Go to main content

man pages section 8: System Administration Commands

Exit Print View

Updated: Wednesday, July 27, 2022



zic - time zone compiler


zic [--version] [-s] [-v] [-d directory | -l localtime]
     [-p posixrules] [-y yearistype] [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.

Input lines are made up of fields. Fields are separated by any number of white space characters. Leading and trailing white space on input lines is ignored. A pound sign (#) indicates a comment that extends to the end of the line. White space characters and pound signs can be enclosed within double quotes (" ") if they are 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, or link lines.


A rule line has the form:

For example:


The fields that make up a rule line are:

Rule   USA   1969  1973   -  Apr lastSun 2:00  1:00   D

Gives the (arbitrary) name of the set of rules this rule is part of.


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.


Gives the final year in which the rule applies. In addition to minimum and maximum (as above), the word only (or an abbreviation) can be used to repeat the value of the FROM field.


Gives the type of year in which the rule applies. If TYPE is:


The rule applies in all years between FROM and TO, inclusive.


The rule applies in U.S. Presidential election years.


The rule applies in years other than U.S. Presidential election years.


The rule applies to even-numbered years.


The rule applies to odd-numbered years.

If TYPE is something else, then zic will attempt to execute the command

yearistype year type

to check the type of a year: an exit status of 0 means that the year is of the given type; an exit status of 1 means that the year is not of the given type. The yearistype command is not currently provided in the Solaris environment.


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


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


the fifth day of the month


The last Sunday in the month


The last Monday in the month


First Sunday on or after the eighth


Last Sunday on or before the 25th

Names of days of the week can be abbreviated or spelled out in full. Note: There cannot be spaces within the ON field.


Gives the time of day at which the rule takes effect. Recognized forms include:


Time in hours


Time in hours and minutes


24-hour format time (for times after noon)


Time in hours, minutes, and seconds, 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 can 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.


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 (without the w and s suffixes).


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.


A zone line has the form:

Zone  NAME                 GMTOFF  RULES/SAVE   FORMAT  [UNTIL]

For example:

Zone Australia/SouthWest   9:30        -         CST    1992 Mar 15 12:00
                           8:30      Aus         CST                  

The fields that make up a zone line are:


The name of the time zone. This is the name used in creating the time conversion information file for the zone.


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 to subtract time from UTC.


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.


The format for time zone abbreviations in this time zone. The pair of characters %s is used to show where the “variable part” of the time zone abbreviation goes. Alternately, a slash (/) separates standard and daylight abbreviations.


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. The time of day has the same format as the AT field of rule lines. 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 line has the same form as a zone line except that the string “Zone” and the name are omitted. The continuation line places information starting at the time specified as the UNTIL field in the previous line in the file used by the previous line. Continuation lines can contain an UNTIL field, just as zone lines do, indicating that the next line is a further continuation.


A link line has the form:


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 can appear in any order in the input.



Outputs version information and exits.

–d directory

Creates time conversion information files in the directory directory rather than in the standard directory /usr/share/lib/zoneinfo.

The –d and –l options are mutually exclusive.

–l localtime

Uses the given time zone as local time localtime. zic acts as if the file contained a link line of the form:

Link localtime localtime

On Oracle Solaris, this option also sets the timezone/localtime property on the smf(7) service svc:/system/timezone:default and refreshes the service. For more information, see tzreload(8).

The –d and –l options are mutually exclusive.

–p posixrules

Uses the rules of the given time zone posixrules when handling POSIX-format time zone environment variables. zic acts as if the input contained a link line of the form:

Link	posixrules posixrules

This option is not used by ctime(3C) and mktime(3C) in the Solaris environment.


Limits time values stored in output files to values that are the same whether they are taken to be signed or unsigned. You can use this option to generate SVVS-compatible files.

This option is obsolete and may be removed in a future release.


Complains if a year that appears in a data file is outside the range of years representable by system time values (0:00:00 a.m. UTC, January 1, 1970, to 3:14:07 a.m. UTC, January 19, 2038). This option also complains if a time of 24:00 (which cannot be handled by pre-1998 versions of zic) appears in the input.

–y yearistype

Uses the given command yearistype rather than yearistype when checking year types (see Rules under DESCRIPTION).



A file containing input lines that specify the time conversion information files to be created. If a filename is '', the standard input is read.



Symbolic link to system local time zone, created by zic –l.


Standard directory used for created files


Directory containing source files


See attributes(7) for descriptions of the following attributes:

Interface Stability

* The –s option is obsolete.

See Also

time(1), ctime(3C), mktime(3C), attributes(7), tzreload(8), zdump(8)


For areas with more than two types of local time, you might 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.

If the current timezone file is modified and compiled using the “zic” command, the changes will only be reflected in any new processes that are started after the change, unless tzreload(8) is run to signal existing processes to reload their time zone data.