| NAME | SYNOPSIS | DESCRIPTION | FILES | NOTES | SEE ALSO | COLOPHON | The Linux Programming Interface |
ZIC(8) Linux System Administration ZIC(8)
zic - timezone compiler
zic [ -v ] [ -d directory ] [ -l localtime ] [ -p posixrules ] [ -L leapsec-
ondfilename ] [ -s ] [ -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 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 3.32 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
2010-02-25 ZIC(8)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface