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zic - time zone compiler
zic [ -v ] [ -d directory ] [ -l localtime ] [ -p
posixrules ] [ -L leapsecondfilename ] [ -s ] [ -y command
] [ filename ... ]
Zic reads text from the file(s) named on the command line
and creates the time conversion information files speci-
fied in this input. If a filename is -, the standard
input is read.
These options are available:
Create time conversion information files in the
named directory rather than in the standard direc-
tory named below.
Use the given time zone as local time. Zic will
act as if the input contained a link line of the
Link timezone localtime
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
Link timezone posixrules
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.
-v Complain if a year that appears in a data file is
outside the range of years representable by time(3)
-s Limit time values stored in output files to values
that are the same whether they're taken to be
signed or unsigned. You can use this option to
generate SVVS-compatible files.
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 white space characters.
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.
A rule line has the form
Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
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 abbrevia-
tion) means the maximum year representable as an
integer. Rules can describe times that are not
representable as time values, with the unrepre-
sentable 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 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 some-
thing 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
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
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
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 [UNTIL]
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 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
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.
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 abbrevia-
tion goes. Alternately, a slash (/) separates stan-
dard 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 speci-
fied, 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 columns.
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 con-
tinuation line will place information starting at
the time specified as the UNTIL field in the previ-
ous line in the file used by the previous line.
Continuation lines may contain an UNTIL field, just
as zone lines do, indicating that the next line is a
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 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
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 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.
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 earli-
est transition time recorded in the compiled file is cor-
/usr/share/zoneinfo standard directory used for cre-
ctime(3), tzfile(5), zdump(8)
Source: OpenBSD 2.6 man pages. Copyright: Portions are copyrighted by BERKELEY
SOFTWARE DESIGN, INC., The Regents of the University of California, Massachusetts
Institute of Technology, Free Software Foundation, FreeBSD Inc., and others.
(Corrections, notes, and links courtesy of RocketAware.com)
FreeBSD Sources for zic(8)
OpenBSD sources for zic(8)
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