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1 .\" $FreeBSD: src/usr.sbin/zic/zic.8,v 1.11.2.4 2003/03/11 22:31:35 trhodes Exp $
2 .\" $DragonFly: src/usr.sbin/zic/zic.8,v 1.5 2008/10/19 20:15:58 swildner Exp $
3 .Dd October 19, 2008
4 .Dt ZIC 8
5 .Os
6 .Sh NAME
7 .Nm zic
8 .Nd timezone compiler
9 .Sh SYNOPSIS
10 .Nm
11 .Op Fl Dsv
12 .Op Fl d Ar directory
13 .Op Fl g Ar group
14 .Op Fl L Ar leapsecondfilename
15 .Op Fl l Ar localtime
16 .Op Fl m Ar mode
17 .Op Fl p Ar posixrules
18 .Op Fl u Ar user
19 .Op Fl y Ar command
20 .Op Ar filename ...
21 .Sh DESCRIPTION
22 The
23 .Nm
24 utility reads text from the file(s) named on the command line
25 and creates the time conversion information files specified in this input.
26 If a
27 .Ar filename
28 is
29 .Em - ,
30 the standard input is read.
31 .Pp
32 The following options are available:
33 .Bl -tag -width indent
34 .It Fl D
35 Do not automatically create directories. If the input file(s) specify
36 an output file in a directory which does not already exist, the
37 default behavior is to attempt to create the directory. If
38 .Fl D
39 is specified,
40 .Nm
41 will instead error out immediately.
42 .It Fl d Ar directory
43 Create time conversion information files in the named directory rather than
44 in the standard directory named below.
45 .It Fl g Ar group
46 After creating each output file, change its group ownership to the
47 specified
48 .Ar group
49 (which can be either a name or a numeric group ID).
50 .It Fl L Ar leapsecondfilename
51 Read leap second information from the file with the given name.
52 If this option is not used,
53 no leap second information appears in output files.
54 .It Fl l Ar timezone
55 Use the given
56 .Ar time zone
57 as local time.
58 The
59 .Nm
60 utility will act as if the input contained a link line of the form
61 .Bd -literal -offset indent
62 .No "Link timezone localtime"
63 .Ed
64 (Note that this action has no effect on
65 .Dx ,
66 since the local time zone is specified in
67 .Pa /etc/localtime
68 and not
69 .Pa /usr/share/zoneinfo/localtime . )
70 .It Fl m Ar mode
71 After creating each output file, change its access mode to
72 .Ar mode .
73 Both numeric and alphabetic modes are accepted
74 (see
75 .Xr chmod 1 ) .
76 .It Fl p Ar timezone
77 Use the given
78 .Ar "time zone" Ns 's
79 rules when handling POSIX-format
80 time zone environment variables.
81 The
82 .Nm
83 utility will act as if the input contained a link line of the form
84 .Bd -literal -offset indent
85 .No "Link timezone posixrules"
86 .Ed
87 .It Fl u Ar user
88 After creating each output file, change its owner to
89 .Ar user
90 (which can be either a name or a numeric user ID).
91 .It Fl v
92 Complain if a year that appears in a data file is outside the range
93 of years representable by
94 .Xr time 3
95 values.
96 Also complain if a time of 24:00
97 (which cannot be handled by pre-1998 versions of
98 .Nm )
99 appears in the input.
100 .It Fl s
101 Limit time values stored in output files to values that are the same
102 whether they're taken to be signed or unsigned.
103 You can use this option to generate SVVS-compatible files.
104 .It Fl y Ar command
105 Use the given
106 .Ar command
107 rather than
108 .Em yearistype
109 when checking year types (see below).
110 .El
111 .Pp
112 Input lines are made up of fields.
113 Fields are separated from one another by any number of white space characters.
114 Leading and trailing white space on input lines is ignored.
115 An unquoted sharp character (#) in the input introduces a comment which extends
116 to the end of the line the sharp character appears on.
117 White space characters and sharp characters may be enclosed in double quotes
118 (") if they're to be used as part of a field.
119 Any line that is blank (after comment stripping) is ignored.
120 Non-blank lines are expected to be of one of three types:
121 rule lines, zone lines, and link lines.
122 .Pp
123 A rule line has the form:
124 .Dl "Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
125 For example:
126 .Dl "Rule US 1967 1973 \- Apr lastSun 2:00 1:00 D"
127 .Pp
128 The fields that make up a rule line are:
129 .Bl -tag -width "LETTER/S" -offset indent
130 .It NAME
131 Give the (arbitrary) name of the set of rules this rule is part of.
132 .It FROM
133 Give the first year in which the rule applies.
134 Any integer year can be supplied; the Gregorian calendar is assumed.
135 The word
136 .Em minimum
137 (or an abbreviation) means the minimum year representable as an integer.
138 The word
139 .Em maximum
140 (or an abbreviation) means the maximum year representable as an integer.
141 Rules can describe times that are not representable as time values,
142 with the unrepresentable times ignored; this allows rules to be portable
143 among hosts with differing time value types.
144 .It TO
145 Give the final year in which the rule applies.
146 In addition to
147 .Em minimum
148 and
149 .Em maximum
150 (as above),
151 the word
152 .Em only
153 (or an abbreviation)
154 may be used to repeat the value of the
155 .Em FROM
156 field.
157 .It TYPE
158 Give the type of year in which the rule applies.
159 If
160 .Em TYPE
161 is
162 .Em \-
163 then the rule applies in all years between
164 .Em FROM
165 and
166 .Em TO
167 inclusive.
168 If
169 .Em TYPE
170 is something else, then
171 .Nm
172 executes the command
173 .Li yearistype Ar year Ar type
174 to check the type of a year:
175 an exit status of zero is taken to mean that the year is of the given type;
176 an exit status of one is taken to mean that the year is not of the given type.
177 .It IN
178 Name the month in which the rule takes effect.
179 Month names may be abbreviated.
180 .It ON
181 Give the day on which the rule takes effect.
182 Recognized forms include:
183 .Pp
184 .Bl -tag -width lastSun -compact -offset indent
185 .It \&5
186 the fifth of the month
187 .It lastSun
188 the last Sunday in the month
189 .It lastMon
190 the last Monday in the month
191 .It Sun>=8
192 first Sunday on or after the eighth
193 .It Sun<=25
194 last Sunday on or before the 25th
195 .El
196 .Pp
197 Names of days of the week may be abbreviated or spelled out in full.
198 Note that there must be no spaces within the
199 .Em ON
200 field.
201 .It AT
202 Give the time of day at which the rule takes effect.
203 Recognized forms include:
204 .Pp
205 .Bl -tag -width "\&1:28:14" -offset indent -compact
206 .It 2
207 time in hours
208 .It 2:00
209 time in hours and minutes
210 .It 15:00
211 24-hour format time (for times after noon)
212 .It 1:28:14
213 time in hours, minutes, and seconds
214 .It -
215 equivalent to 0
216 .El
217 .Pp
218 where hour 0 is midnight at the start of the day,
219 and hour 24 is midnight at the end of the day.
220 Any of these forms may be followed by the letter
221 .Sq Li w
222 if the given time is local
223 .Dq "wall clock"
224 time,
225 .Sq Li s
226 if the given time is local
227 .Dq standard
228 time, or
229 .Sq Li u
230 (or
231 .Sq Li g
232 or
233 .Sq Li z )
234 if the given time is universal time;
235 in the absence of an indicator,
236 wall clock time is assumed.
237 .It SAVE
238 Give the amount of time to be added to local standard time when the rule is in
239 effect.
240 This field has the same format as the
241 .Em AT
242 field
243 (although, of course, the
244 .Sq Li w
245 and
246 .Sq Li s
247 suffixes are not used).
248 .It LETTER/S
249 Give the
250 .Dq "variable part"
251 (for example, the
252 .Dq S
253 or
254 .Dq D
255 in
256 .Dq EST
257 or
258 .Dq EDT )
259 of time zone abbreviations to be used when this rule is in effect.
260 If this field is
261 .Em \- ,
262 the variable part is null.
263 .El
264 .Pp
265 A zone line has the form:
266 .Dl "Zone NAME GMTOFF RULES/SAVE FORMAT [UNTILYEAR [MONTH [DAY [TIME]]]]"
267 For example:
268 .Dl "Zone Australia/Adelaide 9:30 Aus CST 1971 Oct 31 2:00"
269 The fields that make up a zone line are:
270 .Bl -tag -width indent
271 .It NAME
272 The name of the time zone.
273 This is the name used in creating the time conversion information file for the
274 zone.
275 .It GMTOFF
276 The amount of time to add to UTC to get standard time in this zone.
277 This field has the same format as the
278 .Em AT
279 and
280 .Em SAVE
281 fields of rule lines;
282 begin the field with a minus sign if time must be subtracted from UTC.
283 .It RULES/SAVE
284 The name of the rule(s) that apply in the time zone or,
285 alternately, an amount of time to add to local standard time.
286 If this field is
287 .Em \-
288 then standard time always applies in the time zone.
289 .It FORMAT
290 The format for time zone abbreviations in this time zone.
291 The pair of characters
292 .Em %s
293 is used to show where the
294 .Dq "variable part"
295 of the time zone abbreviation goes.
296 Alternately,
297 a slash (/)
298 separates standard and daylight abbreviations.
299 .It UNTILYEAR [MONTH [DAY [TIME]]]
300 The time at which the UTC offset or the rule(s) change for a location.
301 It is specified as a year, a month, a day, and a time of day.
302 If this is specified,
303 the time zone information is generated from the given UTC offset
304 and rule change until the time specified.
305 The month, day, and time of day have the same format as the IN, ON, and AT
306 fields of a rule; trailing fields can be omitted, and default to the
307 earliest possible value for the missing fields.
308 .Pp
309 The next line must be a
310 .Dq continuation
311 line; this has the same form as a zone line except that the
312 string
313 .Dq Zone
314 and the name are omitted, as the continuation line will
315 place information starting at the time specified as the
316 .Dq until
317 information in the previous line in the file used by the previous line.
318 Continuation lines may contain
319 .Dq until
320 information, just as zone lines do, indicating that the next line is a further
321 continuation.
322 .El
323 .Pp
324 A link line has the form
325 .Dl "Link LINK-FROM LINK-TO"
326 For example:
327 .Dl "Link Europe/Istanbul Asia/Istanbul"
328 The
329 .Em LINK-FROM
330 field should appear as the
331 .Em NAME
332 field in some zone line;
333 the
334 .Em LINK-TO
335 field is used as an alternate name for that zone.
336 .Pp
337 Except for continuation lines,
338 lines may appear in any order in the input.
339 .Pp
340 Lines in the file that describes leap seconds have the following form:
341 .Dl "Leap YEAR MONTH DAY HH:MM:SS CORR R/S"
342 For example:
343 .Dl "Leap 1974 Dec 31 23:59:60 + S"
344 The
345 .Em YEAR ,
346 .Em MONTH ,
347 .Em DAY ,
348 and
349 .Em HH:MM:SS
350 fields tell when the leap second happened.
351 The
352 .Em CORR
353 field
354 should be
355 .Dq +
356 if a second was added
357 or
358 .Dq -
359 if a second was skipped.
360 .\" There's no need to document the following, since it's impossible for more
361 .\" than one leap second to be inserted or deleted at a time.
362 .\" The C Standard is in error in suggesting the possibility.
363 .\" See Terry J Quinn, The BIPM and the accurate measure of time,
364 .\" Proc IEEE 79, 7 (July 1991), 894-905.
365 .\" or
366 .\" .q ++
367 .\" if two seconds were added
368 .\" or
369 .\" .q --
370 .\" if two seconds were skipped.
371 The
372 .Em R/S
373 field
374 should be (an abbreviation of)
375 .Dq Stationary
376 if the leap second time given by the other fields should be interpreted as UTC
377 or
378 (an abbreviation of)
379 .Dq Rolling
380 if the leap second time given by the other fields should be interpreted as
381 local wall clock time.
382 .Sh "EXTENDED EXAMPLE"
383 Here is an extended example of
384 .Nm
385 input, intended to illustrate many of its features.
386 .Bd -literal
387 # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
388 Rule Swiss 1940 only - Nov 2 0:00 1:00 S
389 Rule Swiss 1940 only - Dec 31 0:00 0 -
390 Rule Swiss 1941 1942 - May Sun>=1 2:00 1:00 S
391 Rule Swiss 1941 1942 - Oct Sun>=1 0:00 0
393 Rule EU 1977 1980 - Apr Sun>=1 1:00u 1:00 S
394 Rule EU 1977 only - Sep lastSun 1:00u 0 -
395 Rule EU 1978 only - Oct 1 1:00u 0 -
396 Rule EU 1979 1995 - Sep lastSun 1:00u 0 -
397 Rule EU 1981 max - Mar lastSun 1:00u 1:00 S
398 Rule EU 1996 max - Oct lastSun 1:00u 0 -
400 # Zone NAME GMTOFF RULES FORMAT UNTIL
401 Zone Europe/Zurich 0:34:08 - LMT 1848 Sep 12
402 0:29:44 - BMT 1894 Jun
403 1:00 Swiss CE%sT 1981
404 1:00 EU CE%sT
406 Link Europe/Zurich Switzerland
407 .Ed
408 .Pp
409 In this example, the zone is named Europe/Zurich but it has an alias
410 as Switzerland.
411 Zurich was 34 minutes and 8 seconds west of GMT until
412 1848-09-12 at 00:00, when the offset changed to 29 minutes and 44
413 seconds.
414 After 1894-06-01 at 00:00 Swiss daylight saving rules (defined
415 with lines beginning with
416 .Dq Rule Swiss )
417 apply, and the GMT offset became one hour.
418 From 1981 to the present, EU daylight saving rules have
419 applied, and the UTC offset has remained at one hour.
420 .Pp
421 In 1940, daylight saving time applied from November 2 at 00:00 to
422 December 31 at 00:00.
423 In 1941 and 1942, daylight saving time applied
424 from the first Sunday in May at 02:00 to the first Sunday in October
425 at 00:00.
426 The pre-1981 EU daylight-saving rules have no effect
427 here, but are included for completeness.
428 Since 1981, daylight
429 saving has begun on the last Sunday in March at 01:00 UTC.
430 Until 1995 it ended the last Sunday in September at 01:00 UTC,
431 but this changed to the last Sunday in October starting in 1996.
432 .Pp
433 For purposes of
434 display,
435 .Dq LMT
436 and
437 .Dq BMT
438 were initially used, respectively.
439 Since
440 Swiss rules and later EU rules were applied, the display name for the
441 timezone has been CET for standard time and CEST for daylight saving
442 time.
443 .Sh NOTES
444 For areas with more than two types of local time,
445 you may need to use local standard time in the
446 .Em AT
447 field of the earliest transition time's rule to ensure that
448 the earliest transition time recorded in the compiled file is correct.
449 .Pp
450 If,
451 for a particular zone,
452 a clock advance caused by the start of daylight saving
453 coincides with and is equal to
454 a clock retreat caused by a change in UTC offset,
455 .Nm
456 produces a single transition to daylight saving at the new UTC offset
457 (without any change in wall clock time).
458 To get separate transitions
459 use multiple zone continuation lines
460 specifying transition instants using universal time.
461 .Sh FILES
462 .Bl -tag -width ".Pa /usr/share/zoneinfo" -compact
463 .It Pa /usr/share/zoneinfo
464 standard directory used for created files
465 .El
466 .Sh "SEE ALSO"
467 .Xr ctime 3 ,
468 .Xr tzfile 5 ,
469 .Xr zdump 8
470 .\" @(#)zic.8 8.4