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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 time at the lowest possible time value, the time one day after  the
              lowest  possible  time  value, the times both one second before and exactly at each
              detected time discontinuity, the time at one day less  than  the  highest  possible
              time value, and the time at the highest possible time value.  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 the times relative to the extreme time 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.   The  lower bound is exclusive and the upper is inclusive; for example, a
              loyear of 1970 excludes a transition occurring at 1970-01-01  00:00:00  UTC  but  a
              hiyear of 1970 includes the transition.  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
              exclusive and its upper bound is inclusive.

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"
         -          -          -10:31:26  LMT
         1896-01-13 12:01:26   -10:30     HST
         1933-04-30 03         -09:30     HDT        1
         1933-05-21 11         -10:30     HST
         1942-02-09 03         -09:30     HDT        1
         1945-09-30 01         -10:30     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"
         -          -          +03:12:12  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 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)

COLOPHON

       This page is part of release 5.02 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at https://www.kernel.org/doc/man-pages/.

                                            2019-03-06                                   ZDUMP(8)