1 .\" $FreeBSD: src/usr.sbin/zic/zic.8,v 1.11.2.4 2003/03/11 22:31:35 trhodes Exp $
13 .Op Fl L Ar leapsecondfilename
16 .Op Fl p Ar posixrules
23 utility reads text from the file(s) named on the command line
24 and creates the time conversion information files specified in this input.
29 the standard input is read.
31 The following options are available:
32 .Bl -tag -width indent
34 Do not automatically create directories. If the input file(s) specify
35 an output file in a directory which does not already exist, the
36 default behavior is to attempt to create the directory. If
40 will instead error out immediately.
42 Create time conversion information files in the named directory rather than
43 in the standard directory named below.
45 After creating each output file, change its group ownership to the
48 (which can be either a name or a numeric group ID).
49 .It Fl L Ar leapsecondfilename
50 Read leap second information from the file with the given name.
51 If this option is not used,
52 no leap second information appears in output files.
59 utility will act as if the input contained a link line of the form
60 .Bd -literal -offset indent
61 .No "Link timezone localtime"
63 (Note that this action has no effect on
65 since the local time zone is specified in
68 .Pa /usr/share/zoneinfo/localtime . )
70 After creating each output file, change its access mode to
72 Both numeric and alphabetic modes are accepted
78 rules when handling POSIX-format
79 time zone environment variables.
82 utility will act as if the input contained a link line of the form
83 .Bd -literal -offset indent
84 .No "Link timezone posixrules"
87 After creating each output file, change its owner to
89 (which can be either a name or a numeric user ID).
91 Complain if a year that appears in a data file is outside the range
92 of years representable by
95 Also complain if a time of 24:00
96 (which cannot be handled by pre-1998 versions of
100 Limit time values stored in output files to values that are the same
101 whether they're taken to be signed or unsigned.
102 You can use this option to generate SVVS-compatible files.
108 when checking year types (see below).
111 Input lines are made up of fields.
112 Fields are separated from one another by any number of white space characters.
113 Leading and trailing white space on input lines is ignored.
114 An unquoted sharp character (#) in the input introduces a comment which extends
115 to the end of the line the sharp character appears on.
116 White space characters and sharp characters may be enclosed in double quotes
117 (") if they're to be used as part of a field.
118 Any line that is blank (after comment stripping) is ignored.
119 Non-blank lines are expected to be of one of three types:
120 rule lines, zone lines, and link lines.
122 Names (such as month names) must be in English and are case insensitive.
123 Abbreviations, if used, must be unambiguous in context.
125 A rule line has the form:
126 .Dl "Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S"
128 .Dl "Rule US 1967 1973 \- Apr lastSun 2:00 1:00 D"
130 The fields that make up a rule line are:
131 .Bl -tag -width "LETTER/S" -offset indent
133 Give the (arbitrary) name of the set of rules this rule is part of.
135 Give the first year in which the rule applies.
136 Any integer year can be supplied; the Gregorian calendar is assumed.
139 (or an abbreviation) means the minimum year representable as an integer.
142 (or an abbreviation) means the maximum year representable as an integer.
143 Rules can describe times that are not representable as time values,
144 with the unrepresentable times ignored; this allows rules to be portable
145 among hosts with differing time value types.
147 Give the final year in which the rule applies.
156 may be used to repeat the value of the
160 Give the type of year in which the rule applies.
165 then the rule applies in all years between
172 is something else, then
175 .Li yearistype Ar year Ar type
176 to check the type of a year:
177 an exit status of zero is taken to mean that the year is of the given type;
178 an exit status of one is taken to mean that the year is not of the given type.
180 Name the month in which the rule takes effect.
181 Month names may be abbreviated.
183 Give the day on which the rule takes effect.
184 Recognized forms include:
186 .Bl -tag -width lastSun -compact -offset indent
188 the fifth of the month
190 the last Sunday in the month
192 the last Monday in the month
194 first Sunday on or after the eighth
196 last Sunday on or before the 25th
199 Names of days of the week may be abbreviated or spelled out in full.
200 Note that there must be no spaces within the
204 Give the time of day at which the rule takes effect.
205 Recognized forms include:
207 .Bl -tag -width "\&1:28:14" -offset indent -compact
211 time in hours and minutes
213 24-hour format time (for times after noon)
215 time in hours, minutes, and seconds
220 where hour 0 is midnight at the start of the day,
221 and hour 24 is midnight at the end of the day.
222 Any of these forms may be followed by the letter
224 if the given time is local
228 if the given time is local
236 if the given time is universal time;
237 in the absence of an indicator,
238 wall clock time is assumed.
240 Give the amount of time to be added to local standard time when the rule is in
242 This field has the same format as the
245 (although, of course, the
249 suffixes are not used).
261 of time zone abbreviations to be used when this rule is in effect.
264 the variable part is null.
267 A zone line has the form:
268 .Dl "Zone NAME GMTOFF RULES/SAVE FORMAT [UNTILYEAR [MONTH [DAY [TIME]]]]"
270 .Dl "Zone Australia/Adelaide 9:30 Aus CST 1971 Oct 31 2:00"
271 The fields that make up a zone line are:
272 .Bl -tag -width indent
274 The name of the time zone.
275 This is the name used in creating the time conversion information file for the
278 The amount of time to add to UTC to get standard time in this zone.
279 This field has the same format as the
283 fields of rule lines;
284 begin the field with a minus sign if time must be subtracted from UTC.
286 The name of the rule(s) that apply in the time zone or,
287 alternately, an amount of time to add to local standard time.
290 then standard time always applies in the time zone.
292 The format for time zone abbreviations in this time zone.
293 The pair of characters
295 is used to show where the
297 of the time zone abbreviation goes.
300 separates standard and daylight abbreviations.
301 .It UNTILYEAR [MONTH [DAY [TIME]]]
302 The time at which the UTC offset or the rule(s) change for a location.
303 It is specified as a year, a month, a day, and a time of day.
304 If this is specified,
305 the time zone information is generated from the given UTC offset
306 and rule change until the time specified.
307 The month, day, and time of day have the same format as the IN, ON, and AT
308 fields of a rule; trailing fields can be omitted, and default to the
309 earliest possible value for the missing fields.
311 The next line must be a
313 line; this has the same form as a zone line except that the
316 and the name are omitted, as the continuation line will
317 place information starting at the time specified as the
319 information in the previous line in the file used by the previous line.
320 Continuation lines may contain
322 information, just as zone lines do, indicating that the next line is a further
326 A link line has the form
327 .Dl "Link LINK-FROM LINK-TO"
329 .Dl "Link Europe/Istanbul Asia/Istanbul"
332 field should appear as the
334 field in some zone line;
337 field is used as an alternate name for that zone.
339 Except for continuation lines,
340 lines may appear in any order in the input.
342 Lines in the file that describes leap seconds have the following form:
343 .Dl "Leap YEAR MONTH DAY HH:MM:SS CORR R/S"
345 .Dl "Leap 1974 Dec 31 23:59:60 + S"
352 fields tell when the leap second happened.
358 if a second was added
361 if a second was skipped.
362 .\" There's no need to document the following, since it's impossible for more
363 .\" than one leap second to be inserted or deleted at a time.
364 .\" The C Standard is in error in suggesting the possibility.
365 .\" See Terry J Quinn, The BIPM and the accurate measure of time,
366 .\" Proc IEEE 79, 7 (July 1991), 894-905.
369 .\" if two seconds were added
372 .\" if two seconds were skipped.
376 should be (an abbreviation of)
378 if the leap second time given by the other fields should be interpreted as UTC
382 if the leap second time given by the other fields should be interpreted as
383 local wall clock time.
384 .Sh "EXTENDED EXAMPLE"
385 Here is an extended example of
387 input, intended to illustrate many of its features.
389 # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
390 Rule Swiss 1940 only - Nov 2 0:00 1:00 S
391 Rule Swiss 1940 only - Dec 31 0:00 0 -
392 Rule Swiss 1941 1942 - May Sun>=1 2:00 1:00 S
393 Rule Swiss 1941 1942 - Oct Sun>=1 0:00 0
395 Rule EU 1977 1980 - Apr Sun>=1 1:00u 1:00 S
396 Rule EU 1977 only - Sep lastSun 1:00u 0 -
397 Rule EU 1978 only - Oct 1 1:00u 0 -
398 Rule EU 1979 1995 - Sep lastSun 1:00u 0 -
399 Rule EU 1981 max - Mar lastSun 1:00u 1:00 S
400 Rule EU 1996 max - Oct lastSun 1:00u 0 -
402 # Zone NAME GMTOFF RULES FORMAT UNTIL
403 Zone Europe/Zurich 0:34:08 - LMT 1848 Sep 12
404 0:29:44 - BMT 1894 Jun
405 1:00 Swiss CE%sT 1981
408 Link Europe/Zurich Switzerland
411 In this example, the zone is named Europe/Zurich but it has an alias
413 Zurich was 34 minutes and 8 seconds west of GMT until
414 1848-09-12 at 00:00, when the offset changed to 29 minutes and 44
416 After 1894-06-01 at 00:00 Swiss daylight saving rules (defined
417 with lines beginning with
419 apply, and the GMT offset became one hour.
420 From 1981 to the present, EU daylight saving rules have
421 applied, and the UTC offset has remained at one hour.
423 In 1940, daylight saving time applied from November 2 at 00:00 to
424 December 31 at 00:00.
425 In 1941 and 1942, daylight saving time applied
426 from the first Sunday in May at 02:00 to the first Sunday in October
428 The pre-1981 EU daylight-saving rules have no effect
429 here, but are included for completeness.
431 saving has begun on the last Sunday in March at 01:00 UTC.
432 Until 1995 it ended the last Sunday in September at 01:00 UTC,
433 but this changed to the last Sunday in October starting in 1996.
440 were initially used, respectively.
442 Swiss rules and later EU rules were applied, the display name for the
443 timezone has been CET for standard time and CEST for daylight saving
446 For areas with more than two types of local time,
447 you may need to use local standard time in the
449 field of the earliest transition time's rule to ensure that
450 the earliest transition time recorded in the compiled file is correct.
453 for a particular zone,
454 a clock advance caused by the start of daylight saving
455 coincides with and is equal to
456 a clock retreat caused by a change in UTC offset,
458 produces a single transition to daylight saving at the new UTC offset
459 (without any change in wall clock time).
460 To get separate transitions
461 use multiple zone continuation lines
462 specifying transition instants using universal time.
464 .Bl -tag -width ".Pa /usr/share/zoneinfo" -compact
465 .It Pa /usr/share/zoneinfo
466 standard directory used for created files