zic - time zone compiler
zic [-sv] [-d directory] [-L leapsecondfilename] [-l
[-p timezone] [-y command] [filename ...]
zic 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
Read leap second information from the file
with the given
name. If this option is not used, no leap
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
time zone environment variables. zic will act
as if the
input contained a link line of the form
Link timezone posixrules
-s Limit time values stored in output files to
values that are
the same whether they're taken to be signed or
You can use this option to generate SVVS-compatible files.
-v Complain if a year that appears in a data file
the range of years representable by time(3)
complain if a time of 24:00 (which cannot be
pre-1998 versions of zic) appears in the input.
-y command Use the given command rather than yearistype
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
Any line that is blank (after comment stripping) is ignored.
lines are expected to be of one of three types: rule lines,
and link lines.
A rule line has the form
Rule NAME FROM TO TYPE IN ON AT SAVE
Rule US 1967 1973 - Apr lastSun 2:00 1:00
The fields that make up a rule line are:
NAME Gives the (arbitrary) name of the set of rules
this rule is
FROM Gives the first year in which the rule applies.
year can be supplied; the Gregorian calendar is
word minimum (or an abbreviation) means the minimum year representable
as an integer. The word maximum (or an
means the maximum year representable as an integer. Rules can
describe times that are not representable as time
the unrepresentable times ignored; this allows
rules to be
portable among hosts with differing time value
TO Gives the final year in which the rule applies.
In addition to
minimum and maximum (as above), the word only (or
may be used to repeat the value of the FROM
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
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
IN Names the month in which the rule takes effect.
may be abbreviated.
ON Gives the day on which the rule takes effect.
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
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
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
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 ``-''
part is null.
A zone line has the form
Zone NAME GMTOFF RULES/SAVE FORMAT
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
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
of rule lines; begin the field with a minus sign if
time must be
subtracted from UTC.
The name of the rule(s) that apply in the time zone
an amount of time to add to local standard
time. If this
field is ``-'' then standard time always applies in
FORMAT The format for time zone abbreviations in this time
pair of characters %s is used to show where the
of the time zone abbreviation goes. Alternately, a
separates standard and daylight abbreviations.
UNTIL 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 columns of a rule; trailing
columns can be
omitted, and default to the earliest possible value
for the missing
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 field in
line in the file used by the previous line. Continuation lines
may contain an UNTIL field, just as zone lines do,
that the next line is a further continuation.
A link line has the form
Link LINK-FROM LINK-TO
Link Europe/Istanbul Asia/Istanbul
The LINK-FROM field should appear as the NAME field in some
the LINK-TO field is used as an alternate name for that
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
Leap 1974 Dec 31 23:59:60 + S
The YEAR, MONTH, DAY, and HH:MM:SS fields tell when the leap
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
be interpreted as UTC or (an abbreviation of) ``Rolling'' if
second time given by the other fields should be interpreted
as local wall
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
to ensure that the earliest transition time recorded in the
/etc/localtime link to local time zone
/usr/share/zoneinfo standard directory used for created
ctime(3), tzfile(5), zdump(8)
OpenBSD 3.6 May 23, 1999
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