File: coreutils.info,  Node: Options for date,  Next: Examples of date,  Prev: Setting the time,  Up: date invocation

21.1.6 Options for ‘date’
-------------------------

The program accepts the following options.  Also see *note Common
options::.  Except for ‘-u’, these options are all GNU extensions to
POSIX.

   All options that specify the date to display are mutually exclusive.
I.e.: ‘--date’, ‘--file’, ‘--reference’, ‘--resolution’.

‘-d DATESTR’
‘--date=DATESTR’
     Display the date and time specified in DATESTR instead of the
     current date and time.  DATESTR can be in almost any common format.
     It can contain month names, time zones, ‘am’ and ‘pm’, ‘yesterday’,
     etc.  For example, ‘--date="2020-07-21 14:19:13.489392193 +0530"’
     specifies the instant of time that is 489,392,193 nanoseconds after
     July 21, 2020 at 2:19:13 PM in a time zone that is 5 hours and 30
     minutes east of UTC.
     Note: input currently must be in locale independent format.  E.g.,
     the LC_TIME=C below is needed to print back the correct date in
     many locales:
          date -d "$(LC_TIME=C date)"
     *Note Date input formats::.

‘--debug’
     Annotate the parsed date, display the effective time zone, and warn
     about potential misuse.

‘-f DATEFILE’
‘--file=DATEFILE’
     Parse each line in DATEFILE as with ‘-d’ and display the resulting
     date and time.  If DATEFILE is ‘-’, use standard input.  This is
     useful when you have many dates to process, because the system
     overhead of starting up the ‘date’ executable many times can be
     considerable.

‘-I[TIMESPEC]’
‘--iso-8601[=TIMESPEC]’
     Display the date using an ISO 8601 format, ‘%Y-%m-%d’.

     The argument TIMESPEC specifies the number of additional terms of
     the time to include.  It can be one of the following:
     ‘auto’
          Print just the date.  This is the default if TIMESPEC is
          omitted.  This is like the format ‘%Y-%m-%d’.

     ‘hours’
          Also print hours and time zone.  This is like the format
          ‘%Y-%m-%dT%H%:z’.

     ‘minutes’
          Also print minutes.  This is like the format
          ‘%Y-%m-%dT%H:%M%:z’.

     ‘seconds’
          Also print seconds.  This is like the format
          ‘%Y-%m-%dT%H:%M:%S%:z’.

     ‘ns’
          Also print nanoseconds.  This is like the format
          ‘%Y-%m-%dT%H:%M:%S,%N%:z’.

     This format is always suitable as input for the ‘--date’ (‘-d’) and
     ‘--file’ (‘-f’) options, regardless of the current locale.

‘-r FILE’
‘--reference=FILE’
     Display the date and time of the last modification of FILE, instead
     of the current date and time.

‘--resolution’
     Display the timestamp resolution instead of the time.  Current
     clock timestamps that are output by ‘date’ are integer multiples of
     the timestamp resolution.  With this option, the format defaults to
     ‘%s.%N’.  For example, if the clock resolution is 1 millisecond,
     the output is:

          0.001000000

‘-R’
‘--rfc-email’
     Display the date and time using the format ‘%a, %d %b %Y %H:%M:%S
     %z’, evaluated in the C locale so abbreviations are always in
     English.  For example:

          Mon, 09 Jul 2020 17:00:00 -0400

     This format conforms to Internet RFCs 5322
     (https://tools.ietf.org/search/rfc5322), 2822
     (https://tools.ietf.org/search/rfc2822) and 822
     (https://tools.ietf.org/search/rfc822), the current and previous
     standards for Internet email.  For compatibility with older
     versions of ‘date’, ‘--rfc-2822’ and ‘--rfc-822’ are aliases for
     ‘--rfc-email’.

‘--rfc-3339=TIMESPEC’
     Display the date using a format specified by Internet RFC 3339
     (https://tools.ietf.org/search/rfc3339).  This is like
     ‘--iso-8601’, except that a space rather than a ‘T’ separates dates
     from times, and a period rather than a comma separates seconds from
     subseconds.  This format is always suitable as input for the
     ‘--date’ (‘-d’) and ‘--file’ (‘-f’) options, regardless of the
     current locale.

     The argument TIMESPEC specifies how much of the time to include.
     It can be one of the following:

     ‘date’
          Print just the full-date, e.g., ‘2020-07-21’.  This is like
          the format ‘%Y-%m-%d’.

     ‘seconds’
          Print the full-date and full-time separated by a space, e.g.,
          ‘2020-07-21 04:30:37+05:30’.  The output ends with a numeric
          time-offset; here the ‘+05:30’ means that local time is five
          hours and thirty minutes east of UTC.  This is like the format
          ‘%Y-%m-%d %H:%M:%S%:z’.

     ‘ns’
          Like ‘seconds’, but also print nanoseconds, e.g., ‘2020-07-21
          04:30:37.998458565+05:30’.  This is like the format ‘%Y-%m-%d
          %H:%M:%S.%N%:z’.

‘-s DATESTR’
‘--set=DATESTR’
     Set the date and time to DATESTR.  See ‘-d’ above.  See also *note
     Setting the time::.

‘-u’
‘--utc’
‘--universal’
     Use Universal Time by operating as if the ‘TZ’ environment variable
     were set to the string ‘UTC0’.  UTC stands for Coordinated
     Universal Time, established in 1960.  Universal Time is often
     called “Greenwich Mean Time” (GMT) for historical reasons.
     Typically, systems ignore leap seconds and thus implement an
     approximation to UTC rather than true UTC.