version 1.14, 2014/10/23 18:45:58 |
version 1.15, 2016/10/07 15:29:42 |
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.\" $NetBSD$ |
.\" $NetBSD$ |
.Dd October 23, 2014 |
.Dd October 6, 2016 |
.Dt ZDUMP 8 |
.Dt ZDUMP 8 |
.Os |
.Os |
.Sh NAME |
.Sh NAME |
Line 26 These options are available: |
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Line 26 These options are available: |
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.Bl -tag -width XXXXXXXXX -compact |
.Bl -tag -width XXXXXXXXX -compact |
.It Fl \-version |
.It Fl \-version |
Output version information and exit. |
Output version information and exit. |
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.It Fl i |
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.Em This option is experimental: its behavior may change in future versions. |
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Output a description of time intervals. |
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For each |
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.Ar zonename |
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on the command line, output an interval-format description of the |
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zone. |
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See |
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.Sx "INTERVAL FORMAT" |
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below. |
.It Fl v |
.It Fl v |
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Output a verbose description of time intervals. |
For each |
For each |
.Ar zonename |
.Ar zonename |
on the command line, |
on the command line, |
Line 37 each detected time discontinuity, |
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Line 48 each detected time discontinuity, |
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the time at one day less than the highest possible time value, |
the time at one day less than the highest possible time value, |
and the time at the highest possible time value. |
and the time at the highest possible time value. |
Each line is followed by |
Each line is followed by |
.Dl isdst= D |
.Em isdst=D |
where |
where |
.Dl D |
.Em D |
is positive, zero, or negative depending on whether |
is positive, zero, or negative depending on whether |
the given time is daylight saving time, standard time, |
the given time is daylight saving time, standard time, |
or an unknown time type, respectively. |
or an unknown time type, respectively. |
Each line is also followed by |
Each line is also followed by |
.Dl gmtoff= N |
.Em gmtoff=N |
if the given local time is known to be |
if the given local time is known to be |
.D N |
.Em N |
seconds east of Greenwich. |
seconds east of Greenwich. |
.It Fl c Ar [loyear,]highyear |
.It Fl c Ar [loyear,]highyear |
Cut off verbose output at the given year(s). |
Cut off interval output at the given year(s). |
Cutoff times are computed using the proleptic Gregorian calendar with year 0 |
Cutoff times are computed using the proleptic Gregorian calendar with year 0 |
and with Universal Time (UT) ignoring leap seconds. |
and with Universal Time (UT) ignoring leap seconds. |
The lower bound is exclusive and the upper is inclusive; for example, a |
The lower bound is exclusive and the upper is inclusive; for example, a |
.Dl loyear |
.Em loyear |
of 1970 excludes a transition occurring at 1970-01-01 00:00:00 UTC but a |
of 1970 excludes a transition occurring at 1970-01-01 00:00:00 UTC but a |
.Dl hiyear |
.Em hiyear |
of 1970 includes the transition. |
of 1970 includes the transition. |
The default cutoff is |
The default cutoff is |
.Dl \*-500,2500 . |
.Em \&-500,2500 . |
.It Fl t Ar [lotime,]hightime |
.It Fl t Ar [lotime,]hightime |
Cut off verbose output at the given time(s), |
Cut off interval output at the given time(s), |
given in decimal seconds since 1970-01-01 00:00:00 |
given in decimal seconds since 1970-01-01 00:00:00 |
Coordinated Universal Time (UTC). |
Coordinated Universal Time (UTC). |
The |
The |
Line 76 except omit the times relative to the ex |
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Line 87 except omit the times relative to the ex |
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This generates output that is easier to compare to that of |
This generates output that is easier to compare to that of |
implementations with different time representations. |
implementations with different time representations. |
.El |
.El |
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.Sh "INTERVAL FORMAT" |
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.Em This format is experimental: it may change in future versions. |
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.Pp |
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The interval format is a compact text representation that is intended |
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to be both human- and machine-readable. |
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It consists of an empty line, then a line |
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.Dq TZ=string |
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where |
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.Dv string |
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is a double-quoted string giving the zone name, a second line |
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.Dq \&- \&- interval |
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describing the time interval before the first transition if any, and |
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zero or more following lines |
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.Dq date time interval |
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one line for each transition time and following interval. |
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Fields are separated by single tabs. |
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.Pp |
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Dates are in |
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.Dv yyyy-mm-dd |
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format and times are in 24-hour |
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.Dv hh:mm:ss |
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format where |
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.Dv hh \*[Lt] 24 . |
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Times are in local time immediately after the transition. |
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A time interval description consists of a UT offset in signed |
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.Dv \&+- hh : mm : ss |
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format, a time zone abbreviation, and an isdst flag. |
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An abbreviation that equals the UT offset is omitted; other abbreviations are |
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double-quoted strings unless they consist of one or more alphabetic |
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characters. |
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An isdst flag is omitted for standard time, and otherwise |
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is a decimal integer that is unsigned and positive (typically 1) for |
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daylight saving time and negative for unknown. |
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.Pp |
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In times and UT offsets, the seconds are omitted if they are zero, and |
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the minutes are also omitted if they are also zero. |
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Positive UT offsets are east of Greenwich. The UT offset \&-00 denotes a UT |
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placeholder in areas where the actual offset is unspecified; by |
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convention, this occurs when the UT offset is zero and the time zone |
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abbreviation begins with |
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.Dq \&- |
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or is |
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.Dq zzz . |
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.Pp |
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In double-quoted strings, escape sequences represent unusual |
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characters. The escape sequences are \es for space, and \e", \e\e, |
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\ef, \en, \er, \et, and \ev with their usual meaning in the C |
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programming language. |
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E.g., the double-quoted string |
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.Sq "CET\es\e"\e\e" |
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represents the character sequence |
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.Sq CET |
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.Pp |
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Here is an example of the output, with the leading empty line omitted. |
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(This example is shown with tab stops set far enough apart so that the |
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tabbed columns line up.) |
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.Bd -literal |
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TZ="Pacific/Honolulu" |
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.Ed |
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.Bl -column "XXXX-XX-XX" "HH:MM:SS" "-HH:MM:SS" "TZT" "X" -compact |
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.It - Ta - Ta -10:31:26 Ta LMT Ta |
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.It 1896-01-13 Ta 12:01:26 Ta -10:30 Ta HST Ta |
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.It 1933-04-30 Ta 03 Ta -09:30 Ta HDT Ta 1 |
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.It 1933-05-21 Ta 11 Ta -10:30 Ta HST Ta |
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.It 1942-02-09 Ta 03 Ta -09:30 Ta HDT Ta 1 |
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.It 1945-09-30 Ta 01 Ta -10:30 Ta HST Ta |
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.It 1947-06-08 Ta 02:30 Ta -10 Ta HST Ta |
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.El |
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.Pp |
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Here, local time begins 10 hours, 31 minutes and 26 seconds west of |
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UT, and is a standard time abbreviated LMT. Immediately after the |
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first transition, the date is 1896-01-13 and the time is 12:01:26, and |
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the following time interval is 10.5 hours west of UT, a standard time |
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abbreviated HST. |
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Immediately after the second transition, the date is |
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1933-04-30 and the time is 03:00:00 and the following time interval is |
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9.5 hours west of UT, is abbreviated HDT, and is daylight saving time. |
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Immediately after the last transition the date is 1947-06-08 and the |
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time is 02:30:00, and the following time interval is 10 hours west of |
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UT, a standard time abbreviated HST. |
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.Pp |
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Here are excerpts from another example: |
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.Bd -literal |
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TZ="Europe/Astrakhan" |
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.Ed |
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.Bl -column "XXXX-XX-XX" "HH:MM:SS" "-HH:MM:SS" "TZT" "X" -compact |
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.It - Ta - Ta +03:12:12 Ta LMT Ta |
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.It 1924-04-30 Ta 23:47:48 Ta +03 Ta Ta |
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.It 1930-06-21 Ta 01 Ta +04 Ta Ta |
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.It 1981-04-01 Ta 01 Ta +05 Ta Ta 1 |
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.It 1981-09-30 Ta 23 Ta +04 Ta Ta |
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.It \&... Ta Ta Ta Ta |
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.It 2014-10-26 Ta 01 Ta +03 Ta Ta |
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.It 2016-03-27 Ta 03 Ta +04 Ta Ta |
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.El |
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.Pp |
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This time zone is east of UT, so its UT offsets are positive. Also, |
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many of its time zone abbreviations are omitted since they duplicate |
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the text of the UT offset. |
.Sh LIMITATIONS |
.Sh LIMITATIONS |
Time discontinuities are found by sampling the results returned by localtime |
Time discontinuities are found by sampling the results returned by localtime |
at twelve-hour intervals. |
at twelve-hour intervals. |
This works in all real-world cases; |
This works in all real-world cases; |
one can construct artificial time zones for which this fails. |
one can construct artificial time zones for which this fails. |
.Pp |
.Pp |
In the output, |
In the |
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.Fl v |
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and |
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.Fl V |
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output, |
.Dq UT |
.Dq UT |
denotes the value returned by |
denotes the value returned by |
.Xr gmtime 3 , |
.Xr gmtime 3 , |
Line 92 No attempt is currently made to have the |
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Line 206 No attempt is currently made to have the |
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.Dq UTC |
.Dq UTC |
for newer and |
for newer and |
.Dq UT |
.Dq UT |
for older time stamps, |
for older time stamps, partly because the exact date of the |
partly because the exact date of the introduction of UTC is problematic. |
introduction of UTC is problematic. |
.Sh SEE ALSO |
.Sh SEE ALSO |
.Xr ctime 3 , |
.Xr ctime 3 , |
.Xr tzfile 5 , |
.Xr tzfile 5 , |