(coreutils.info)Options for date

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21.1.6 Options for ‘date’
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The program accepts the following options.  Also see Note: Common
options.

‘-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="2004-02-27 14:19:13.489392193 +0530"’
     specifies the instant of time that is 489,392,193 nanoseconds after
     February 27, 2004 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.

     ‘hours’
          Append the hour of the day to the date.

     ‘minutes’
          Append the hours and minutes.

     ‘seconds’
          Append the hours, minutes and seconds.

     ‘ns’
          Append the hours, minutes, seconds and nanoseconds.

     If showing any time terms, then include the time zone using the
     format ‘%: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.

‘-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:

          Fri, 09 Sep 2005 13:51:39 -0700

     This format conforms to Internet RFCs 5322
     (https://tools.ietf.org/search/rfc5322), 822
     (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.  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., ‘2005-09-14’.  This is
          equivalent to the format ‘%Y-%m-%d’.

     ‘seconds’
          Print the full-date and full-time separated by a space, e.g.,
          ‘2005-09-14 00:56:06+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 equivalent to
          the format ‘%Y-%m-%d %H:%M:%S%:z’.

     ‘ns’
          Like ‘seconds’, but also print nanoseconds, e.g., ‘2005-09-14
          00:56:06.998458565+05:30’.  This is equivalent to 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.