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ZDUMP(8)		FreeBSD	System Manager's Manual		      ZDUMP(8)

     zdump -- timezone dumper

     zdump [--help] [--version]	[-ivV] [-c [loyear,]hiyear] [-t
	   [lotime,]hitime] [timezone ...]

     The zdump program prints the current time in each timezone	named on the
     command line.

     The following options are available:

	     Output version information	and exit.

     --help  Output short usage	message	and exit.

     -i	     Output a description of time intervals.  For each timezone	on the
	     command line, output an interval-format description of the	time-
	     zone.  See	INTERVAL FORMAT	below.

     -v	     Output a verbose description of time intervals.  For each
	     timezone on the command line, print the times at the two extreme
	     time values, the times (if	present) at and	just beyond the	bound-
	     aries of years that localtime(3) and gmtime(3) can	represent, and
	     the times both one	second before and exactly at each detected
	     time discontinuity.  Each line is followed	by isdst=D where D is
	     positive, zero, or	negative depending on whether the given	time
	     is	daylight saving	time, standard time, or	an unknown time	type,
	     respectively.  Each line is also followed by gmtoff=N if the
	     given local time is known to be N seconds east of Greenwich.

     -V	     Like -v, except omit output concerning extreme time and year val-
	     ues.  This	generates output that is easier	to compare to that of
	     implementations with different time representations.

     -c	[loyear,]hiyear
	     Cut off interval output at	the given year(s).  Cutoff times are
	     computed using the	proleptic Gregorian calendar with year 0 and
	     with Universal Time (UT) ignoring leap seconds.  Cutoffs are at
	     the start of each year, where the lower-bound timestamp is	inclu-
	     sive and the upper	is exclusive; for example, `-c 1970,2070' se-
	     lects transitions on or after 1970-01-01 00:00:00 UTC and before
	     2070-01-01	00:00:00 UTC.  The default cutoff is `-500,2500'.

     -t	[lotime,]hitime
	     Cut off interval output at	the given time(s), given in decimal
	     seconds since 1970-01-01 00:00:00 Coordinated Universal Time
	     (UTC).  The timezone determines whether the count includes	leap
	     seconds.  As with -c, the cutoff's	lower bound is inclusive and
	     its upper bound is	exclusive.

     The interval format is a compact text representation that is intended to
     be	both human- and	machine-readable.  It consists of an empty line, then
     a line "TZ=string"	where string is	a double-quoted	string giving the
     timezone, a second	line "	interval" describing the time interval before
     the first transition if any, and zero or more following lines "date time
     interval",	one line for each transition time and following	interval.
     Fields are	separated by single tabs.

     Dates are in `yyyy	- mm - dd' format and times are	in 24-hour `hh : mm :
     ss' format	where `hh <24'.	 Times are in local time immediately after the
     transition.  A time interval description consists of a UT offset in
     signed `+-	hhmmss'	format,	a time zone abbreviation, and an isdst flag.
     An	abbreviation that equals the UT	offset is omitted; other abbreviations
     are double-quoted strings unless they consist of one or more alphabetic
     characters.  An isdst flag	is omitted for standard	time, and otherwise is
     a decimal integer that is unsigned	and positive (typically	1) for day-
     light saving time and negative for	unknown.

     In	times and in UT	offsets	with absolute value less than 100 hours, the
     seconds are omitted if they are zero, and the minutes are also omitted if
     they are also zero.  Positive UT offsets are east of Greenwich.  The UT
     offset 00 denotes a UT placeholder	in areas where the actual offset is
     unspecified; by convention, this occurs when the UT offset	is zero	and
     the time zone abbreviation	begins with "-"	or is "zzz".

     In	double-quoted strings, escape sequences	represent unusual characters.
     The escape	sequences are \s for space, and	\", \\,	\f, \n,	\r, \t,	and \v
     with their	usual meaning in the C programming language.  E.g., the	dou-
     ble-quoted	string "CET\s\"\\" represents the character sequence CET "\.

     Here is an	example	of the output, with the	leading	empty line omitted.
     (This example is shown with tab stops set far enough apart	so that	the
     tabbed columns line up.)

	   -	   -	   -103126 LMT
	   1896-01-13	   12:01:26	   -1030   HST
	   1933-04-30	   03	   -0930   HDT	   1
	   1933-05-21	   11	   -1030   HST
	   1942-02-09	   03	   -0930   HWT	   1
	   1945-08-14	   13:30   -0930   HPT	   1
	   1945-09-30	   01	   -1030   HST
	   1947-06-08	   02:30   -10	   HST

     Here, local time begins 10	hours, 31 minutes and 26 seconds west of UT,
     and is a standard time abbreviated	LMT.  Immediately after	the first
     transition, the date is 1896-01-13	and the	time is	12:01:26, and the fol-
     lowing time interval is 10.5 hours	west of	UT, a standard time abbrevi-
     ated HST.	Immediately after the second transition, the date is
     1933-04-30	and the	time is	03:00:00 and the following time	interval is
     9.5 hours west of UT, is abbreviated HDT, and is daylight saving time.
     Immediately after the last	transition the date is 1947-06-08 and the time
     is	02:30:00, and the following time interval is 10	hours west of UT, a
     standard time abbreviated HST.

     Here are excerpts from another example:

	   -	   -	   +031212 LMT
	   1924-04-30	   23:47:48	   +03
	   1930-06-21	   01	   +04
	   1981-04-01	   01	   +05		   1
	   1981-09-30	   23	   +04
	   2014-10-26	   01	   +03
	   2016-03-27	   03	   +04

     This time zone is east of UT, so its UT offsets are positive.  Also, many
     of	its time zone abbreviations are	omitted	since they duplicate the text
     of	the UT offset.

     Time discontinuities are found by sampling	the results returned by
     localtime(3) at twelve-hour intervals.  This works	in all real-world
     cases; one	can construct artificial time zones for	which this fails.

     In	the -v and -V output, "UT" denotes the value returned by gmtime(3),
     which uses	UTC for	modern timestamps and some other UT flavor for time-
     stamps that predate the introduction of UTC.  No attempt is currently
     made to have the output use "UTC" for newer and "UT" for older time-
     stamps, partly because the	exact date of the introduction of UTC is prob-

     tzfile(5),	zic(8)

FreeBSD	13.0		       December	15, 2022		  FreeBSD 13.0


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