{
    "mode": "man",
    "parameter": "zic",
    "section": "8",
    "url": "https://www.chedong.com/phpMan.php/man/zic/8/json",
    "generated": "2026-06-14T11:10:52Z",
    "synopsis": "zic [ option ... ] [ filename ... ]",
    "sections": {
        "NAME": {
            "content": "zic - timezone compiler\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "zic [ option ... ] [ filename ... ]\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "The  zic  program  reads text from the file(s) named on the command line and creates the time\nconversion information files specified in this input.  If a filename is “-”,  standard  input\nis read.\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": "-b",
                    "content": "Output  backward-compatibility  data as specified by bloat.  If bloat is fat, generate\nadditional data entries that work around potential bugs or incompatibilities in  older\nsoftware,  such  as  software  that mishandles the 64-bit generated data.  If bloat is\nslim, keep the output files small; this can help check for the bugs and incompatibili‐\nties.  Although the default is currently fat, this is intended to change in future zic\nversions, as software that mishandles the 64-bit data typically mishandles  timestamps\nafter  the  year 2038 anyway.  Also see the -r option for another way to shrink output\nsize.\n",
                    "flag": "-b"
                },
                {
                    "name": "-d",
                    "content": "Create time conversion information files in the named directory  rather  than  in  the\nstandard directory named below.\n",
                    "flag": "-d"
                },
                {
                    "name": "-l",
                    "content": "Use timezone as local time.  zic will act as if the input contained a link line of the\nform\n\nLink  timezone  localtime\n",
                    "flag": "-l"
                },
                {
                    "name": "-L",
                    "content": "Read leap second information from the file with the given name.  If this option is not\nused, no leap second information appears in output files.\n",
                    "flag": "-L"
                },
                {
                    "name": "-p",
                    "content": "Use  timezone's  rules when handling nonstandard TZ strings like \"EET-2EEST\" that lack\ntransition rules.  zic will act as if the input contained a link line of the form\n\nLink  timezone  posixrules\n\nThis feature is obsolete and poorly supported.  Among other things it  should  not  be\nused for timestamps after the year 2037, and it should not be combined with -b slim if\ntimezone's transitions are at standard time or Universal Time (UT)  instead  of  local\ntime.\n",
                    "flag": "-p"
                },
                {
                    "name": "-r",
                    "content": "Reduce  the  size of output files by limiting their applicability to timestamps in the\nrange from lo (inclusive) to hi (exclusive), where lo and hi are possibly-signed deci‐\nmal  counts  of seconds since the Epoch (1970-01-01 00:00:00 UTC).  Omitted counts de‐\nfault to extreme values.  For example, “zic -r @0” omits data  intended  for  negative\ntimestamps (i.e., before the Epoch), and “zic -r @0/@2147483648” outputs data intended\nonly for nonnegative timestamps that fit into 31-bit signed  integers.   On  platforms\nwith  GNU  date,  “zic -r @$(date +%s)” omits data intended for past timestamps.  Also\nsee the -b slim option for another way to shrink output size.\n",
                    "flag": "-r"
                },
                {
                    "name": "-t",
                    "content": "When creating local time information, put the configuration link  in  the  named  file\nrather than in the standard location.\n",
                    "flag": "-t"
                },
                {
                    "name": "-v",
                    "content": "The input specifies a link to a link.\n\nA year that appears in a data file is outside the range of representable years.\n\nA  time  of  24:00  or  more  appears in the input.  Pre-1998 versions of zic prohibit\n24:00, and pre-2007 versions prohibit times greater than 24:00.\n\nA rule goes past the start or end of the month.  Pre-2004  versions  of  zic  prohibit\nthis.\n\nA  time  zone  abbreviation uses a %z format.  Pre-2015 versions of zic do not support\nthis.\n\nA timestamp contains fractional seconds.  Pre-2018 versions  of  zic  do  not  support\nthis.\n\nThe  input  contains abbreviations that are mishandled by pre-2018 versions of zic due\nto a longstanding coding bug.  These abbreviations include “L” for  “Link”,  “mi”  for\n“min”, “Sa” for “Sat”, and “Su” for “Sun”.\n\nThe  output  file does not contain all the information about the long-term future of a\ntimezone, because the future cannot be summarized as an extended POSIX TZ string.  For\nexample,  as of 2019 this problem occurs for Iran's daylight-saving rules for the pre‐\ndicted future, as these rules are based on the Iranian calendar, which cannot be  rep‐\nresented.\n\nThe  output contains data that may not be handled properly by client code designed for\nolder zic output formats.  These compatibility issues affect  only  timestamps  before\n1970 or after the start of 2038.\n\nThe  output  file contains more than 1200 transitions, which may be mishandled by some\nclients.  The current reference client supports at  most  2000  transitions;  pre-2014\nversions of the reference client support at most 1200 transitions.\n\nA  time  zone abbreviation has fewer than 3 or more than 6 characters.  POSIX requires\nat least 3, and requires implementations to support at least 6.\n\nAn output file name contains a byte that is not an ASCII letter, “-”, “/”, or “”;  or\nit contains a file name component that contains more than 14 bytes or that starts with\n“-”.\n",
                    "flag": "-v"
                }
            ]
        },
        "FILES": {
            "content": "/etc/localtime\nDefault local timezone file.\n\n/usr/share/zoneinfo\nDefault timezone information directory.\n",
            "subsections": []
        },
        "EXTENDED EXAMPLE": {
            "content": "Here is an extended example of zic input, intended to illustrate many of  its  features.   In\nthis  example,  the EU rules are for the European Union and for its predecessor organization,\nthe European Communities.\n\n# Rule  NAME  FROM  TO    TYPE  IN   ON       AT    SAVE  LETTER/S\nRule    Swiss 1941  1942  -     May  Mon>=1   1:00  1:00  S\nRule    Swiss 1941  1942  -     Oct  Mon>=1   2:00  0     -\nRule    EU    1977  1980  -     Apr  Sun>=1   1:00u 1:00  S\nRule    EU    1977  only  -     Sep  lastSun  1:00u 0     -\nRule    EU    1978  only  -     Oct   1       1:00u 0     -\nRule    EU    1979  1995  -     Sep  lastSun  1:00u 0     -\nRule    EU    1981  max   -     Mar  lastSun  1:00u 1:00  S\nRule    EU    1996  max   -     Oct  lastSun  1:00u 0     -\n\n# Zone  NAME           STDOFF      RULES  FORMAT  [UNTIL]\nZone    Europe/Zurich  0:34:08     -      LMT     1853 Jul 16\n0:29:45.50  -      BMT     1894 Jun\n1:00        Swiss  CE%sT   1981\n1:00        EU     CE%sT\n\nLink    Europe/Zurich  Europe/Vaduz\n\nIn this example, the timezone is named Europe/Zurich but it has  an  alias  as  Europe/Vaduz.\nThis  example  says  that  Zurich was 34 minutes and 8 seconds east of UT until 1853-07-16 at\n00:00, when the legal offset was changed to 7°26′22.50″, which works out to  0:29:45.50;  zic\ntreats  this  by  rounding it to 0:29:46.  After 1894-06-01 at 00:00 the UT offset became one\nhour and Swiss daylight saving rules (defined with lines beginning with “Rule Swiss”)  apply.\nFrom  1981  to the present, EU daylight saving rules have applied, and the UTC offset has re‐\nmained at one hour.\n\nIn 1941 and 1942, daylight saving time applied from the first Monday in May at 01:00  to  the\nfirst Monday in October at 02:00.  The pre-1981 EU daylight-saving rules have no effect here,\nbut are included for completeness.  Since 1981, daylight saving has begun on the last  Sunday\nin  March  at  01:00 UTC.  Until 1995 it ended the last Sunday in September at 01:00 UTC, but\nthis changed to the last Sunday in October starting in 1996.\n\nFor purposes of display, “LMT” and “BMT” were  initially  used,  respectively.   Since  Swiss\nrules  and  later EU rules were applied, the time zone abbreviation has been CET for standard\ntime and CEST for daylight saving time.\n",
            "subsections": []
        },
        "NOTES": {
            "content": "For areas with more than two types of local time, you may need to use local standard time  in\nthe  AT  field  of the earliest transition time's rule to ensure that the earliest transition\ntime recorded in the compiled file is correct.\n\nIf, for a particular timezone, a clock advance caused by the start of daylight  saving  coin‐\ncides  with  and  is equal to a clock retreat caused by a change in UT offset, zic produces a\nsingle transition to daylight saving at the new UT offset without any change in  local  (wall\nclock)  time.   To  get  separate transitions use multiple zone continuation lines specifying\ntransition instants using universal time.\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "tzfile(5), zdump(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\n2020-08-13                                       ZIC(8)",
            "subsections": []
        }
    },
    "summary": "zic - timezone compiler",
    "flags": [
        {
            "flag": "",
            "long": "--version",
            "arg": null,
            "description": "Output version information and exit. --help Output short usage message and exit."
        },
        {
            "flag": "-b",
            "long": null,
            "arg": null,
            "description": "Output backward-compatibility data as specified by bloat. If bloat is fat, generate additional data entries that work around potential bugs or incompatibilities in older software, such as software that mishandles the 64-bit generated data. If bloat is slim, keep the output files small; this can help check for the bugs and incompatibili‐ ties. Although the default is currently fat, this is intended to change in future zic versions, as software that mishandles the 64-bit data typically mishandles timestamps after the year 2038 anyway. Also see the -r option for another way to shrink output size."
        },
        {
            "flag": "-d",
            "long": null,
            "arg": null,
            "description": "Create time conversion information files in the named directory rather than in the standard directory named below."
        },
        {
            "flag": "-l",
            "long": null,
            "arg": null,
            "description": "Use timezone as local time. zic will act as if the input contained a link line of the form Link timezone localtime"
        },
        {
            "flag": "-L",
            "long": null,
            "arg": null,
            "description": "Read leap second information from the file with the given name. If this option is not used, no leap second information appears in output files."
        },
        {
            "flag": "-p",
            "long": null,
            "arg": null,
            "description": "Use timezone's rules when handling nonstandard TZ strings like \"EET-2EEST\" that lack transition rules. zic will act as if the input contained a link line of the form Link timezone posixrules This feature is obsolete and poorly supported. Among other things it should not be used for timestamps after the year 2037, and it should not be combined with -b slim if timezone's transitions are at standard time or Universal Time (UT) instead of local time."
        },
        {
            "flag": "-r",
            "long": null,
            "arg": null,
            "description": "Reduce the size of output files by limiting their applicability to timestamps in the range from lo (inclusive) to hi (exclusive), where lo and hi are possibly-signed deci‐ mal counts of seconds since the Epoch (1970-01-01 00:00:00 UTC). Omitted counts de‐ fault to extreme values. For example, “zic -r @0” omits data intended for negative timestamps (i.e., before the Epoch), and “zic -r @0/@2147483648” outputs data intended only for nonnegative timestamps that fit into 31-bit signed integers. On platforms with GNU date, “zic -r @$(date +%s)” omits data intended for past timestamps. Also see the -b slim option for another way to shrink output size."
        },
        {
            "flag": "-t",
            "long": null,
            "arg": null,
            "description": "When creating local time information, put the configuration link in the named file rather than in the standard location."
        },
        {
            "flag": "-v",
            "long": null,
            "arg": null,
            "description": "The input specifies a link to a link. A year that appears in a data file is outside the range of representable years. A time of 24:00 or more appears in the input. Pre-1998 versions of zic prohibit 24:00, and pre-2007 versions prohibit times greater than 24:00. A rule goes past the start or end of the month. Pre-2004 versions of zic prohibit this. A time zone abbreviation uses a %z format. Pre-2015 versions of zic do not support this. A timestamp contains fractional seconds. Pre-2018 versions of zic do not support this. The input contains abbreviations that are mishandled by pre-2018 versions of zic due to a longstanding coding bug. These abbreviations include “L” for “Link”, “mi” for “min”, “Sa” for “Sat”, and “Su” for “Sun”. The output file does not contain all the information about the long-term future of a timezone, because the future cannot be summarized as an extended POSIX TZ string. For example, as of 2019 this problem occurs for Iran's daylight-saving rules for the pre‐ dicted future, as these rules are based on the Iranian calendar, which cannot be rep‐ resented. The output contains data that may not be handled properly by client code designed for older zic output formats. These compatibility issues affect only timestamps before 1970 or after the start of 2038. The output file contains more than 1200 transitions, which may be mishandled by some clients. The current reference client supports at most 2000 transitions; pre-2014 versions of the reference client support at most 1200 transitions. A time zone abbreviation has fewer than 3 or more than 6 characters. POSIX requires at least 3, and requires implementations to support at least 6. An output file name contains a byte that is not an ASCII letter, “-”, “/”, or “”; or it contains a file name component that contains more than 14 bytes or that starts with “-”."
        }
    ],
    "examples": [],
    "see_also": [
        {
            "name": "tzfile",
            "section": "5",
            "url": "https://www.chedong.com/phpMan.php/man/tzfile/5/json"
        },
        {
            "name": "zdump",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/zdump/8/json"
        }
    ]
}