ZIC(8) | System Manager's Manual | ZIC(8) |
zic
—
zic |
[--version ] [--help ]
[-b ] [-d
directory] [-L
leapsecondfilename] [-l
localtime] [-p
posixrules] [-s ]
[-t file]
[-v ] [-y
command] [Filename ...] |
zic
program 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 -,
standard input is read.
--version
--help
-b
bloatfat
, generate additional data entries that work
around potential bugs or incompatibilities in older software, such as
software that mishandles the 64-bit generated data. If
bloat is slim
, keep the
output files small; this can help check for the bugs and
incompatibilities. Although the default is currently
fat
, this is intended to change in future
zic
versions, as software that mishandles the
64-bit data typically mishandles timestamps after the year 2038 anyway.
Also see the -r
option for another way to shrink
output size.-d
directory-l
timezonezic
will act as if the input contained a link line
of the form
Link timezone localtime
-L
leapsecondfilename-p
timezonezic
will act as if the input contained a link line
of the form
Link timezone posixrules
This feature is obsolete and poorly supported. Among other
things it should not be used for timestamps after the year 2037, and it
should not be combined with -b
slim if timezone's
transitions are at standard time or UT instead of local time.
-r
[@lo / [@hi]]-b
slim option for another
way to shrink output size.-t
file-v
zic
prohibit 24:00, and pre-2007 versions
prohibit times greater than 24:00.zic
prohibit this.%z
format.
Pre-2015 versions of zic
do not support
this.zic
do not support this.zic
due to a longstanding coding
bug. These abbreviations include “L” for
“Link”, “mi” for “min”,
“Sa” for “Sat”, and “Su” for
“Sun”.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. Nonblank lines are expected to be of one of three types: rule lines, zone lines, and link lines.
Names must be in English and are case insensitive. They appear in several contexts, and include month and weekday names and keywords such as “maximum”, “only”, “Rolling”, and “Zone”. A name can be abbreviated by omitting all but an initial prefix; any abbreviation must be unambiguous in context.
A rule line has the form
Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
For example:
Rule US 1967 1973 - Apr lastSun 2:00w 1:00d D
The fields that make up a rule line are:
zic
in which it could contain year
types.Names of days of the week may be abbreviated or spelled out in full. A weekday name (e.g., “Sunday”) or a weekday name preceded by “last” (e.g., “lastSunday”) may be abbreviated or spelled out in full. There must be no white space characters within the ON field. The “<=” and “>=” constructs can result in a day in the neighboring month; for example, the IN-ON combination “Oct Sun>=31” tands for the first Sunday on or after October 31, even if that Sunday occurs in November.
Although rounds times to the nearest integer second (breaking ties to the even integer), the fractions may be useful to other applications requiring greater precision. The source format does not specify any maximum precision. Any of these forms may be followed by the letter w if the given time is local or “wall clock” time, s if the given time is standard time without any adjustment for daylight saving, or u (or g or z) if the given time is universal time; in the absence of an indicator, local (wall clock) time is assumed. These forms ignore leap seconds; for example, if a leap second occurs at 00:59:60 local time, stands for 3601 seconds after local midnight instead of the usual 3600 seconds. The intent is that a rule line describes the instants when a clock/calendar set to the type of time specified in the AT field would show the specified date and time of day.
zic
does not distinguish a 10:30 standard
time plus an 0:30 SAVE from a 10:00 standard time plus a
1:00 SAVE.A zone line has the form
Zone NAME STDOFF RULES/SAVE FORMAT [UNTIL]
For example:
Zone Asia/Amman 2:00 Jordan EE%sT 2017 Oct 27
1:00
The fields that make up a zone line are:
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 information in the previous line in the file used by the previous line. Continuation lines may contain until information, just as zone lines do, indicating that the next line is a further continuation.
If a zone changes at the same instant that a rule would otherwise take effect in the earlier zone or continuation line, the rule is ignored. A zone or continuation line with a named rule set starts with standard time by default: that is, any of timestamps preceding earliest rule use the rule in effect after first transition into standard time. In a single zone it is an error if two rules take effect at the same instant, or if two zone changes take effect at the same instant.
A link line has the form
Link TARGET LINK-NAME
For example:
Link Europe/Istanbul Asia/Istanbul
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.
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:
Leap YEAR MONTH DAY HH:MM:SS CORR R/S
For example:
Leap 2016 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 UTC or (an abbreviation of) “Rolling” if the leap second time given by the other fields should be interpreted as local (wall clock) time.
zic
input, intended to
illustrate many of its features. In this example, the EU rules are for the
European Union and for its predecessor organization, the European Communities.
# 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 | STDOFF | RULES/SAVE | FORMAT | [UNTIL] |
Zone | Europe/Zurich | 0:34:08 | - | LMT | 1853 Jul 16 |
0:29:45.50 | - | BMT | 1894 Jun | ||
1:00 | Swiss | CE%sT | 1981 | ||
1:00 | EU | CE%sT |
Link | Europe/Zurich | Europe/Vaduz |
In this example, the timezone is named Europe/Zurich but it has an
alias as Europe/Vaduz. This example says that Zurich was 34 minutes and 8
seconds east of UT until 1853-07-16 at 00:00, when the legal offset was
changed to 7°26′22.50″; which this works out to
0:29:45.50; zic
treats this by rounding it to
0:29:46. After 1894-06-01 at 00:00 the UT offset became one hour and Swiss
daylight saving rules (defined with lines beginning with “Rule
Swiss” apply. From 1981 to the present, EU daylight saving rules have
From 1981 to the present, EU daylight saving rules have
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 time zone abbreviation has been CET for standard time and CEST for daylight saving time.
If, for a particular timezone, 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
local (wall clock) time. To get separate transitions use multiple zone
continuation lines specifying transition instants using universal time.
July 2, 2019 | NetBSD 9.4 |