{ "mode": "man", "parameter": "zdump", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/zdump/8/json", "generated": "2026-08-13T23:38:26Z", "synopsis": "zdump [ option ... ] [ timezone ... ]", "sections": { "NAME": { "content": "zdump - timezone dumper\n", "subsections": [] }, "SYNOPSIS": { "content": "zdump [ option ... ] [ timezone ... ]\n", "subsections": [] }, "DESCRIPTION": { "content": "The zdump program prints the current time in each timezone named on the command line.\n", "subsections": [] }, "OPTIONS": { "content": "--version\nOutput version information and exit.\n\n--help Output short usage message and exit.\n\n-i Output a description of time intervals. For each timezone on the command line, output\nan interval-format description of the timezone. See “INTERVAL FORMAT” below.\n\n-v Output a verbose description of time intervals. For each timezone on the command\nline, print the times at the two extreme time values, the times (if present) at and\njust beyond the boundaries of years that localtime(3) and gmtime(3) can represent, and\nthe times both one second before and exactly at each detected time discontinuity.\nEach line is followed by isdst=D where D is positive, zero, or negative depending on\nwhether the given time is daylight saving time, standard time, or an unknown time\ntype, respectively. Each line is also followed by gmtoff=N if the given local time is\nknown to be N seconds east of Greenwich.\n\n-V Like -v, except omit output concerning extreme time and year values. This generates\noutput that is easier to compare to that of implementations with different time repre‐\nsentations.\n\n-c [loyear,]hiyear\nCut off interval output at the given year(s). Cutoff times are computed using the\nproleptic Gregorian calendar with year 0 and with Universal Time (UT) ignoring leap\nseconds. Cutoffs are at the start of each year, where the lower-bound timestamp is\ninclusive and the upper is exclusive; for example, -c 1970,2070 selects transitions on\nor after 1970-01-01 00:00:00 UTC and before 2070-01-01 00:00:00 UTC. The default cut‐\noff is -500,2500.\n\n-t [lotime,]hitime\nCut off interval output at the given time(s), given in decimal seconds since\n1970-01-01 00:00:00 Coordinated Universal Time (UTC). The timezone determines whether\nthe count includes leap seconds. As with -c, the cutoff's lower bound is inclusive\nand its upper bound is exclusive.\n", "subsections": [] }, "INTERVAL FORMAT": { "content": "The interval format is a compact text representation that is intended to be both human- and\nmachine-readable. It consists of an empty line, then a line “TZ=string” where string is a\ndouble-quoted string giving the timezone, a second line “- - interval” describing the time\ninterval before the first transition if any, and zero or more following lines “date time in‐\nterval”, one line for each transition time and following interval. Fields are separated by\nsingle tabs.\n\nDates are in yyyy-mm-dd format and times are in 24-hour hh:mm:ss format where hh<24. Times\nare in local time immediately after the transition. A time interval description consists of\na UT offset in signed ±hhmmss format, a time zone abbreviation, and an isdst flag. An abbre‐\nviation that equals the UT offset is omitted; other abbreviations are double-quoted strings\nunless they consist of one or more alphabetic characters. An isdst flag is omitted for stan‐\ndard time, and otherwise is a decimal integer that is unsigned and positive (typically 1) for\ndaylight saving time and negative for unknown.\n\nIn times and in UT offsets with absolute value less than 100 hours, the seconds are omitted\nif they are zero, and the minutes are also omitted if they are also zero. Positive UT off‐\nsets are east of Greenwich. The UT offset -00 denotes a UT placeholder in areas where the\nactual offset is unspecified; by convention, this occurs when the UT offset is zero and the\ntime zone abbreviation begins with “-” or is “zzz”.\n\nIn double-quoted strings, escape sequences represent unusual characters. The escape se‐\nquences are \\s for space, and \\\", \\\\, \\f, \\n, \\r, \\t, and \\v with their usual meaning in the\nC programming language. E.g., the double-quoted string “\"CET\\s\\\"\\\\\"” represents the charac‐\nter sequence “CET \"\\”.\n\nHere is an example of the output, with the leading empty line omitted. (This example is\nshown with tab stops set far enough apart so that the tabbed columns line up.)\n\nTZ=\"Pacific/Honolulu\"\n- - -103126 LMT\n1896-01-13 12:01:26 -1030 HST\n1933-04-30 03 -0930 HDT 1\n1933-05-21 11 -1030 HST\n1942-02-09 03 -0930 HWT 1\n1945-08-14 13:30 -0930 HPT 1\n1945-09-30 01 -1030 HST\n1947-06-08 02:30 -10 HST\n\nHere, local time begins 10 hours, 31 minutes and 26 seconds west of UT, and is a standard\ntime abbreviated LMT. Immediately after the first transition, the date is 1896-01-13 and the\ntime is 12:01:26, and the following time interval is 10.5 hours west of UT, a standard time\nabbreviated HST. Immediately after the second transition, the date is 1933-04-30 and the\ntime is 03:00:00 and the following time interval is 9.5 hours west of UT, is abbreviated HDT,\nand is daylight saving time. Immediately after the last transition the date is 1947-06-08\nand the time is 02:30:00, and the following time interval is 10 hours west of UT, a standard\ntime abbreviated HST.\n\nHere are excerpts from another example:\n\nTZ=\"Europe/Astrakhan\"\n- - +031212 LMT\n1924-04-30 23:47:48 +03\n1930-06-21 01 +04\n1981-04-01 01 +05 1\n1981-09-30 23 +04\n...\n2014-10-26 01 +03\n2016-03-27 03 +04\n\nThis time zone is east of UT, so its UT offsets are positive. Also, many of its time zone\nabbreviations are omitted since they duplicate the text of the UT offset.\n", "subsections": [] }, "LIMITATIONS": { "content": "Time discontinuities are found by sampling the results returned by localtime(3) at twelve-\nhour intervals. This works in all real-world cases; one can construct artificial time zones\nfor which this fails.\n\nIn the -v and -V output, “UT” denotes the value returned by gmtime(3), which uses UTC for\nmodern timestamps and some other UT flavor for timestamps that predate the introduction of\nUTC. No attempt is currently made to have the output use “UTC” for newer and “UT” for older\ntimestamps, partly because the exact date of the introduction of UTC is problematic.\n", "subsections": [] }, "SEE ALSO": { "content": "tzfile(5), zic(8)\n\nTime Zone Database zdump(8)", "subsections": [] } }, "summary": "zdump - timezone dumper", "flags": [], "examples": [], "see_also": [ { "name": "tzfile", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/tzfile/5/json" }, { "name": "zic", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/zic/8/json" } ] }