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 time zone 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 time zone's rules when handling POSIX-format time zone 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. 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 For example: Rule USA 1969 1973 - Apr lastSun 2:00 1:00 DThe fields that make up a rule line are:
"\w'LETTER/S'u" 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. The word minimum (or an abbreviation) means the minimum year with a representable time value. The word maximum (or an abbreviation) means the maximum year with a representable 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 uspres , the rule applies in U.S. Presidential election years; if TYPE is nonpres , the rule applies in years other than U.S. Presidential election years. 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 25thNames 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 secondsAny of these forms may be followed by the letter w if the given time is local .q "wall clock" time or s if the given time is local .q standard time; in the absence of w or s , 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 .q "variable part" (for example, the .q S or .q D in .q EST or .q 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] For example: Zone Australia/South-west 9:30 Aus CST 1987 Mar 15 2:00The fields that make up a zone line are:
"\w'GMTOFF'u" NAME The name of the time zone. This is the name used in creating the time conversion information file for the zone.
GMTOFF The amount of time to add to GMT 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 GMT.
RULES/SAVE 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.
FORMAT The format for time zone abbreviations in this time zone. The pair of characters %s is used to show where the .q "variable part" of the time zone abbreviation goes.
UNTIL The time at which the GMT 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 GMT offset and rule change until the time specified.
The next line must be a .q continuation line; this has the same form as a zone line except that the string .q 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 US/Eastern EST5EDTThe 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 + SThe YEAR , MONTH , DAY , and HH:MM:SS fields tell when the leap second happened. The CORR field should be .q + if a second was added or .q - if a second was skipped. The R/S field should be (an abbreviation of) .q Stationary if the leap second time given by the other fields should be interpreted as GMT or (an abbreviation of) .q Rolling if the leap second time given by the other fields should be interpreted as local wall clock time.