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 specified in this input. If a filename is -, the standard input is read.
These options are available:
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:
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.
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.
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 zone.
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 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
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
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.
/usr/local/etc/zoneinfo standard directory used for created files
tzfile(5) , zdump(8)
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