(coreutils.info)Examples of date

---

Prev: Options for date Up: date invocation

---

Enter node , (file) or (file)node

21.1.7 Examples of ‘date’
-------------------------

Here are a few examples.  Also see the documentation for the ‘-d’ option
in the previous section.

   • To print the date of the day before yesterday:

          date --date='2 days ago'

   • To print the date of the day three months and one day hence:

          date --date='3 months 1 day'

   • To print the day of year of Christmas in the current year:

          date --date='25 Dec' +%j

   • To print the current full month name and the day of the month:

          date '+%B %d'

     But this may not be what you want because for the first nine days
     of the month, the ‘%d’ expands to a zero-padded two-digit field,
     for example ‘date -d 1may '+%B %d'’ will print ‘May 01’.

   • To print a date without the leading zero for one-digit days of the
     month, you can use the (GNU extension) ‘-’ flag to suppress the
     padding altogether:

          date -d 1may '+%B %-d'

   • To print the current date and time in the format required by many
     non-GNU versions of ‘date’ when setting the system clock:

          date +%m%d%H%M%Y.%S

   • To set the system clock forward by two minutes:

          date --set='+2 minutes'

   • To print the date in Internet RFC 5322 format, use ‘date
     --rfc-email’.  Here is some example output:

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

   • To convert a date string to the number of seconds since the epoch
     (which is 1970-01-01 00:00:00 UTC), use the ‘--date’ option with
     the ‘%s’ format.  That can be useful in sorting and/or graphing
     and/or comparing data by date.  The following command outputs the
     number of the seconds since the epoch for the time two minutes
     after the epoch:

          date --date='1970-01-01 00:02:00 +0000' +%s
          120

     If you do not specify time zone information in the date string,
     ‘date’ uses your computer’s idea of the time zone when interpreting
     the string.  For example, if your computer’s time zone is that of
     Cambridge, Massachusetts, which was then 5 hours (i.e., 18,000
     seconds) behind UTC:

          # local time zone used
          date --date='1970-01-01 00:02:00' +%s
          18120

   • If you’re sorting or graphing dated data, your raw date values may
     be represented as seconds since the epoch.  But few people can look
     at the date ‘946684800’ and casually note “Oh, that’s the first
     second of the year 2000 in Greenwich, England.”

          date --date='2000-01-01 UTC' +%s
          946684800

     An alternative is to use the ‘--utc’ (‘-u’) option.  Then you may
     omit ‘UTC’ from the date string.  Although this produces the same
     result for ‘%s’ and many other format sequences, with a time zone
     offset different from zero, it would give a different result for
     zone-dependent formats like ‘%z’.

          date -u --date=2000-01-01 +%s
          946684800

     To convert such an unwieldy number of seconds back to a more
     readable form, use a command like this:

          # local time zone used
          date -d '1970-01-01 UTC 946684800 seconds' +"%Y-%m-%d %T %z"
          1999-12-31 19:00:00 -0500

     Or if you do not mind depending on the ‘@’ feature present since
     coreutils 5.3.0, you could shorten this to:

          date -d @946684800 +"%F %T %z"
          1999-12-31 19:00:00 -0500

     Often it is better to output UTC-relative date and time:

          date -u -d '1970-01-01 946684800 seconds' +"%Y-%m-%d %T %z"
          2000-01-01 00:00:00 +0000

   • Typically the seconds count omits leap seconds, but some systems
     are exceptions.  Because leap seconds are not predictable, the
     mapping between the seconds count and a future timestamp is not
     reliable on the atypical systems that include leap seconds in their
     counts.

     Here is how the two kinds of systems handle the leap second at
     2012-06-30 23:59:60 UTC:

          # Typical systems ignore leap seconds:
          date --date='2012-06-30 23:59:59 +0000' +%s
          1341100799
          date --date='2012-06-30 23:59:60 +0000' +%s
          date: invalid date '2012-06-30 23:59:60 +0000'
          date --date='2012-07-01 00:00:00 +0000' +%s
          1341100800

          # Atypical systems count leap seconds:
          date --date='2012-06-30 23:59:59 +0000' +%s
          1341100823
          date --date='2012-06-30 23:59:60 +0000' +%s
          1341100824
          date --date='2012-07-01 00:00:00 +0000' +%s
          1341100825