ZIC(8) OpenBSD System Manager's Manual ZIC(8)NAMEzic - time zone compiler
SYNOPSISzic [-v] [-d directory] [-L leapsecondfilename] [-l timezone]
[-p timezone] [-y command] [filename ...]
DESCRIPTIONzic 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 ``-'', the standard input is read.
These options are available:
-d directory Create time conversion information files in the named
directory rather than in the standard directory named
below.
-L leapsecondfilename
Read leap second information from the file with the given
name. If this option is not used, no leap second
information appears in output files.
-l timezone Use the given time zone as local time. zic will act as if
the input contained a link line of the form
Link timezone localtime
-p timezone Use the given time zone's rules when handling POSIX-format
time zone environment variables. zic will act as if the
input contained a link line of the form
Link timezone posixrules
-v Complain if a year that appears in a data file is outside
the range of years representable by time(3) values. Also
complain if a time of 24:00 (which cannot be handled by
pre-1998 versions of zic) appears in the input.
-y command Use the given command rather than yearistype when checking
year types (see below).
Input lines are made up of fields. Fields are separated from one another
by any number of whitespace characters. Leading and trailing whitespace
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:
Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
For example:
Rule US 1967 1973 - Apr lastSun 2:00 1:00 D
The fields that make up a rule line are:
NAME Gives the (arbitrary) name of the set of rules this rule is
part of.
FROM Gives the first year in which the rule applies. Any integer
year can be supplied; the Gregorian calendar is assumed. The
word minimum (or an abbreviation) means the minimum year
representable as an integer. The word maximum (or an
abbreviation) means the maximum year representable as an
integer. Rules can describe times that are not representable
as time values, with the unrepresentable times ignored; this
allows rules to be portable among hosts with differing time
value types.
TO Gives the final year in which the rule applies. In addition to
minimum and maximum (as above), the word only (or an
abbreviation) may be used to repeat the value of the FROM
field.
TYPE Gives the type of year in which the rule applies. If TYPE is
``-'' then the rule applies in all years between FROM and TO
inclusive. If TYPE is something else, then zic executes the
command
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.
IN Names the month in which the rule takes effect. Month names
may be abbreviated.
ON Gives the day on which the rule takes effect. Recognized forms
include:
5 the fifth of the month
lastSun the last Sunday in the month
lastMon the last Monday in the month
Sun>=8 first Sunday on or after the eighth
Sun<=25 last Sunday on or before the 25th
Names of days of the week may be abbreviated or spelled out in
full. Note that there must be no spaces within the ON field.
AT Gives the time of day at which the rule takes effect.
Recognized forms include:
2 time in hours
2:00 time in hours and minutes
15:00 24-hour format time (for times after noon)
1:28:14 time in hours, minutes, and seconds
- equivalent to 0
where hour 0 is midnight at the start of the day, and hour 24
is midnight at the end of the day. Any of these forms may be
followed by the letter w if the given time is local ``wall
clock'' time, s if the given time is local ``standard'' time,
or u (or g or z) if the given time is universal time; in the
absence of an indicator, wall clock time is assumed.
SAVE Gives the amount of time to be added to local standard time
when the rule is in effect. This field has the same format as
the AT field (although, of course, the w and s suffixes are not
used).
LETTER/S Gives the ``variable part'' (for example, the ``S'' or ``D'' in
``EST'' or ``EDT'') of time zone abbreviations to be used when
this rule is in effect. If this field is ``-'' the variable
part is null.
A zone line has the form:
Zone NAME GMTOFF RULES/SAVE FORMAT [UNTILYEAR [MONTH [DAY [TIME]]]]
For example:
Zone Australia/Adelaide 9:30 Aus CST 1971 Oct 31 2:00
The fields that make up a zone line are:
NAME The name of the time zone. This is the name used in creating the
time conversion information file for the zone.
GMTOFF The amount of time to add to UTC to get standard time in this
zone. This field has the same format as the AT and SAVE fields
of rule lines; begin the field with a minus sign if time must be
subtracted from UTC.
RULES/SAVE
The name of the rule(s) that apply in the time zone or,
alternately, an amount of time to add to local standard time. If
this field is ``-'' then standard time always applies in the time
zone.
FORMAT The format for time zone abbreviations in this time zone. The
pair of characters %s is used to show where the ``variable part''
of the time zone abbreviation goes. Alternately, a slash (/)
separates standard and daylight abbreviations.
UNTILYEAR [MONTH [DAY [TIME]]]
The time at which the UTC offset or the rule(s) change for a
location. It is specified as a year, a month, a day, and a time
of day. If this is specified, the time zone information is
generated from the given UTC offset and rule change until the
time specified. The month, day, and time of day have the same
format as the IN, ON, and AT fields of a rule; trailing fields
can be omitted, and default to the earliest possible value for
the missing fields.
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.
A link line has the form:
Link LINK-FROM LINK-TO
For example:
Link Europe/Istanbul Asia/Istanbul
The LINK-FROM field should appear as the NAME field in some zone line;
the LINK-TO field is used as an alternate name for that zone.
Except for continuation lines, lines may appear in any order in the
input.
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 1974 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.
EXTENDED EXAMPLE
Here is an extended example of zic input, intended to illustrate many of
its features.
# Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
Rule Swiss 1940 only - Nov 2 0:00 1:00 S
Rule Swiss 1940 only - Dec 31 0:00 0 -
Rule Swiss 1941 1942 - May Sun>=1 2:00 1:00 S
Rule Swiss 1941 1942 - Oct Sun>=1 0:00 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 FORMAT UNTIL
Zone Europe/Zurich 0:34:08 - LMT 1848 Sep 12
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. Zurich was 34 minutes and 8 seconds west of GMT until 1848-
09-12 at 00:00, when the offset changed to 29 minutes and 44 seconds.
After 1894-06-01 at 00:00 Swiss daylight saving rules (defined with lines
beginning with "Rule Swiss") apply, and the GMT 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 1940, daylight saving time applied from November 2 at 00:00 to
December 31 at 00:00. In 1941 and 1942, daylight saving time applied
from the first Sunday in May at 02:00 to the first Sunday in October at
00:00. 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 timezone has been CET for standard time and CEST for
daylight saving time.
FILES
/etc/localtime link to local time zone
/usr/share/zoneinfo standard directory used for created files
SEE ALSOctime(3), tzfile(5), zdump(8)CAVEATS
For areas with more than two types of local time, you may need to use
local standard time in the AT field of the earliest transition time's
rule to ensure that the earliest transition time recorded in the compiled
file is correct.
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 UTC offset, zic produces a single transition to daylight
saving at the new UTC offset (without any change in wall clock time). To
get separate transitions use multiple zone continuation lines specifying
transition instants using universal time.
OpenBSD 4.9 August 23, 2010 OpenBSD 4.9
