diff options
Diffstat (limited to 'man8/zic.8')
| -rw-r--r-- | man8/zic.8 | 139 |
1 files changed, 65 insertions, 74 deletions
diff --git a/man8/zic.8 b/man8/zic.8 index 557ccd282..0ad373a2d 100644 --- a/man8/zic.8 +++ b/man8/zic.8 @@ -95,7 +95,7 @@ as local time. .B zic will act as if the input contained a link line of the form .sp -.ti +.5i +.ti +2 .ta \w'Link\0\0'u +\w'\fItimezone\fP\0\0'u Link \fItimezone\fP localtime .sp @@ -118,9 +118,15 @@ 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 +.ti +2 Link \fItimezone\fP posixrules .sp +If +.I timezone +is +.q "\*-" +(the default), any already-existing link is removed. +.sp Unless .I timezone is .q "\*-" , @@ -131,12 +137,6 @@ and it should not be combined with if .IR timezone 's transitions are at standard time or Universal Time (UT) instead of local time. -.sp -If -.I timezone -is -.BR \*- , -any already-existing link is removed. .TP .BR "\*-r " "[\fB@\fP\fIlo\fP][\fB/@\fP\fIhi\fP]" Limit the applicability of output files @@ -171,7 +171,7 @@ boundaries, particularly if causes a TZif file to contain explicit entries for .RI pre- hi transitions rather than concisely representing them -with an extended POSIX TZ string. +with an extended POSIX.1-2017 TZ string. Also see the .B "\*-b slim" option for another way to shrink output size. @@ -181,10 +181,10 @@ Generate redundant trailing explicit transitions for timestamps that occur less than .I hi seconds since the Epoch, even though the transitions could be -more concisely represented via the extended POSIX TZ string. +more concisely represented via the extended POSIX.1-2017 TZ string. This option does not affect the represented timestamps. Although it accommodates nonstandard TZif readers -that ignore the extended POSIX TZ string, +that ignore the extended POSIX.1-2017 TZ string, it increases the size of the altered output files. .TP .BI "\*-t " file @@ -194,37 +194,37 @@ the named file rather than in the standard location. .B \*-v Be more verbose, and complain about the following situations: .RS -.P +.PP The input specifies a link to a link, something not supported by some older parsers, including .B zic itself through release 2022e. -.P +.PP A year that appears in a data file is outside the range of representable years. -.P +.PP A time of 24:00 or more appears in the input. Pre-1998 versions of .B zic prohibit 24:00, and pre-2007 versions prohibit times greater than 24:00. -.P +.PP A rule goes past the start or end of the month. Pre-2004 versions of .B zic prohibit this. -.P +.PP A time zone abbreviation uses a .B %z format. Pre-2015 versions of .B zic do not support this. -.P +.PP A timestamp contains fractional seconds. Pre-2018 versions of .B zic do not support this. -.P +.PP The input contains abbreviations that are mishandled by pre-2018 versions of .B zic due to a longstanding coding bug. @@ -242,20 +242,20 @@ and .q Su for .q Sun . -.P +.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 2023 this problem +an extended POSIX.1-2017 TZ string. For example, as of 2023 this problem occurs for Morocco's daylight-saving rules, as these rules are based on predictions for when Ramadan will be observed, something that -an extended POSIX TZ string cannot represent. -.P +an extended POSIX.1-2017 TZ string cannot represent. +.PP The output contains data that may not be handled properly by client code designed for older .B zic output formats. These compatibility issues affect only timestamps before 1970 or after the start of 2038. -.P +.PP The output contains a truncated leap second table, which can cause some older TZif readers to misbehave. This can occur if the @@ -264,17 +264,17 @@ option is used, and either an Expires line is present or the .B "\*-r" option is also used. -.P +.PP 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. -.P +.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. -.P +.PP An output file name contains a byte that is not an ASCII letter, .q "\*-" , .q "/" , @@ -288,7 +288,7 @@ or that starts with Input files use the format described in this section; output files use .BR tzfile (5) format. -.P +.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 most 2048 bytes counting the newline, and without any NUL bytes. @@ -303,7 +303,7 @@ nearly any character, other software will work better if these are limited to the restricted syntax described under the .B \*-v option. -.P +.PP Input lines are made up of fields. Fields are separated from one another by one or more white space characters. The white space characters are space, form feed, carriage return, newline, @@ -316,7 +316,7 @@ White space characters and sharp characters may be enclosed in double quotes Any line that is blank (after comment stripping) is ignored. Nonblank lines are expected to be of one of three types: rule lines, zone lines, and link lines. -.P +.PP Names must be in English and are case insensitive. They appear in several contexts, and include month and weekday names and keywords such as @@ -327,22 +327,22 @@ and .BR "Zone" . A name can be abbreviated by omitting all but an initial prefix; any abbreviation must be unambiguous in context. -.P +.PP A rule line has the form .nf -.ti +.5i +.ti +2 .ta \w'Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'1973\0\0'u +\w'\*-\0\0'u +\w'Apr\0\0'u +\w'lastSun\0\0'u +\w'2:00w\0\0'u +\w'1:00d\0\0'u .sp Rule NAME FROM TO \*- IN ON AT SAVE LETTER/S .sp For example: -.ti +.5i +.ti +2 .sp Rule US 1967 1973 \*- Apr lastSun 2:00w 1:00d D .sp .fi The fields that make up a rule line are: -.TP "\w'LETTER/S'u" +.TP .B NAME Gives the name of the rule set that contains this line. The name must start with a character that is neither @@ -360,24 +360,15 @@ an unquoted name should not contain characters from the set Gives the first year in which the rule applies. Any signed integer year can be supplied; the proleptic Gregorian calendar is assumed, with year 0 preceding year 1. -The word -.B minimum -(or an abbreviation) means the indefinite past. -The word -.B maximum -(or an abbreviation) means the indefinite future. Rules can describe times that are not representable as time values, with the unrepresentable times ignored; this allows rules to be portable among hosts with differing time value types. .TP .B TO Gives the final year in which the rule applies. -In addition to -.B minimum -and +The word .B maximum -(as above), -the word +(or an abbreviation) means the indefinite future, and the word .B only (or an abbreviation) may be used to repeat the value of the @@ -404,7 +395,7 @@ Month names may be abbreviated. Gives the day on which the rule takes effect. Recognized forms include: .nf -.in +.5i +.in +2 .sp .ta \w'Sun<=25\0\0'u 5 the fifth of the month @@ -413,7 +404,7 @@ lastMon the last Monday in the month Sun>=8 first Sunday on or after the eighth Sun<=25 last Sunday on or before the 25th .fi -.in -.5i +.in .sp A weekday name (e.g., .BR "Sunday" ) @@ -440,7 +431,7 @@ 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 +.in +2 .sp .ta \w'00:19:32.13\0\0'u 2 time in hours @@ -454,7 +445,7 @@ Recognized forms include: \*-2:30 2.5 hours before 00:00 \*- equivalent to 0 .fi -.in -.5i +.in .sp Although .B zic @@ -528,22 +519,22 @@ of time zone abbreviations to be used when this rule is in effect. If this field is .q \*- , the variable part is null. -.P +.PP A zone line has the form .sp .nf -.ti +.5i +.ti +2 .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 -.ti +.5i +.ti +2 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'STDOFF'u" +.TP .B NAME The name of the timezone. This is the name used in creating the time conversion information file for the @@ -632,7 +623,7 @@ Continuation lines may contain .q "until" information, just as zone lines do, indicating that the next line is a further continuation. -.P +.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 @@ -647,7 +638,7 @@ earliest rule use the rule in effect after 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. -.P +.PP If a continuation line subtracts .I N seconds from the UT offset after a transition that would be @@ -663,15 +654,15 @@ For example: .br .ne 7 .nf -.in +2m +.in +2 .ta \w'# Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'2006\0\0'u +\w'\*-\0\0'u +\w'Oct\0\0'u +\w'lastSun\0\0'u +\w'2:00\0\0'u +\w'SAVE\0\0'u .sp # Rule NAME FROM TO \*- IN ON AT SAVE LETTER/S Rule US 1967 2006 - Oct lastSun 2:00 0 S Rule US 1967 1973 - Apr lastSun 2:00 1:00 D -.ta \w'Zone\0\0America/Menominee\0\0'u +\w'STDOFF\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u -# Zone\0\0NAME STDOFF RULES FORMAT [UNTIL] -Zone\0\0America/Menominee \*-5:00 \*- EST 1973 Apr 29 2:00 +.ta \w'# Zone\0\0'u +\w'America/Menominee\0\0'u +\w'STDOFF\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u +# Zone NAME STDOFF RULES FORMAT [UNTIL] +Zone America/Menominee \*-5:00 \*- EST 1973 Apr 29 2:00 \*-6:00 US C%sT .sp .in @@ -683,17 +674,17 @@ However, .B zic interprets this more sensibly as a single transition from 02:00 CST (\*-05) to 02:00 CDT (\*-05). -.P +.PP A link line has the form .sp .nf -.ti +.5i +.ti +2 .ta \w'Link\0\0'u +\w'Europe/Istanbul\0\0'u Link TARGET LINK-NAME .sp For example: .sp -.ti +.5i +.ti +2 Link Europe/Istanbul Asia/Istanbul .sp .fi @@ -717,7 +708,7 @@ For example: .sp .ne 3 .nf -.in +2m +.in +2 .ta \w'Zone\0\0'u +\w'Greenwich\0\0'u Link Greenwich G_M_T Link Etc/GMT Greenwich @@ -727,23 +718,23 @@ Zone Etc/GMT\0\00\0\0\*-\0\0GMT .fi The two links are chained together, and G_M_T, Greenwich, and Etc/GMT all name the same zone. -.P +.PP Except for continuation lines, lines may appear in any order in the input. However, the behavior is unspecified if multiple zone or link lines define the same name. -.P +.PP The file that describes leap seconds can have leap lines and an expiration line. Leap lines have the following form: .nf -.ti +.5i +.ti +2 .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 .sp Leap YEAR MONTH DAY HH:MM:SS CORR R/S .sp For example: -.ti +.5i +.ti +2 .sp Leap 2016 Dec 31 23:59:60 + S .sp @@ -775,7 +766,7 @@ or .q "Rolling" if the leap second time given by the other fields should be interpreted as local (wall clock) time. -.P +.PP Rolling leap seconds were implemented back when it was not clear whether common practice was rolling or stationary, with concerns that one would see @@ -788,16 +779,16 @@ which means rolling leap seconds are not used in practice; also, they are not supported if the .B \*-r option is used. -.P +.PP The expiration line, if present, has the form: .nf -.ti +.5i +.ti +2 .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 +.ti +2 .sp Expires 2020 Dec 28 00:00:00 .sp @@ -816,7 +807,7 @@ Here is an extended example of .B zic input, intended to illustrate many of its features. .nf -.in +2m +.in +2 .ta \w'# Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'1973\0\0'u +\w'\*-\0\0'u +\w'Apr\0\0'u +\w'lastSun\0\0'u +\w'2:00\0\0'u +\w'SAVE\0\0'u .sp # Rule NAME FROM TO \*- IN ON AT SAVE LETTER/S @@ -856,7 +847,7 @@ and Swiss daylight saving rules (defined with lines beginning with .q "Rule Swiss") apply. From 1981 to the present, EU daylight saving rules have applied, and the UTC offset has remained at one hour. -.P +.PP In 1941 and 1942, daylight saving time applied from the first Monday in May at 01:00 to the first Monday in October at 02:00. The pre-1981 EU daylight-saving rules have no effect @@ -864,7 +855,7 @@ here, but are included for completeness. Since 1981, daylight saving has begun on the last Sunday in March at 01:00 UTC. Until 1995 it ended the last Sunday in September at 01:00 UTC, but this changed to the last Sunday in October starting in 1996. -.P +.PP For purposes of display, .q "LMT" and @@ -886,7 +877,7 @@ you may need to use local standard time in the .B AT field of the earliest transition time's rule to ensure that the earliest transition time recorded in the compiled file is correct. -.P +.PP If, for a particular timezone, a clock advance caused by the start of daylight saving |