ZIC(8) | System Manager's Manual | ZIC(8) |
zic | [--version] [-d directory] [-L leapsecondfilename] [-l localtime] [-p posixrules] [-s] [-v] [-y command] [Filename ...] |
These options are available:
Link timezone localtime
Link timezone posixrules
Input files should be text files, that is, they should be a series of zero or more lines, each ending in a newline byte and containing at most 511 bytes, and without any NUL bytes. The input text's encoding is typically UTF-8 or ASCII; it should have a unibyte representation for the POSIX Portable Character Set (PPCS) http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap06.html and the encoding's non-unibyte characters should consist entirely of non-PPCS bytes. Non-PPCS characters typically occur only in comments: although output file names and time zone abbreviations can contain nearly any character, other software will work better if these are limited to the restricted syntax described under the [v] option.
Input lines are made up of fields. Fields are separated from one another by one or more white space characters. The white space characters are space, form feed, carriage return, newline, tab, and vertical tab. 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.
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
For example:Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
The fields that make up a rule line are:Rule US 1967 1973 - Apr lastSun 2:00 1:00 D
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.
A zone line has the form
For example:Zone NAME GMTOFF RULES/SAVE FORMAT [UNTILYEAR [MONTH [DAY [TIME]]]]
The fields that make up a zone line are:Zone Australia/Adelaide 9:30 Aus AC%sT 1971 Oct 31 2:00
A link line has the form
For example:Link TARGET LINK-NAME
The TARGET field should appear as the NAME field in some zone line. The LINK-NAME field is used as an alternative name for that zone; it has the same syntax as a zone line's NAME field.Link Europe/Istanbul Asia/Istanbul
Except for continuation lines, lines may appear in any order in the input. However, the behavior is unspecified if multiple zone or link lines define the same name, or if the source of one link line is the target of another.
Lines in the file that describes leap seconds have the following form:
For example:Leap YEAR MONTH DAY HH:MM:SS CORR R/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 UTC or (an abbreviation of) “Rolling” if the leap second time given by the other fields should be interpreted as local wall clock time.Leap 1974 Dec 31 23:59:60 + S
# Rule | NAME | FROM | TO | TYPE | IN | ON | AT | SAVE | LETTER/S |
Rule | Swiss | 1941 | 1942 | - | May | Mon>=1 | 1:00 | 1:00 | S |
Rule | Swiss | 1941 | 1942 | - | Oct | Mon>=1 | 2:00 | 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/SAVE | FORMAT | UNTIL |
Zone | Europe/Zurich | 0:34:08 | - | LMT | 1853 Jul 16 |
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. This example says that Zurich was 34 minutes and 8 seconds west of UT until 1853-07-16 at 00:00, when the legal offset was changed to 7°26′22.50″; although this works out to 0:29:45.50, the input format cannot represent fractional seconds so it is rounded here. After 1894-06-01 at 00:00 Swiss daylight saving rules (defined with lines beginning with "Rule Swiss") apply, and the UT 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 1941 and 1942, daylight saving time applied from the first Monday in May at 01:00 to the first Monday in October at 02:00. 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, respectively. Since Swiss rules and later EU rules were applied, the display name for the time zone has been CET for standard time and CEST for daylight saving time.
If, for a particular zone, a clock advance caused by the start of daylight saving coincides with and is equal to a clock retreat caused by a change in UT offset, zic produces a single transition to daylight saving at the new UT offset (without any change in wall clock time). To get separate transitions use multiple zone continuation lines specifying transition instants using universal time.
Time stamps well before the Big Bang are silently omitted from the output. This works around bugs in software that mishandles large negative time stamps. Call it sour grapes, but pre-Big-Bang time stamps are physically suspect anyway. The pre-Big-Bang cutoff time is approximate and may change in future versions.
October 6, 2014 | NetBSD 7.1 |