{
    "mode": "man",
    "parameter": "zdump",
    "section": "8",
    "url": "https://www.chedong.com/phpMan.php/man/zdump/8/json",
    "generated": "2026-05-30T07:08:22Z",
    "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": "",
            "subsections": [
                {
                    "name": "--version",
                    "content": "Output version information and exit.\n\n--help Output short usage message and exit.\n",
                    "long": "--version"
                },
                {
                    "name": "-i",
                    "content": "an interval-format description of the timezone.  See “INTERVAL FORMAT” below.\n",
                    "flag": "-i"
                },
                {
                    "name": "-v",
                    "content": "line,  print  the  time  at the lowest possible time value, the time one day after the\nlowest possible time value, the times both one second before and exactly at  each  de‐\ntected  time  discontinuity,  the  time at one day less than the highest possible time\nvalue, and the time at the highest possible time value.  Each line is followed by  is‐‐\ndst=D  where  D  is positive, zero, or negative depending on whether the given time is\ndaylight saving time, standard time, or an unknown time type, respectively.  Each line\nis  also followed by gmtoff=N if the given local time is known to be N seconds east of\nGreenwich.\n",
                    "flag": "-v"
                },
                {
                    "name": "-V -v",
                    "content": "output that is easier to compare to that of implementations with different time repre‐\nsentations.\n",
                    "flag": "-v"
                },
                {
                    "name": "-c",
                    "content": "Cut 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\nexclusive  and  the  upper is inclusive; for example, -c 1970,2070 selects transitions\nafter 1970-01-01 00:00:00 UTC and on or before 2070-01-01 00:00:00 UTC.   The  default\ncutoff is -500,2500.\n",
                    "flag": "-c"
                },
                {
                    "name": "-t",
                    "content": "Cut  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 exclusive\nand its upper bound is inclusive.\n",
                    "flag": "-t"
                }
            ]
        },
        "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 at twelve-hour\nintervals.  This works in all real-world cases; one can construct artificial time  zones  for\nwhich 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",
            "subsections": []
        },
        "COLOPHON": {
            "content": "This page is part of release 5.10 of the Linux  man-pages  project.   A  description  of  the\nproject,  information about reporting bugs, and the latest version of this page, can be found\nat https://www.kernel.org/doc/man-pages/.\n\n\n\n2020-04-27                                     ZDUMP(8)",
            "subsections": []
        }
    },
    "summary": "zdump - timezone dumper",
    "flags": [
        {
            "flag": "",
            "long": "--version",
            "arg": null,
            "description": "Output version information and exit. --help Output short usage message and exit."
        },
        {
            "flag": "-i",
            "long": null,
            "arg": null,
            "description": "an interval-format description of the timezone. See “INTERVAL FORMAT” below."
        },
        {
            "flag": "-v",
            "long": null,
            "arg": null,
            "description": "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 de‐ tected 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 is‐‐ dst=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."
        },
        {
            "flag": "-v",
            "long": null,
            "arg": null,
            "description": "output that is easier to compare to that of implementations with different time repre‐ sentations."
        },
        {
            "flag": "-c",
            "long": null,
            "arg": null,
            "description": "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 exclusive and the upper is inclusive; for example, -c 1970,2070 selects transitions after 1970-01-01 00:00:00 UTC and on or before 2070-01-01 00:00:00 UTC. The default cutoff is -500,2500."
        },
        {
            "flag": "-t",
            "long": null,
            "arg": null,
            "description": "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."
        }
    ],
    "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"
        }
    ]
}