1ZIC(8)                    Linux System Administration                   ZIC(8)
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NAME

6       zic - timezone compiler
7

SYNOPSIS

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

13       The  zic  program reads text from the file(s) named on the command line
14       and creates the time conversion information  files  specified  in  this
15       input.  If a filename is -, standard input is read.
16
17       These options are available:
18
19       -d directory
20              Create  time conversion information files in the named directory
21              rather than in the standard directory named below.
22
23       -l timezone
24              Use the given timezone as local time.  zic will act  as  if  the
25              input contained a link line of the form
26
27            Link timezone       localtime
28
29       -p timezone
30              Use  the given timezone's rules when handling POSIX-format time‐
31              zone environment variables.  zic will act as if the  input  con‐
32              tained a link line of the form
33
34            Link timezone       posixrules
35
36       -L leapsecondfilename
37              Read  leap second information from the file with the given name.
38              If this option is not used, no leap second  information  appears
39              in output files.
40
41       -v     Complain  if  a  year that appears in a data file is outside the
42              range of years representable by time(2) values.
43
44       -s     Limit time values stored in output files to values that are  the
45              same  whether  they're  taken to be signed or unsigned.  You can
46              use this option to generate SVVS-compatible files.
47
48       -y command
49              Use the given command rather than yearistype when checking  year
50              types (see below).
51
52       Input  lines  are  made  up  of  fields.  Fields are separated from one
53       another by any number of white space characters.  Leading and  trailing
54       white space on input lines is ignored.  An unquoted sharp character (#)
55       in the input introduces a comment which extends to the end of the  line
56       the sharp character appears on.  White space characters and sharp char‐
57       acters may be enclosed in double quotes (") if they're to  be  used  as
58       part  of  a field.  Any line that is blank (after comment stripping) is
59       ignored.  Nonblank lines are expected to be of one of three types: rule
60       lines, zone lines, and link lines.
61
62       A rule line has the form
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64       Rule  NAME  FROM  TO    TYPE  IN   ON       AT    SAVE  LETTER/S
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66       For example:
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68       Rule  US    1967  1973  -     Apr  lastSun  2:00  1:00  D
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70       The fields that make up a rule line are:
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72       NAME    Gives  the  (arbitrary)  name  of the set of rules this rule is
73               part of.
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75       FROM    Gives the first year in which the rule  applies.   Any  integer
76               year  can  be supplied; the Gregorian calendar is assumed.  The
77               word minimum (or an abbreviation) means the minimum year repre‐
78               sentable  as an integer.  The word maximum (or an abbreviation)
79               means the maximum year representable as an integer.  Rules  can
80               describe  times that are not representable as time values, with
81               the unrepresentable times ignored; this allows rules to be por‐
82               table among hosts with differing time value types.
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84       TO      Gives the final year in which the rule applies.  In addition to
85               minimum and maximum (as above), the word only (or an  abbrevia‐
86               tion) may be used to repeat the value of the FROM field.
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88       TYPE    Gives  the  type of year in which the rule applies.  If TYPE is
89               -, then the rule applies in  all  years  between  FROM  and  TO
90               inclusive.   If  TYPE  is something else, then zic executes the
91               command
92                    yearistype year type
93               to check the type of a year: an exit status of zero is taken to
94               mean  that the year is of the given type; an exit status of one
95               is taken to mean that the year is not of the given type.
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97       IN      Names the month in which the rule takes  effect.   Month  names
98               may be abbreviated.
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100       ON      Gives the day on which the rule takes effect.  Recognized forms
101               include:
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103       5        the fifth of the month
104       lastSun  the last Sunday in the month
105       lastMon  the last Monday in the month
106       Sun>=8   first Sunday on or after the eighth
107       Sun<=25  last Sunday on or before the 25th
108
109       Names of days of the week may be abbreviated or spelled  out  in  full.
110       Note that there must be no spaces within the ON field.
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112       AT     Gives  the  time  of day at which the rule takes effect.  Recog‐
113              nized forms include:
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115       2        time in hours
116       2:00     time in hours and minutes
117       15:00    24-hour format time (for times after noon)
118       1:28:14  time in hours, minutes, and seconds
119       -        equivalent to 0
120
121       where hour 0 is midnight at the start of the day, and hour 24  is  mid‐
122       night at the end of the day.  Any of these forms may be followed by the
123       letter w if the given time is local "wall clock" time, s if  the  given
124       time  is  local  "standard" time, or u (or g or z) if the given time is
125       universal time; in the absence of an  indicator,  wall  clock  time  is
126       assumed.
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128       SAVE   Gives the amount of time to be added to local standard time when
129              the rule is in effect.  This field has the same format as the AT
130              field (although, of course, the w and s suffixes are not used).
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132       LETTER/S
133              Gives  the "variable part" (for example, the "S" or "D" in "EST"
134              or "EDT") of timezone abbreviations to be used when this rule is
135              in effect.  If this field is -, the variable part is null.
136
137       A zone line has the form
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139            Zone  NAME                UTCOFF  RULES/SAVE  FORMAT  [UNTIL]
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141       For example:
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143            Zone  Australia/Adelaide  9:30    Aus         CST     1971 Oct 31 2:00
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145       The fields that make up a zone line are:
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147       NAME  The  name of the timezone.  This is the name used in creating the
148             time conversion information file for the zone.
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150       UTCOFF
151             The amount of time to add to UTC to get  standard  time  in  this
152             zone.   This  field has the same format as the AT and SAVE fields
153             of rule lines; begin the field with a minus sign if time must  be
154             subtracted from UTC.
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156       RULES/SAVE
157             The  name  of  the  rule(s) that apply in the timezone or, alter‐
158             nately, an amount of time to add to local standard time.  If this
159             field is -, then standard time always applies in the timezone.
160
161       FORMAT
162             The format for timezone abbreviations in this timezone.  The pair
163             of characters %s is used to show where the "variable part" of the
164             timezone  abbreviation  goes.  Alternately, a slash (/) separates
165             standard and daylight abbreviations.
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167       UNTIL The time at which the UTC offset or  the  rule(s)  change  for  a
168             location.   It is specified as a year, a month, a day, and a time
169             of day.  If this is specified, the timezone information is gener‐
170             ated  from  the  given  UTC offset and rule change until the time
171             specified.  The month, day, and time of day have the same  format
172             as  the IN, ON, and AT columns of a rule; trailing columns can be
173             omitted, and default to the earliest possible value for the miss‐
174             ing columns.
175
176             The  next  line  must be a "continuation" line; this has the same
177             form as a zone line except that the string "Zone"  and  the  name
178             are  omitted,  as  the  continuation  line will place information
179             starting at the time specified as the UNTIL field in the previous
180             line  in  the file used by the previous line.  Continuation lines
181             may contain an UNTIL field, just as  zone  lines  do,  indicating
182             that the next line is a further continuation.
183
184       A link line has the form
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186            Link  LINK-FROM        LINK-TO
187
188       For example:
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190            Link  Europe/Istanbul  Asia/Istanbul
191
192       The  LINK-FROM field should appear as the NAME field in some zone line;
193       the LINK-TO field is used as an alternate name for that zone.
194
195       Except for continuation lines, lines may appear in  any  order  in  the
196       input.
197
198       Lines in the file that describes leap seconds have the following form:
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200       Leap  YEAR  MONTH  DAY  HH:MM:SS  CORR  R/S
201
202       For example:
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204       Leap  1974  Dec    31   23:59:60  +     S
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206       The  YEAR,  MONTH,  DAY,  and HH:MM:SS fields tell when the leap second
207       happened.  The CORR field should be "+" if a second was added or "-" if
208       a  second  was  skipped.   The R/S field should be (an abbreviation of)
209       "Stationary" if the leap second time given by the other  fields  should
210       be  interpreted  as  UTC  or (an abbreviation of) "Rolling" if the leap
211       second time given by the other fields should be  interpreted  as  local
212       wall clock time.
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FILES

215       /usr/local/etc/zoneinfo
216              Standard directory used for created files.
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NOTES

219       For  areas  with more than two types of local time, you may need to use
220       local standard time in the AT field of the earliest  transition  time's
221       rule  to  ensure that the earliest transition time recorded in the com‐
222       piled file is correct.
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SEE ALSO

225       tzfile(5), zdump(8)
226

COLOPHON

228       This page is part of release 4.16 of the Linux  man-pages  project.   A
229       description  of  the project, information about reporting bugs, and the
230       latest    version    of    this    page,    can     be     found     at
231       https://www.kernel.org/doc/man-pages/.
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235                                  2010-02-25                            ZIC(8)
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