mirror of https://github.com/mkerrisk/man-pages
zic.8: Sync to 2020a tzdb release
From https://www.iana.org/time-zones, version 2020a. Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk
parent
f4077c2c2c
commit
24e14ed0b3
288
man8/zic.8
288
man8/zic.8
|
|
@ -2,7 +2,7 @@
|
|||
.\" This page is in the public domain
|
||||
.\" %%%LICENSE_END
|
||||
.\"
|
||||
.TH ZIC 8 2019-03-06 "" "Linux System Administration"
|
||||
.TH ZIC 8 2020-04-27 "" "Linux System Administration"
|
||||
.SH NAME
|
||||
zic \- timezone compiler
|
||||
.SH SYNOPSIS
|
||||
|
|
@ -49,6 +49,32 @@ Output version information and exit.
|
|||
.B \*-\*-help
|
||||
Output short usage message and exit.
|
||||
.TP
|
||||
.BI "\*-b " bloat
|
||||
Output backward-compatibility data as specified by
|
||||
.IR bloat .
|
||||
If
|
||||
.I bloat
|
||||
is
|
||||
.BR fat ,
|
||||
generate additional data entries that work around potential bugs or
|
||||
incompatibilities in older software, such as software that mishandles
|
||||
the 64-bit generated data.
|
||||
If
|
||||
.I bloat
|
||||
is
|
||||
.BR slim ,
|
||||
keep the output files small; this can help check for the bugs
|
||||
and incompatibilities.
|
||||
Although the default is currently
|
||||
.BR fat ,
|
||||
this is intended to change in future
|
||||
.B zic
|
||||
versions, as software that mishandles the 64-bit data typically
|
||||
mishandles timestamps after the year 2038 anyway.
|
||||
Also see the
|
||||
.B \*-r
|
||||
option for another way to shrink output size.
|
||||
.TP
|
||||
.BI "\*-d " directory
|
||||
Create time conversion information files in the named directory rather than
|
||||
in the standard directory named below.
|
||||
|
|
@ -61,24 +87,64 @@ as local time.
|
|||
will act as if the input contained a link line of the form
|
||||
.sp
|
||||
.ti +.5i
|
||||
.ta \w'Link\0\0'u +\w'\fItimezone\fP\0\0'u
|
||||
Link \fItimezone\fP localtime
|
||||
.TP
|
||||
.BI "\*-p " timezone
|
||||
Use
|
||||
.IR timezone 's
|
||||
rules when handling POSIX-format
|
||||
timezone environment variables.
|
||||
.B zic
|
||||
will act as if the input contained a link line of the form
|
||||
.sp
|
||||
.ti +.5i
|
||||
Link \fItimezone\fP posixrules
|
||||
.TP
|
||||
.BI "\*-L " leapsecondfilename
|
||||
Read leap second information from the file with the given name.
|
||||
If this option is not used,
|
||||
no leap second information appears in output files.
|
||||
.TP
|
||||
.BI "\*-p " timezone
|
||||
Use
|
||||
.IR timezone 's
|
||||
rules when handling nonstandard
|
||||
TZ strings like "EET\*-2EEST" that lack transition rules.
|
||||
.B zic
|
||||
will act as if the input contained a link line of the form
|
||||
.sp
|
||||
.ti +.5i
|
||||
Link \fItimezone\fP posixrules
|
||||
.sp
|
||||
This feature is obsolete and poorly supported.
|
||||
Among other things it should not be used for timestamps after the year 2037,
|
||||
and it should not be combined with
|
||||
.B "\*-b slim"
|
||||
if
|
||||
.IR timezone 's
|
||||
transitions are at standard time or Universal Time (UT) instead of local time.
|
||||
.TP
|
||||
.BR "\*-r " "[\fB@\fP\fIlo\fP][\fB/@\fP\fIhi\fP]"
|
||||
Reduce the size of output files by limiting their applicability
|
||||
to timestamps in the range from
|
||||
.I lo
|
||||
(inclusive) to
|
||||
.I hi
|
||||
(exclusive), where
|
||||
.I lo
|
||||
and
|
||||
.I hi
|
||||
are possibly-signed decimal counts of seconds since the Epoch
|
||||
(1970-01-01 00:00:00 UTC).
|
||||
Omitted counts default to extreme values.
|
||||
For example,
|
||||
.q "zic \*-r @0"
|
||||
omits data intended for negative timestamps (i.e., before the Epoch), and
|
||||
.q "zic \*-r @0/@2147483648"
|
||||
outputs data intended only for nonnegative timestamps that fit into
|
||||
31-bit signed integers.
|
||||
On platforms with GNU
|
||||
.BR date ,
|
||||
.q "zic \-r @$(date +%s)"
|
||||
omits data intended for past timestamps.
|
||||
Also see the
|
||||
.B "\*-b slim"
|
||||
option for another way to shrink output size.
|
||||
.TP
|
||||
.BI "\*-t " file
|
||||
When creating local time information, put the configuration link in
|
||||
the named file rather than in the standard location.
|
||||
.TP
|
||||
.B \*-v
|
||||
Be more verbose, and complain about the following situations:
|
||||
.RS
|
||||
|
|
@ -86,9 +152,7 @@ Be more verbose, and complain about the following situations:
|
|||
The input specifies a link to a link.
|
||||
.PP
|
||||
A year that appears in a data file is outside the range
|
||||
of years representable by
|
||||
.BR time (2)
|
||||
values.
|
||||
of representable years.
|
||||
.PP
|
||||
A time of 24:00 or more appears in the input.
|
||||
Pre-1998 versions of
|
||||
|
|
@ -100,9 +164,39 @@ Pre-2004 versions of
|
|||
.B zic
|
||||
prohibit this.
|
||||
.PP
|
||||
A time zone abbreviation uses a
|
||||
.B %z
|
||||
format.
|
||||
Pre-2015 versions of
|
||||
.B zic
|
||||
do not support this.
|
||||
.PP
|
||||
A timestamp contains fractional seconds.
|
||||
Pre-2018 versions of
|
||||
.B zic
|
||||
do not support this.
|
||||
.PP
|
||||
The input contains abbreviations that are mishandled by pre-2018 versions of
|
||||
.B zic
|
||||
due to a longstanding coding bug.
|
||||
These abbreviations include
|
||||
.q L
|
||||
for
|
||||
.q Link ,
|
||||
.q mi
|
||||
for
|
||||
.q min ,
|
||||
.q Sa
|
||||
for
|
||||
.q Sat ,
|
||||
and
|
||||
.q Su
|
||||
for
|
||||
.q Sun .
|
||||
.PP
|
||||
The output file does not contain all the information about the
|
||||
long-term future of a timezone, because the future cannot be summarized as
|
||||
an extended POSIX TZ string. For example, as of 2013 this problem
|
||||
an extended POSIX TZ string. For example, as of 2019 this problem
|
||||
occurs for Iran's daylight-saving rules for the predicted future, as
|
||||
these rules are based on the Iranian calendar, which cannot be
|
||||
represented.
|
||||
|
|
@ -113,8 +207,15 @@ code designed for older
|
|||
output formats. These compatibility issues affect only timestamps
|
||||
before 1970 or after the start of 2038.
|
||||
.PP
|
||||
A time zone abbreviation has fewer than 3 characters.
|
||||
POSIX requires at least 3.
|
||||
The output file contains more than 1200 transitions,
|
||||
which may be mishandled by some clients.
|
||||
The current reference client supports at most 2000 transitions;
|
||||
pre-2014 versions of the reference client support at most 1200
|
||||
transitions.
|
||||
.PP
|
||||
A time zone abbreviation has fewer than 3 or more than 6 characters.
|
||||
POSIX requires at least 3, and requires implementations to support
|
||||
at least 6.
|
||||
.PP
|
||||
An output file name contains a byte that is not an ASCII letter,
|
||||
.q "\*-" ,
|
||||
|
|
@ -125,11 +226,10 @@ or it contains a file name component that contains more than 14 bytes
|
|||
or that starts with
|
||||
.q "\*-" .
|
||||
.RE
|
||||
.TP
|
||||
.B \*-s
|
||||
Limit time values stored in output files to values that are the same
|
||||
whether they're taken to be signed or unsigned.
|
||||
You can use this option to generate SVVS-compatible files.
|
||||
.SH FILES
|
||||
Input files use the format described in this section; output files use
|
||||
.IR tzfile (5)
|
||||
format.
|
||||
.PP
|
||||
Input files should be text files, that is, they should be a series of
|
||||
zero or more lines, each ending in a newline byte and containing at
|
||||
|
|
@ -179,7 +279,7 @@ Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
|
|||
For example:
|
||||
.ti +.5i
|
||||
.sp
|
||||
Rule US 1967 1973 \*- Apr lastSun 2:00w 1:00 D
|
||||
Rule US 1967 1973 \*- Apr lastSun 2:00w 1:00d D
|
||||
.sp
|
||||
.fi
|
||||
The fields that make up a rule line are:
|
||||
|
|
@ -256,12 +356,22 @@ or a weekday name preceded by
|
|||
(e.g.,
|
||||
.BR "lastSunday" )
|
||||
may be abbreviated or spelled out in full.
|
||||
Note that there must be no spaces within the
|
||||
There must be no white space characters within the
|
||||
.B ON
|
||||
field.
|
||||
The
|
||||
.q <=
|
||||
and
|
||||
.q >=
|
||||
constructs can result in a day in the neighboring month;
|
||||
for example, the IN-ON combination
|
||||
.q "Oct Sun>=31"
|
||||
stands for the first Sunday on or after October 31,
|
||||
even if that Sunday occurs in November.
|
||||
.TP
|
||||
.B AT
|
||||
Gives the time of day at which the rule takes effect.
|
||||
Gives the time of day at which the rule takes effect,
|
||||
relative to 00:00, the start of a calendar day.
|
||||
Recognized forms include:
|
||||
.nf
|
||||
.in +.5i
|
||||
|
|
@ -270,24 +380,30 @@ Recognized forms include:
|
|||
2 time in hours
|
||||
2:00 time in hours and minutes
|
||||
01:28:14 time in hours, minutes, and seconds
|
||||
15:00 24-hour format time (for times after noon)
|
||||
00:19:32.13 time with fractional seconds
|
||||
12:00 midday, 12 hours after 00:00
|
||||
15:00 3 PM, 15 hours after 00:00
|
||||
24:00 end of day, 24 hours after 00:00
|
||||
260:00 260 hours after 00:00
|
||||
\*-2:30 2.5 hours before 00:00
|
||||
\*- equivalent to 0
|
||||
.fi
|
||||
.in -.5i
|
||||
.sp
|
||||
where hour 0 is midnight at the start of the day,
|
||||
and hour 24 is midnight at the end of the day.
|
||||
Although
|
||||
.B zic
|
||||
rounds times to the nearest integer second
|
||||
(breaking ties to the even integer), the fractions may be useful
|
||||
to other applications requiring greater precision.
|
||||
The source format does not specify any maximum precision.
|
||||
Any of these forms may be followed by the letter
|
||||
.B w
|
||||
if the given time is local
|
||||
if the given time is local or
|
||||
.q "wall clock"
|
||||
time,
|
||||
.B s
|
||||
if the given time is local
|
||||
.q "standard"
|
||||
time, or
|
||||
if the given time is standard time without any adjustment for daylight saving,
|
||||
or
|
||||
.B u
|
||||
(or
|
||||
.B g
|
||||
|
|
@ -295,7 +411,11 @@ or
|
|||
.BR z )
|
||||
if the given time is universal time;
|
||||
in the absence of an indicator,
|
||||
wall clock time is assumed.
|
||||
local (wall clock) time is assumed.
|
||||
These forms ignore leap seconds; for example,
|
||||
if a leap second occurs at 00:59:60 local time,
|
||||
.q "1:00"
|
||||
stands for 3601 seconds after local midnight instead of the usual 3600 seconds.
|
||||
The intent is that a rule line describes the instants when a
|
||||
clock/calendar set to the type of time specified in the
|
||||
.B AT
|
||||
|
|
@ -303,15 +423,20 @@ field would show the specified date and time of day.
|
|||
.TP
|
||||
.B SAVE
|
||||
Gives the amount of time to be added to local standard time when the rule is in
|
||||
effect.
|
||||
effect, and whether the resulting time is standard or daylight saving.
|
||||
This field has the same format as the
|
||||
.B AT
|
||||
field
|
||||
(although, of course, the
|
||||
.B w
|
||||
and
|
||||
except with a different set of suffix letters:
|
||||
.B s
|
||||
suffixes are not used).
|
||||
for standard time and
|
||||
.B d
|
||||
for daylight saving time.
|
||||
The suffix letter is typically omitted, and defaults to
|
||||
.B s
|
||||
if the offset is zero and to
|
||||
.B d
|
||||
otherwise.
|
||||
Negative offsets are allowed; in Ireland, for example, daylight saving
|
||||
time is observed in winter and has a negative offset relative to
|
||||
Irish Standard Time.
|
||||
|
|
@ -342,8 +467,8 @@ A zone line has the form
|
|||
.sp
|
||||
.nf
|
||||
.ti +.5i
|
||||
.ta \w'Zone\0\0'u +\w'Asia/Amman\0\0'u +\w'UTOFF\0\0'u +\w'Jordan\0\0'u +\w'FORMAT\0\0'u
|
||||
Zone NAME UTOFF RULES FORMAT [UNTIL]
|
||||
.ta \w'Zone\0\0'u +\w'Asia/Amman\0\0'u +\w'STDOFF\0\0'u +\w'Jordan\0\0'u +\w'FORMAT\0\0'u
|
||||
Zone NAME STDOFF RULES FORMAT [UNTIL]
|
||||
.sp
|
||||
For example:
|
||||
.sp
|
||||
|
|
@ -352,7 +477,7 @@ Zone Asia/Amman 2:00 Jordan EE%sT 2017 Oct 27 01:00
|
|||
.sp
|
||||
.fi
|
||||
The fields that make up a zone line are:
|
||||
.TP "\w'UTOFF'u"
|
||||
.TP "\w'STDOFF'u"
|
||||
.B NAME
|
||||
The name of the timezone.
|
||||
This is the name used in creating the time conversion information file for the
|
||||
|
|
@ -364,8 +489,9 @@ or
|
|||
a file name component is a maximal substring that does not contain
|
||||
.q "/" .
|
||||
.TP
|
||||
.B UTOFF
|
||||
The amount of time to add to UT to get standard time.
|
||||
.B STDOFF
|
||||
The amount of time to add to UT to get standard time,
|
||||
without any adjustment for daylight saving.
|
||||
This field has the same format as the
|
||||
.B AT
|
||||
and
|
||||
|
|
@ -415,7 +541,7 @@ and
|
|||
.TP
|
||||
.B UNTIL
|
||||
The time at which the UT offset or the rule(s) change for a location.
|
||||
It takes the form of YEAR [MONTH [DAY [TIME]]].
|
||||
It takes the form of one to four fields YEAR [MONTH [DAY [TIME]]].
|
||||
If this is specified,
|
||||
the time zone information is generated from the given UT offset
|
||||
and rule change until the time specified, which is interpreted using
|
||||
|
|
@ -440,6 +566,16 @@ continuation.
|
|||
.PP
|
||||
If a zone changes at the same instant that a rule would otherwise take
|
||||
effect in the earlier zone or continuation line, the rule is ignored.
|
||||
A zone or continuation line
|
||||
.I L
|
||||
with a named rule set starts with standard time by default:
|
||||
that is, any of
|
||||
.IR L 's
|
||||
timestamps preceding
|
||||
.IR L 's
|
||||
earliest rule use the rule in effect after
|
||||
.IR L 's
|
||||
first transition into standard time.
|
||||
In a single zone it is an error if two rules take effect at the same
|
||||
instant, or if two zone changes take effect at the same instant.
|
||||
.PP
|
||||
|
|
@ -474,7 +610,9 @@ However, the behavior is unspecified if multiple zone or link lines
|
|||
define the same name, or if the source of one link line is the target
|
||||
of another.
|
||||
.PP
|
||||
Lines in the file that describes leap seconds have the following form:
|
||||
The file that describes leap seconds can have leap lines and an
|
||||
expiration line.
|
||||
Leap lines have the following form:
|
||||
.nf
|
||||
.ti +.5i
|
||||
.ta \w'Leap\0\0'u +\w'YEAR\0\0'u +\w'MONTH\0\0'u +\w'DAY\0\0'u +\w'HH:MM:SS\0\0'u +\w'CORR\0\0'u
|
||||
|
|
@ -513,7 +651,44 @@ or
|
|||
(an abbreviation of)
|
||||
.q "Rolling"
|
||||
if the leap second time given by the other fields should be interpreted as
|
||||
local wall clock time.
|
||||
local (wall clock) time.
|
||||
.PP
|
||||
The expiration line, if present, has the form:
|
||||
.nf
|
||||
.ti +.5i
|
||||
.ta \w'Expires\0\0'u +\w'YEAR\0\0'u +\w'MONTH\0\0'u +\w'DAY\0\0'u
|
||||
.sp
|
||||
Expires YEAR MONTH DAY HH:MM:SS
|
||||
.sp
|
||||
For example:
|
||||
.ti +.5i
|
||||
.sp
|
||||
Expires 2020 Dec 28 00:00:00
|
||||
.sp
|
||||
.fi
|
||||
The
|
||||
.BR YEAR ,
|
||||
.BR MONTH ,
|
||||
.BR DAY ,
|
||||
and
|
||||
.B HH:MM:SS
|
||||
fields give the expiration timestamp in UTC for the leap second table;
|
||||
.B zic
|
||||
outputs this expiration timestamp by truncating the end of the output
|
||||
file to the timestamp.
|
||||
If there is no expiration line,
|
||||
.B zic
|
||||
also accepts a comment
|
||||
.q "#expires \fIE\fP ...\&"
|
||||
where
|
||||
.I E
|
||||
is the expiration timestamp as a decimal integer count of seconds
|
||||
since the Epoch, not counting leap seconds.
|
||||
However, the
|
||||
.q "#expires"
|
||||
comment is an obsolescent feature,
|
||||
and the leap second file should use an expiration line
|
||||
instead of relying on a comment.
|
||||
.SH "EXTENDED EXAMPLE"
|
||||
Here is an extended example of
|
||||
.B zic
|
||||
|
|
@ -537,10 +712,10 @@ Rule EU 1979 1995 \*- Sep lastSun 1:00u 0 \*-
|
|||
Rule EU 1981 max \*- Mar lastSun 1:00u 1:00 S
|
||||
Rule EU 1996 max \*- Oct lastSun 1:00u 0 \*-
|
||||
.sp
|
||||
.ta \w'# Zone\0\0'u +\w'Europe/Zurich\0\0'u +\w'0:34:08\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u
|
||||
# Zone NAME UTOFF RULES FORMAT [UNTIL]
|
||||
.ta \w'# Zone\0\0'u +\w'Europe/Zurich\0\0'u +\w'0:29:45.50\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u
|
||||
# Zone NAME STDOFF RULES FORMAT [UNTIL]
|
||||
Zone Europe/Zurich 0:34:08 \*- LMT 1853 Jul 16
|
||||
0:29:46 \*- BMT 1894 Jun
|
||||
0:29:45.50 \*- BMT 1894 Jun
|
||||
1:00 Swiss CE%sT 1981
|
||||
1:00 EU CE%sT
|
||||
.sp
|
||||
|
|
@ -551,9 +726,14 @@ Link Europe/Zurich Europe/Vaduz
|
|||
In this example, the timezone is named Europe/Zurich but it has an alias
|
||||
as Europe/Vaduz. This example says that Zurich was 34 minutes and 8
|
||||
seconds east of UT until 1853-07-16 at 00:00, when the legal offset
|
||||
was changed to 7\(de\|26\(fm\|22.50\(sd; although this works out to
|
||||
0:29:45.50, the input format cannot represent fractional seconds so it
|
||||
is rounded here. After 1894-06-01 at 00:00 the UT offset became one hour
|
||||
was changed to
|
||||
.ds o 7 degrees 26 minutes 22.50 seconds
|
||||
.if \n(.g .if c \(de .if c \(fm .if c \(sd .ds o 7\(de\|26\(fm\|22.50\(sd
|
||||
\*o,
|
||||
which works out to 0:29:45.50;
|
||||
.B zic
|
||||
treats this by rounding it to 0:29:46.
|
||||
After 1894-06-01 at 00:00 the UT offset became one hour
|
||||
and Swiss daylight saving rules (defined with lines beginning with
|
||||
.q "Rule Swiss")
|
||||
apply. From 1981 to the present, EU daylight saving rules have
|
||||
|
|
@ -596,7 +776,7 @@ coincides with and is equal to
|
|||
a clock retreat caused by a change in UT offset,
|
||||
.B zic
|
||||
produces a single transition to daylight saving at the new UT offset
|
||||
(without any change in wall clock time).
|
||||
without any change in local (wall clock) time.
|
||||
To get separate transitions
|
||||
use multiple zone continuation lines
|
||||
specifying transition instants using universal time.
|
||||
|
|
|
|||
Loading…
Reference in New Issue