zic - time zone compiler

     zic [ -v ] [ -d directory ] [ -l localtime ]  [  -p  posixrules  ]  [  -L
     leapsecondfilename ] [ -s ] [ -y command ] [ filename ... ]

     Zic 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.

     These options are available:

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

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

                Link    timezone        localtime

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

                Link    timezone        posixrules

     -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.

     -v   Complain if a year that appears in a data file is outside the  range
          of years representable by time(2) values.

     -s   Limit time values stored in output files to values that are the same
          whether  they're  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're 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.

     A rule line has the form

     Rule    NAME    FROM    TO      TYPE    IN     ON         AT      SAVE

     For example:

     Rule    US      1967    1973    -       Apr    lastSun    2:00    1:00

     The fields that make up a rule line are:

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

     FROM    Gives the first year in which the rule applies.  Any integer 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 representable as an  integer.   Rules  can  describe
             times  that  are  not  representable  as  time  values,  with the
             unrepresentable times ignored; this allows rules to  be  portable
             among hosts with differing time value types.

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

     TYPE    Gives 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 executes 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      Names the month in which the rule takes effect.  Month names  may
             be abbreviated.

     ON      Gives the day on which the rule takes effect.   Recognized  forms

                   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      Gives 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

             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 indicator, wall clock time is assumed.

     SAVE    Gives 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).

             Gives 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

     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.

           The amount of time to add to GMT 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 GMT.

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

           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.

     UNTIL The time at which the GMT  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  generated
           from the given GMT offset and rule change until the time specified.

           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 field in the previous line in
           the file used by the previous line.  Continuation lines may contain
           an  UNTIL  field,  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

     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
     happened.  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 GMT or (an abbreviation of) "Rolling" if the  leap  second
     time  given by the other fields should be interpreted as local wall clock

     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.


     /usr/lib/zoneinfo        Standard directory used for created files

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