with Sunday as first day of week (00..53) %V ISO week number, with Monday as first day of week (01..53) %w day of week (0..6); 0 is Sunday %W week number of year, with Monday as first day of week (00..53) %x locale's date representation (e.g., 12/31/99) %X locale's time representation (e.g., 23:13:48) %y last two digits of year (00..99) %Y year %z +hhmm numeric time zone (e.g., -0400) %:z +hh:mm numeric time zone (e.g., -04:00) %::z +hh:mm:ss numeric time zone (e.g., -04:00:00) %:::z numeric time zone with : to necessary precision (e.g., -04, +05:30) %Z alphabetic time zone abbreviation (e.g., EDT) By default, date pads numeric fields with zeroes. The following optional flags may follow `%': - (hyphen) do not pad the field _ (underscore) pad with spaces 0 (zero) pad with zeros ^ use upper case if possible # use opposite case if possible After any flags comes an optional field width, as a decimal number; then an optional modifier, which is either E to use the locale's alternate representations if available, or O to use the locale's alternate numeric symbols if available. Examples: Convert seconds since the epoch (1970-01-01 UTC) to a date $ date --date='@2147483647' Show the time on the west coast of the US (use tzselect(1) to find TZ) $ TZ='America/Los_Angeles' date Show the local time for 9AM next Friday on the west coast of the US $ date --date='TZ="America/Los_Angeles" 09:00 next Fri' Report date bugs to email@example.com GNU coreutils home page: <http://www.gnu.org/software/coreutils/> General help using GNU software: <http://www.gnu.org/gethelp/> Report date translation bugs to <http://translationproject.org/team/> For complete documentation, run: info coreutils 'date invocation'