21.1.6 Options for date
The program accepts the following options. Also see Common options.
- ‘-d 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)"
See Date input formats.
- ‘-f 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
- Display the date using the 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:
- Print just the date. This is the default if timespec is omitted.
- Append the hour of the day to the date.
- Append the hours and minutes.
- Append the hours, minutes and seconds.
- Append the hours, minutes, seconds and nanoseconds.
If showing any time terms, then include the time zone using the format
- ‘-r file’
- Display the date and time of the last modification of file,
instead of the current date and time.
- 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.
Fri, 09 Sep 2005 13:51:39 -0700
This format conforms to
Internet RFCs 2822 and
current and previous standards for Internet email.
- Display the date using a format specified by
Internet RFC 3339. This is a subset of the ISO 8601
format, except that it also permits applications to use a space rather
than a ‘T’ to separate dates from times. Unlike the other
standard formats, RFC 3339 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:
- Print just the full-date, e.g., ‘2005-09-14’.
This is equivalent to the format ‘%Y-%m-%d’.
- 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’.
- Like ‘seconds’, but also print nanoseconds, e.g.,
This is equivalent to the format ‘%Y-%m-%d %H:%M:%S.%N%:z’.
- ‘-s datestr’
- Set the date and time to datestr. See -d above.
See also Setting the time.
- Use Coordinated Universal Time (UTC) by operating as if the
TZ environment variable were set to the string ‘UTC0’.
Universal Time is often called “Greenwich Mean Time” (GMT) for
Typically, systems ignore leap seconds and thus implement an
approximation to UTC rather than true UTC.