Number of leap seconds Post: 302323041

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Top Forums UNIX for Dummies Questions & Answers Number of leap seconds Post 302323041 by jim mcnamara on Friday 5th of June 2009 07:59:22 AM

06-05-2009

Registered User

No. The standard for UNIX timekeeping does not include leap seconds.

NTP servers will report correct UTC values as leap seconds are inserted.
See:
NIST Time Scale Data Archive

Here is how I would do it - this assumes your system time is actually corrected by an ntp server.

1. calculate the Julian day for Jan 1, 1970 - call it day1

2. calculate the Julian day for today -- day2

There is code to do this on this forum - search for it. Julian days == number of days since Jan 1 4712 BCE

3. use the fact there are 86400 seconds in a day.

Code:

# this works at midnight 00:00:00 hh:mm:dd
time_t leapsec=time(NULL) - ( (day2 * 86400) - day1 * 86400) );

FYI as of this date - Jun 5 2009 - leapsec = 24

corrected by jmc

Last edited by jim mcnamara; 06-05-2009 at 04:34 PM.. Reason: I can't count.

jim mcnamara

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LEARN ABOUT PHP

cal_from_jd

CAL_FROM_JD(3)								 1							    CAL_FROM_JD(3)

cal_from_jd - Converts from Julian Day Count to a supported calendar

SYNOPSIS

       array cal_from_jd (int  $jd, int  $calendar)

DESCRIPTION

       cal_from_jd(3)  converts  the Julian day given in $jd into a date of the specified $calendar. Supported $calendar values are CAL_GREGORIAN,
       CAL_JULIAN, CAL_JEWISH and CAL_FRENCH.

PARAMETERS

	      o $jd
		- Julian day as integer

	      o $calendar
		- Calendar to convert to

RETURN VALUES

	Returns an array containing calendar information like month, day, year, day of week, abbreviated and full names of weekday and	month  and
       the date in string form "month/day/year".

EXAMPLES

       Example #1

	      cal_from_jd(3) example

	      <?php
	      $today = unixtojd(mktime(0, 0, 0, 8, 16, 2003));
	      print_r(cal_from_jd($today, CAL_GREGORIAN));
	      ?>

	      The above example will output:

	      Array
	      (
		  [date] => 8/16/2003
		  [month] => 8
		  [day] => 16
		  [year] => 2003
		  [dow] => 6
		  [abbrevdayname] => Sat
		  [dayname] => Saturday
		  [abbrevmonth] => Aug
		  [monthname] => August
	      )

SEE ALSO

       cal_to_jd(3), jdtofrench(3), jdtogregorian(3), jdtojewish(3), jdtojulian(3), jdtounix(3).

PHP Documentation Group 													    CAL_FROM_JD(3)