mirror of
https://git.FreeBSD.org/src.git
synced 2024-10-18 02:19:39 +00:00
145 lines
7.2 KiB
Plaintext
145 lines
7.2 KiB
Plaintext
zdump(8) System Manager's Manual zdump(8)
|
|
|
|
NAME
|
|
zdump - timezone dumper
|
|
|
|
SYNOPSIS
|
|
zdump [ option ... ] [ timezone ... ]
|
|
|
|
DESCRIPTION
|
|
The zdump program prints the current time in each timezone named on the
|
|
command line.
|
|
|
|
OPTIONS
|
|
--version
|
|
Output version information and exit.
|
|
|
|
--help Output short usage message and exit.
|
|
|
|
-i Output a description of time intervals. For each timezone on
|
|
the command line, output an interval-format description of the
|
|
timezone. See "INTERVAL FORMAT" below.
|
|
|
|
-v Output a verbose description of time intervals. For each
|
|
timezone on the command line, print the times at the two extreme
|
|
time values, the times (if present) at and just beyond the
|
|
boundaries of years that localtime(3) and gmtime(3) can
|
|
represent, and the times both one second before and exactly at
|
|
each detected time discontinuity. Each line is followed by
|
|
isdst=D where D is positive, zero, or negative depending on
|
|
whether the given time is daylight saving time, standard time,
|
|
or an unknown time type, respectively. Each line is also
|
|
followed by gmtoff=N if the given local time is known to be N
|
|
seconds east of Greenwich.
|
|
|
|
-V Like -v, except omit output concerning extreme time and year
|
|
values. This generates output that is easier to compare to that
|
|
of implementations with different time representations.
|
|
|
|
-c [loyear,]hiyear
|
|
Cut off interval output at the given year(s). Cutoff times are
|
|
computed using the proleptic Gregorian calendar with year 0 and
|
|
with Universal Time (UT) ignoring leap seconds. Cutoffs are at
|
|
the start of each year, where the lower-bound timestamp is
|
|
inclusive and the upper is exclusive; for example, -c 1970,2070
|
|
selects transitions on or after 1970-01-01 00:00:00 UTC and
|
|
before 2070-01-01 00:00:00 UTC. The default cutoff is
|
|
-500,2500.
|
|
|
|
-t [lotime,]hitime
|
|
Cut off interval output at the given time(s), given in decimal
|
|
seconds since 1970-01-01 00:00:00 Coordinated Universal Time
|
|
(UTC). The timezone determines whether the count includes leap
|
|
seconds. As with -c, the cutoff's lower bound is inclusive and
|
|
its upper bound is exclusive.
|
|
|
|
INTERVAL FORMAT
|
|
The interval format is a compact text representation that is intended
|
|
to be both human- and machine-readable. It consists of an empty line,
|
|
then a line "TZ=string" where string is a double-quoted string giving
|
|
the timezone, a second line "- - interval" describing the time interval
|
|
before the first transition if any, and zero or more following lines
|
|
"date time interval", one line for each transition time and following
|
|
interval. Fields are separated by single tabs.
|
|
|
|
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.)
|
|
|
|
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, 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.
|
|
|
|
Here are excerpts from another example:
|
|
|
|
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
|
|
|
|
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.
|
|
|
|
LIMITATIONS
|
|
Time discontinuities are found by sampling the results returned by
|
|
localtime(3) at twelve-hour intervals. This works in all real-world
|
|
cases; one can construct artificial time zones for which this fails.
|
|
|
|
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.
|
|
|
|
SEE ALSO
|
|
tzfile(5), zic(8)
|
|
|
|
Time Zone Database zdump(8)
|