Output version information and exit.

Output short usage message and exit.

Output backward-compatibility data as specified by bloat. If bloat is fat, generate additional data entries that work around potential bugs or incompatibilities in older software, such as software that mishandles the 64-bit generated data. If bloat is slim, keep the output files small; this can help check for the bugs and incompatibilities. Although the default is currently fat, this is intended to change in future zic versions, as software that mishandles the 64-bit data typically mishandles timestamps after the year 2038 anyway. Also see the −r option for another way to shrink output size.

Create time conversion information files in the named directory rather than in the standard directory named below.

Use timezone as local time. zic will act as if the input contained a link line of the form

Link    timezone        localtime

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.

Use timezone's rules when handling nonstandard TZ strings like "EET-2EEST" that lack transition rules. zic will act as if the input contained a link line of the form

This feature is obsolete and poorly supported. Among other things it should not be used for timestamps after the year 2037, and it should not be combined with −b slim if timezone's transitions are at standard time or Universal Time (UT) instead of local time.

Reduce the size of output files by limiting their applicability to timestamps in the range from lo (inclusive) to hi (exclusive), where lo and hi are possibly-signed decimal counts of seconds since the Epoch (1970-01-01 00:00:00 UTC). Omitted counts default to extreme values. For example, “zic \*-r @0” omits data intended for negative timestamps (i.e., before the Epoch), and “zic \*-r @0/@2147483648” outputs data intended only for nonnegative timestamps that fit into 31-bit signed integers. On platforms with GNU date, “zic \-r @$(date +%s)” omits data intended for past timestamps. Also see the −b slim option for another way to shrink output size.

When creating local time information, put the configuration link in the named file rather than in the standard location.

Be more verbose, and complain about the following situations:

Gives the name of the rule set that contains this line. The name must start with a character that is neither an ASCII digit nor “\*-” nor “+”. To allow for future extensions, an unquoted name should not contain characters from the set “!$%&'()*,/:;<=>?@[\e]\(ha\`{|}\(ti”.

Gives the first year in which the rule applies. Any signed integer year can be supplied; the proleptic Gregorian calendar is assumed, with year 0 preceding year 1. The word minimum (or an abbreviation) means the indefinite past. The word maximum (or an abbreviation) means the indefinite future. 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.

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.

should be “\*-” and is present for compatibility with older versions of zic in which it could contain year types.

Names the month in which the rule takes effect. Month names may be abbreviated.

Gives the day on which the rule takes effect. Recognized forms include:

A weekday name (e.g., Sunday) or a weekday name preceded by “last” (e.g., lastSunday) may be abbreviated or spelled out in full. There must be no white space characters within the ON field. The “<=” and “>=” constructs can result in a day in the neighboring month; for example, the IN-ON combination “Oct Sun>=31” stands for the first Sunday on or after October 31, even if that Sunday occurs in November.

Gives the time of day at which the rule takes effect, relative to 00:00, the start of a calendar day. Recognized forms include:

Although zic rounds times to the nearest integer second (breaking ties to the even integer), the fractions may be useful to other applications requiring greater precision. The source format does not specify any maximum precision. Any of these forms may be followed by the letter w if the given time is local or “wall clock” time, s if the given time is standard time without any adjustment for daylight saving, or u (or g or z) if the given time is universal time; in the absence of an indicator, local (wall clock) time is assumed. These forms ignore leap seconds; for example, if a leap second occurs at 00:59:60 local time, “1:00” stands for 3601 seconds after local midnight instead of the usual 3600 seconds. The intent is that a rule line describes the instants when a clock/calendar set to the type of time specified in the AT field would show the specified date and time of day.

Gives the amount of time to be added to local standard time when the rule is in effect, and whether the resulting time is standard or daylight saving. This field has the same format as the AT field except with a different set of suffix letters: s for standard time and d for daylight saving time. The suffix letter is typically omitted, and defaults to s if the offset is zero and to d otherwise. Negative offsets are allowed; in Ireland, for example, daylight saving time is observed in winter and has a negative offset relative to Irish Standard Time. The offset is merely added to standard time; for example, zic does not distinguish a 10:30 standard time plus an 0:30 SAVE from a 10:00 standard time plus a 1:00 SAVE.

Gives the “variable part” (for example, the “S” or “D” in “EST” or “EDT”) of time zone abbreviations to be used when this rule is in effect. If this field is “\*-”, the variable part is null.

The name of the timezone. This is the name used in creating the time conversion information file for the timezone. It should not contain a file name component “.\&” or “..”; a file name component is a maximal substring that does not contain “/”.

The amount of time to add to UT to get standard time, without any adjustment for daylight saving. 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 UT.

The name of the rules that apply in the timezone or, alternatively, a field in the same format as a rule-line SAVE column, giving of the amount of time to be added to local standard time effect, and whether the resulting time is standard or daylight saving. If this field is - then standard time always applies. When an amount of time is given, only the sum of standard time and this amount matters.

The format for time zone abbreviations. The pair of characters %s is used to show where the “variable part” of the time zone abbreviation goes. Alternatively, a format can use the pair of characters %z to stand for the UT offset in the form ±hh, ±hhmm, or ±hhmmss, using the shortest form that does not lose information, where hh, mm, and ss are the hours, minutes, and seconds east (+) or west (−) of UT. Alternatively, a slash (/) separates standard and daylight abbreviations. To conform to POSIX, a time zone abbreviation should contain only alphanumeric ASCII characters, “+” and “\*-”.

The time at which the UT offset or the rule(s) change for a location. It takes the form of one to four fields YEAR [MONTH [DAY [TIME]]]. If this is specified, the time zone information is generated from the given UT offset and rule change until the time specified, which is interpreted using the rules in effect just before the transition. The month, day, and time of day have the same format as the IN, ON, and AT fields of a rule; trailing fields can be omitted, and default to the earliest possible value for the missing fields.

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” information in the previous line in the file used by the previous line. Continuation lines may contain “until” information, just as zone lines do, indicating that the next line is a further continuation.

Default local timezone file.

Default timezone information directory.