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NAME

       zdump - timezone dumper

SYNOPSIS

       zdump [ option ... ] [ timezone ... ]

DESCRIPTION

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

OPTIONS

       --version
              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  timezone.   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 boundaries 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  values.   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
              inclusive and the upper is exclusive; for example, -c 1970,2070 selects 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.

INTERVAL FORMAT

       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 daylight 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 double-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.)

         TZ="Pacific/Honolulu"
         -           -         -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 following time interval is 10.5 hours west of UT, a standard
       time abbreviated 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:

         TZ="Europe/Astrakhan"
         -           -         +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.

LIMITATIONS

       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 timestamps that predate the introduction of
       UTC.   No  attempt  is  currently made to have the output use “UTC” for newer and “UT” for
       older timestamps, partly because the exact date of the introduction of UTC is problematic.

SEE ALSO

       tzfile(5), zic(8)