|ZDUMP(8)||System Manager's Manual||ZDUMP(8)|
Dates are in yyyy-mm-dd format and times are in 24-hour hh:mm:ss format where hh<24. Times are in local time immediately after the transition. A time interval description consists of a UT offset in signed ±hhmmss format, a time zone abbreviation, and an isdst flag. An abbreviation that equals the UT offset is omitted; other abbreviations are double-quoted strings unless they consist of one or more alphabetic characters. An isdst flag is omitted for standard time, and otherwise is a decimal integer that is unsigned and positive (typically 1) for daylight saving time and negative for unknown.
In times and in UT offsets with absolute value less than 100 hours, the seconds are omitted if they are zero, and the minutes are also omitted if they are also zero. Positive UT offsets are east of Greenwich. The UT offset -00 denotes a UT placeholder in areas where the actual offset is unspecified; by convention, this occurs when the UT offset is zero and the time zone abbreviation begins with “-” or is “zzz”.
In double-quoted strings, escape sequences represent unusual characters. The escape sequences are \s for space, and \", \\, \f, \n, \r, \t, and \v with their usual meaning in the C programming language. E.g., the double-quoted string “"CET\s\"\\"” represents the character sequence “CET "\”.
Here is an example of the output, with the leading empty line omitted. (This example is shown with tab stops set far enough apart so that the tabbed columns line up.)
Here, local time begins 10 hours, 31 minutes and 26 seconds west of UT, and is a standard time abbreviated LMT. Immediately after the first transition, the date is 1896-01-13 and the time is 12:01:26, and the following time interval is 10.5 hours west of UT, a standard time abbreviated HST. Immediately after the second transition, the date is 1933-04-30 and the time is 03:00:00 and the following time interval is 9.5 hours west of UT, is abbreviated HDT, and is daylight saving time. Immediately after the last transition the date is 1947-06-08 and the time is 02:30:00, and the following time interval is 10 hours west of UT, a standard time abbreviated HST.
TZ="Pacific/Honolulu" - - -103126 LMT 1896-01-13 12:01:26 -1030 HST 1933-04-30 03 -0930 HDT 1 1933-05-21 11 -1030 HST 1942-02-09 03 -0930 HWT 1 1945-08-14 13:30 -0930 HPT 1 1945-09-30 01 -1030 HST 1947-06-08 02:30 -10 HST
Here are excerpts from another example:
This time zone is east of UT, so its UT offsets are positive. Also, many of its time zone abbreviations are omitted since they duplicate the text of the UT offset.
TZ="Europe/Astrakhan" - - +031212 LMT 1924-04-30 23:47:48 +03 1930-06-21 01 +04 1981-04-01 01 +05 1 1981-09-30 23 +04 ... 2014-10-26 01 +03 2016-03-27 03 +04
In the -v and -V output, “UT” denotes the value returned by gmtime(3), which uses UTC for modern timestamps and some other UT flavor for timestamps that predate the introduction of UTC. No attempt is currently made to have the output use “UTC” for newer and “UT” for older timestamps, partly because the exact date of the introduction of UTC is problematic.