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NAME | SYNOPSIS | DESCRIPTION | FILES | NOTES | SEE ALSO | COLOPHON |
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ZIC(8) Linux System Administration ZIC(8)
zic - timezone compiler
zic [-v] [-d directory] [-l localtime] [-p posixrules]
[-L leapsecondfilename] [-s] [-y command] [filename...]
The 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.
These options are available:
-d directory
Create time conversion information files in the named
directory rather than in the standard directory named below.
-l timezone
Use the given timezone 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 timezone's rules when handling POSIX-format
timezone environment variables. zic will act as if the input
contained a link line of the form
Link timezone posixrules
-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.
-v Complain if a year that appears in a data file is outside the
range of years representable by time(2) values.
-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.
-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 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. Nonblank 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
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 timezone 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 UTCOFF RULES/SAVE FORMAT [UNTIL]
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 timezone. This is the name used in creating
the time conversion information file for the zone.
UTCOFF
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 timezone or,
alternately, an amount of time to add to local standard time.
If this field is -, then standard time always applies in the
timezone.
FORMAT
The format for timezone abbreviations in this timezone. The
pair of characters %s is used to show where the "variable part"
of the timezone abbreviation goes. Alternately, a slash (/)
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 timezone 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 continuation line will place information
starting at the time specified as the UNTIL field in the
previous 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 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.
/usr/local/etc/zoneinfo
Standard directory used for created files.
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.
tzfile(5), zdump(8)
This page is part of release 4.15 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
2010-02-25 ZIC(8)
Pages that refer to this page: tzfile(5), tzselect(8), zdump(8)
Copyright and license for this manual page
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