zic — timezone 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 specified in this
input. If a filename
is −, the
standard input is read.
These options are available:
−d
directoryCreate time conversion information files in the named directory rather than in the standard directory named below.
−l
timezoneUse the given timezone as local time. Zic will act as if the input contained a link line of the form
Link timezone localtime
−p
timezoneUse 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
leapsecondfilenameRead leap second information from the file with the given name. If this option is not used, no leap second information appears in output files.
−vComplain if a year that appears in a data file is outside the range of years representable by time(2) values.
−sLimit 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
commandUse 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:
NAMEGives the (arbitrary) name of the set of rules this rule is part of.
FROMGives 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.
TOGives 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.
TYPEGives 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.
INNames the month in which the rule takes effect. Month names may be abbreviated.
ONGives 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.
ATGives 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.
SAVEGives 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).
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:
NAMEThe name of the timezone. This is the name used in creating the time conversion information file for the zone.
UTCOFFThe 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.
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.
FORMATThe 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.
UNTILThe 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.
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.
This page is part of release 4.07 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/.
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