1zdump(8) System Manager's Manual zdump(8) 2 3NAME 4 zdump - timezone dumper 5 6SYNOPSIS 7 zdump [ option ... ] [ timezone ... ] 8 9DESCRIPTION 10 The zdump program prints the current time in each timezone named on the 11 command line. 12 13OPTIONS 14 --version 15 Output version information and exit. 16 17 --help Output short usage message and exit. 18 19 -i Output a description of time intervals. For each timezone on 20 the command line, output an interval-format description of the 21 timezone. See "INTERVAL FORMAT" below. 22 23 -v Output a verbose description of time intervals. For each 24 timezone on the command line, print the times at the two extreme 25 time values, the times (if present) at and just beyond the 26 boundaries of years that localtime(3) and gmtime(3) can 27 represent, and the times both one second before and exactly at 28 each detected time discontinuity. Each line is followed by 29 isdst=D where D is positive, zero, or negative depending on 30 whether the given time is daylight saving time, standard time, 31 or an unknown time type, respectively. Each line is also 32 followed by gmtoff=N if the given local time is known to be N 33 seconds east of Greenwich. 34 35 -V Like -v, except omit output concerning extreme time and year 36 values. This generates output that is easier to compare to that 37 of implementations with different time representations. 38 39 -c [loyear,]hiyear 40 Cut off interval output at the given year(s). Cutoff times are 41 computed using the proleptic Gregorian calendar with year 0 and 42 with Universal Time (UT) ignoring leap seconds. Cutoffs are at 43 the start of each year, where the lower-bound timestamp is 44 inclusive and the upper is exclusive; for example, -c 1970,2070 45 selects transitions on or after 1970-01-01 00:00:00 UTC and 46 before 2070-01-01 00:00:00 UTC. The default cutoff is 47 -500,2500. 48 49 -t [lotime,]hitime 50 Cut off interval output at the given time(s), given in decimal 51 seconds since 1970-01-01 00:00:00 Coordinated Universal Time 52 (UTC). The timezone determines whether the count includes leap 53 seconds. As with -c, the cutoff's lower bound is inclusive and 54 its upper bound is exclusive. 55 56INTERVAL FORMAT 57 The interval format is a compact text representation that is intended 58 to be both human- and machine-readable. It consists of an empty line, 59 then a line "TZ=string" where string is a double-quoted string giving 60 the timezone, a second line "- - interval" describing the time interval 61 before the first transition if any, and zero or more following lines 62 "date time interval", one line for each transition time and following 63 interval. Fields are separated by single tabs. 64 65 Dates are in yyyy-mm-dd format and times are in 24-hour hh:mm:ss format 66 where hh<24. Times are in local time immediately after the transition. 67 A time interval description consists of a UT offset in signed +-hhmmss 68 format, a time zone abbreviation, and an isdst flag. An abbreviation 69 that equals the UT offset is omitted; other abbreviations are double- 70 quoted strings unless they consist of one or more alphabetic 71 characters. An isdst flag is omitted for standard time, and otherwise 72 is a decimal integer that is unsigned and positive (typically 1) for 73 daylight saving time and negative for unknown. 74 75 In times and in UT offsets with absolute value less than 100 hours, the 76 seconds are omitted if they are zero, and the minutes are also omitted 77 if they are also zero. Positive UT offsets are east of Greenwich. The 78 UT offset -00 denotes a UT placeholder in areas where the actual offset 79 is unspecified; by convention, this occurs when the UT offset is zero 80 and the time zone abbreviation begins with "-" or is "zzz". 81 82 In double-quoted strings, escape sequences represent unusual 83 characters. The escape sequences are \s for space, and \", \\, \f, \n, 84 \r, \t, and \v with their usual meaning in the C programming language. 85 E.g., the double-quoted string ""CET\s\"\\"" represents the character 86 sequence "CET "\". 87 88 Here is an example of the output, with the leading empty line omitted. 89 (This example is shown with tab stops set far enough apart so that the 90 tabbed columns line up.) 91 92 TZ="Pacific/Honolulu" 93 - - -103126 LMT 94 1896-01-13 12:01:26 -1030 HST 95 1933-04-30 03 -0930 HDT 1 96 1933-05-21 11 -1030 HST 97 1942-02-09 03 -0930 HWT 1 98 1945-08-14 13:30 -0930 HPT 1 99 1945-09-30 01 -1030 HST 100 1947-06-08 02:30 -10 HST 101 102 Here, local time begins 10 hours, 31 minutes and 26 seconds west of UT, 103 and is a standard time abbreviated LMT. Immediately after the first 104 transition, the date is 1896-01-13 and the time is 12:01:26, and the 105 following time interval is 10.5 hours west of UT, a standard time 106 abbreviated HST. Immediately after the second transition, the date is 107 1933-04-30 and the time is 03:00:00 and the following time interval is 108 9.5 hours west of UT, is abbreviated HDT, and is daylight saving time. 109 Immediately after the last transition the date is 1947-06-08 and the 110 time is 02:30:00, and the following time interval is 10 hours west of 111 UT, a standard time abbreviated HST. 112 113 Here are excerpts from another example: 114 115 TZ="Europe/Astrakhan" 116 - - +031212 LMT 117 1924-04-30 23:47:48 +03 118 1930-06-21 01 +04 119 1981-04-01 01 +05 1 120 1981-09-30 23 +04 121 ... 122 2014-10-26 01 +03 123 2016-03-27 03 +04 124 125 This time zone is east of UT, so its UT offsets are positive. Also, 126 many of its time zone abbreviations are omitted since they duplicate 127 the text of the UT offset. 128 129LIMITATIONS 130 Time discontinuities are found by sampling the results returned by 131 localtime(3) at twelve-hour intervals. This works in all real-world 132 cases; one can construct artificial time zones for which this fails. 133 134 In the -v and -V output, "UT" denotes the value returned by gmtime(3), 135 which uses UTC for modern timestamps and some other UT flavor for 136 timestamps that predate the introduction of UTC. No attempt is 137 currently made to have the output use "UTC" for newer and "UT" for 138 older timestamps, partly because the exact date of the introduction of 139 UTC is problematic. 140 141SEE ALSO 142 tzfile(5), zic(8) 143 144Time Zone Database zdump(8) 145