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zic(8)                    BSD System Manager's Manual                   zic(8)


NAME

     zic -- timezone compiler


SYNOPSIS

     zic [--version] [-Dsv] [-d directory] [-g group] [-L leapsecondfilename]
         [-l localtime] [-m mode] [-p posixrules] [-u user] [-y command]
         [filename ...]


DESCRIPTION

     The zic utility reads text from the file(s) named on the command line and
     creates the time conversion information files specified in this input.
     If a filename is -, the standard input is read.

     The following options are available:

     --version
             Output version information and exit.

     -D      Do not automatically create directories.  If the input file(s)
             specify an output file in a directory which does not already
             exist, the default behavior is to attempt to create the direc-
             tory.  If -D is specified, zic will instead error out immedi-
             ately.

     -d directory
             Create time conversion information files in the named directory
             rather than in the standard directory named below.

     -g group
             After creating each output file, change its group ownership to
             the specified group (which can be either a name or a numeric
             group ID).

     -L leapsecondfilename
             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.

     -l timezone
             Use the given time zone as local time.  The zic utility will act
             as if the input contained a link line of the form

                   Link timezone       localtime

             (Note that this action has no effect on FreeBSD, since the local
             time zone is specified in /etc/localtime and not
             /usr/share/zoneinfo/localtime.)

     -m mode
             After creating each output file, change its access mode to mode.
             Both numeric and alphabetic modes are accepted (see chmod(1)).

     -p timezone
             Use the given time zone's rules when handling POSIX-format time
             zone environment variables.  The zic utility will act as if the
             input contained a link line of the form

                   Link timezone       posixrules

     -u user
             After creating each output file, change its owner to user (which
             can be either a name or a numeric user ID).

     -v      Complain if a year that appears in a data file is outside the
             range of years representable by time(3) values.

     -s      Limit time values stored in output files to values that are the
             same whether they are taken to be signed or unsigned.  You can
             use this option to generate SVVS-compatible files.

     -y command
             Use the given command rather than yearistype when checking year
             types (see below).

     Input lines are made up of fields.  Fields are separated from one another
     by any number of white space characters.  Leading and trailing white
     space on input lines is ignored.  An unquoted sharp character (#) in the
     input introduces a comment which extends to the end of the line the sharp
     character appears on.  White space characters and sharp characters may be
     enclosed in double quotes (") if they are to be used as part of a field.
     Any line that is blank (after comment stripping) is ignored.  Non-blank
     lines are expected to be of one of three types: rule lines, zone lines,
     and link lines.

     Names (such as month names) must be in English and are case insensitive.
     Abbreviations, if used, must be unambiguous in context.

     A rule line has the form:
           Rule NAME FROM TO   TYPE IN   ON        AT   SAVE LETTER/S
     For example:
           Rule US   1967 1973 -    Apr  lastSun   2:00 1:00 D

     The fields that make up a rule line are:

           NAME      Give the (arbitrary) name of the set of rules this rule
                     is part of.

           FROM      Give the first year in which the rule applies.  Any inte-
                     ger year can be supplied; the Gregorian calendar is
                     assumed.  The word minimum (or an abbreviation) means the
                     minimum year representable as an integer.  The word
                     maximum (or an abbreviation) means the maximum year rep-
                     resentable as an integer.  Rules can describe times that
                     are not representable as time values, with the unrepre-
                     sentable times ignored; this allows rules to be portable
                     among hosts with differing time value types.

           TO        Give the final year in which the rule applies.  In addi-
                     tion to minimum and maximum (as above), the word only (or
                     an abbreviation) may be used to repeat the value of the
                     FROM field.

           TYPE      Give the type of year in which the rule applies.  If TYPE
                     is - then the rule applies in all years between FROM and
                     TO inclusive.  If TYPE is something else, then zic exe-
                     cutes the command yearistype year type to check the type
                     of a year: an exit status of zero is taken to mean that
                     the year is of the given type; an exit status of one is
                     taken to mean that the year is not of the given type.

           IN        Name the month in which the rule takes effect.  Month
                     names may be abbreviated.

           ON        Give the day on which the rule takes effect.  Recognized
                     forms include:

                           5        the fifth of the month
                           lastSun  the last Sunday in the month
                           lastMon  the last Monday in the month
                           Sun>=8   first Sunday on or after the eighth
                           Sun<=25  last Sunday on or before the 25th

                     Names of days of the week may be abbreviated or spelled
                     out in full.  Note that there must be no spaces within
                     the ON field.

           AT        Give the time of day at which the rule takes effect.
                     Recognized forms include:

                           2        time in hours
                           2:00     time in hours and minutes
                           15:00    24-hour format time (for times after noon)
                           1:28:14  time in hours, minutes, and seconds

                     where hour 0 is midnight at the start of the day, and
                     hour 24 is midnight at the end of the day.  Any of these
                     forms may be followed by the letter `w' if the given time
                     is local ``wall clock'' time, `s' if the given time is
                     local ``standard'' time, or `u' (or `g' or `z') if the
                     given time is universal time; in the absence of an indi-
                     cator, wall clock time is assumed.

           SAVE      Give the amount of time to be added to local standard
                     time when the rule is in effect.  This field has the same
                     format as the AT field (although, of course, the `w' and
                     `s' suffixes are not used).

           LETTER/S  Give the ``variable part'' (for example, the ``S'' or
                     ``D'' in ``EST'' or ``EDT'') of time zone abbreviations
                     to be used when this rule is in effect.  If this field is
                     -, the variable part is null.

     A zone line has the form:
           Zone NAME GMTOFF    RULES/SAVE     FORMAT    [UNTILYEAR [MONTH [DAY
           [TIME]]]]
     For example:
           Zone Australia/Adelaide  9:30 Aus  CST  1971 Oct 31 2:00
     The fields that make up a zone line are:

     NAME    The name of the time zone.  This is the name used in creating the
             time conversion information file for the zone.

     GMTOFF  The amount of time to add to UTC to get standard time in this
             zone.  This field has the same format as the AT and SAVE fields
             of rule lines; begin the field with a minus sign if time must be
             subtracted from UTC.

     RULES/SAVE
             The name of the rule(s) that apply in the time zone or, alter-
             nately, an amount of time to add to local standard time.  If this
             field is - then standard time always applies in the time zone.

     FORMAT  The format for time zone abbreviations in this time zone.  The
             pair of characters %s is used to show where the ``variable part''
             of the time zone abbreviation goes.  Alternately, a slash (/)
             separates standard and daylight abbreviations.

     UNTILYEAR [MONTH [DAY [TIME]]]
             The time at which the UTC offset or the rule(s) change for a
             location.  It is specified as a year, a month, a day, and a time
             of day.  If this is specified, the time zone information is gen-
             erated from the given UTC offset and rule change until the time
             specified.  The month, day, and time of day have the same format
             as the IN, ON, and AT fields of a rule; trailing fields can be
             omitted, and default to the earliest possible value for the miss-
             ing fields.

             The next line must be a ``continuation'' line; this has the same
             form as a zone line except that the string ``Zone'' and the name
             are omitted, as the continuation line will place information
             starting at the time specified as the until information in the
             previous line in the file used by the previous line.  Continua-
             tion lines may contain until information, just as zone lines do,
             indicating that the next line is a further continuation.

     A link line has the form
           Link LINK-FROM LINK-TO
     For example:
           Link Europe/Istanbul     Asia/Istanbul
     The LINK-FROM field should appear as the NAME field in some zone line;
     the LINK-TO field is used as an alternate name for that zone.

     Except for continuation lines, lines may appear in any order in the
     input.

     Lines in the file that describes leap seconds have the following form:
           Leap YEAR MONTH     DAY  HH:MM:SS  CORR R/S
     For example:
           Leap 1974 Dec  31   23:59:60  +    S
     The YEAR, MONTH, DAY, and HH:MM:SS fields tell when the leap second hap-
     pened.  The CORR field should be ``+'' if a second was added or ``-'' if
     a second was skipped.  The R/S field should be (an abbreviation of)
     ``Stationary'' if the leap second time given by the other fields should
     be interpreted as UTC or (an abbreviation of) ``Rolling'' if the leap
     second time given by the other fields should be interpreted as local wall
     clock time.


EXTENDED EXAMPLE

     Here is an extended example of zic input, intended to illustrate many of
     its features.

       # Rule  NAME  FROM  TO    TYPE  IN   ON       AT    SAVE  LETTER/S
       Rule    Swiss 1940  only  -     Nov  2        0:00  1:00  S
       Rule    Swiss 1940  only  -     Dec  31       0:00  0     -
       Rule    Swiss 1941  1942  -     May  Sun>=1   2:00  1:00  S
       Rule    Swiss 1941  1942  -     Oct  Sun>=1   0:00  0
       Rule    EU    1977  1980  -     Apr  Sun>=1   1:00u 1:00  S
       Rule    EU    1977  only  -     Sep  lastSun  1:00u 0     -
       Rule    EU    1978  only  -     Oct   1       1:00u 0     -
       Rule    EU    1979  1995  -     Sep  lastSun  1:00u 0     -
       Rule    EU    1981  max   -     Mar  lastSun  1:00u 1:00  S
       Rule    EU    1996  max   -     Oct  lastSun  1:00u 0     -

       # Zone  NAME           GMTOFF   RULES       FORMAT  UNTIL
       Zone    Europe/Zurich  0:34:08  -           LMT     1848 Sep 12
                              0:29:44  -           BMT     1894 Jun
                              1:00     Swiss       CE%sT   1981
                              1:00     EU          CE%sT

       Link    Europe/Zurich  Switzerland

     In this example, the zone is named Europe/Zurich but it has an alias as
     Switzerland.  Zurich was 34 minutes and 8 seconds west of GMT until
     1848-09-12 at 00:00, when the offset changed to 29 minutes and 44 sec-
     onds.  After 1894-06-01 at 00:00 Swiss daylight saving rules (defined
     with lines beginning with "Rule Swiss") apply, and the GMT offset became
     one hour.  From 1981 to the present, EU daylight saving rules have
     applied, and the UTC offset has remained at one hour.

     In 1940, daylight saving time applied from November 2 at 00:00 to Decem-
     ber 31 at 00:00.  In 1941 and 1942, daylight saving time applied from the
     first Sunday in May at 02:00 to the first Sunday in October at 00:00.
     The pre-1981 EU daylight-saving rules have no effect here, but are
     included for completeness.  Since 1981, daylight saving has begun on the
     last Sunday in March at 01:00 UTC.  Until 1995 it ended the last Sunday
     in September at 01:00 UTC, but this changed to the last Sunday in October
     starting in 1996.

     For purposes of display, "LMT" and "BMT" were initially used, respec-
     tively.  Since Swiss rules and later EU rules were applied, the display
     name for the timezone has been CET for standard time and CEST for day-
     light saving time.


NOTES

     For areas with more than two types of local time, you may need to use
     local standard time in the AT field of the earliest transition time's
     rule to ensure that the earliest transition time recorded in the compiled
     file is correct.

     If, for a particular zone, a clock advance caused by the start of day-
     light saving coincides with and is equal to a clock retreat caused by a
     change in UTC offset, zic produces a single transition to daylight saving
     at the new UTC offset (without any change in wall clock time).  To get
     separate transitions use multiple zone continuation lines specifying
     transition instants using universal time.


FILES

     /usr/share/zoneinfo  standard directory used for created files


SEE ALSO

     ctime(3), tzfile(5), zdump(8)

BSD                              June 20, 2004                             BSD

Mac OS X 10.13.1 - Generated Sat Nov 11 07:52:31 CST 2017
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