Changeset View
Changeset View
Standalone View
Standalone View
contrib/tzcode/zic.8
.\" This file is in the public domain, so clarified as of | .\" This file is in the public domain, so clarified as of | ||||
.\" 2009-05-17 by Arthur David Olson. | .\" 2009-05-17 by Arthur David Olson. | ||||
.\" | |||||
.\" $FreeBSD$ | |||||
.\" | |||||
.Dd January 21, 2023 | .Dd January 21, 2023 | ||||
.Dt ZIC 8 | .Dt ZIC 8 | ||||
.Os | .Os | ||||
.Sh NAME | .Sh NAME | ||||
.Nm zic | .Nm zic | ||||
.Nd timezone compiler | .Nd timezone compiler | ||||
.Sh SYNOPSIS | .Sh SYNOPSIS | ||||
.Nm | .Nm | ||||
▲ Show 20 Lines • Show All 93 Lines • ▼ Show 20 Lines | |||||
The | The | ||||
.Nm | .Nm | ||||
utility | utility | ||||
will act as if the input contained a link line of the form | will act as if the input contained a link line of the form | ||||
.Bd -literal -offset indent | .Bd -literal -offset indent | ||||
Link \fItimezone\fP posixrules | Link \fItimezone\fP posixrules | ||||
.Ed | .Ed | ||||
.Pp | .Pp | ||||
This feature is obsolete and poorly supported. | Unless | ||||
.Ar timezone | |||||
is | |||||
.Dq "\*-" , | |||||
this option is obsolete and poorly supported. | |||||
Among other things it should not be used for timestamps after the year 2037, | Among other things it should not be used for timestamps after the year 2037, | ||||
and it should not be combined with | and it should not be combined with | ||||
.Fl b Cm slim | .Fl b Cm slim | ||||
if | if | ||||
.Ar timezone 's | .Ar timezone 's | ||||
transitions are at standard time or Universal Time (UT) instead of local time. | transitions are at standard time or Universal Time (UT) instead of local time. | ||||
.Pp | .Pp | ||||
If | If | ||||
.Ar timezone | .Ar timezone | ||||
is | is | ||||
.Ql - , | .Ql - , | ||||
any already-existing link is removed. | any already-existing link is removed. | ||||
.It Fl r Oo @ Ns Ar lo Oc Ns Oo /@ Ns Ar hi Oc | .It Fl r Oo @ Ns Ar lo Oc Ns Oo /@ Ns Ar hi Oc | ||||
Limit the applicability of output files | Limit the applicability of output files | ||||
to timestamps in the range from | to timestamps in the range from | ||||
.Ar lo | .Ar lo | ||||
(inclusive) to | (inclusive) to | ||||
.Ar hi | .Ar hi | ||||
(exclusive), where | (exclusive), where | ||||
.Ar lo | .Ar lo | ||||
and | and | ||||
.Ar hi | .Ar hi | ||||
are possibly-signed decimal counts of seconds since the Epoch | are possibly signed decimal counts of seconds since the Epoch | ||||
(1970-01-01 00:00:00 UTC). | (1970-01-01 00:00:00 UTC). | ||||
Omitted counts default to extreme values. | Omitted counts default to extreme values. | ||||
The output files use UT offset 0 and abbreviation | The output files use UT offset 0 and abbreviation | ||||
.Dq "\-00" | .Dq "\-00" | ||||
in place of the omitted timestamp data. | in place of the omitted timestamp data. | ||||
For example, | For example, | ||||
.Fl r @0 | .Fl r @0 | ||||
omits data intended for negative timestamps (i.e., before the Epoch), and | omits data intended for negative timestamps (i.e., before the Epoch), and | ||||
▲ Show 20 Lines • Show All 75 Lines • ▼ Show 20 Lines | |||||
and | and | ||||
.Dq Su | .Dq Su | ||||
for | for | ||||
.Dq Sun . | .Dq Sun . | ||||
.It | .It | ||||
The output file does not contain all the information about the | The output file does not contain all the information about the | ||||
long-term future of a timezone, because the future cannot be summarized as | long-term future of a timezone, because the future cannot be summarized as | ||||
an extended POSIX TZ string. | an extended POSIX TZ string. | ||||
For example, as of 2019 this problem | For example, as of 2023 this problem | ||||
occurs for Iran's daylight-saving rules for the predicted future, as | occurs for Morocco's daylight-saving rules, as these rules are based | ||||
these rules are based on the Iranian calendar, which cannot be | on predictions for when Ramadan will be observed, something that | ||||
represented. | an extended POSIX TZ string cannot represent. | ||||
.It | .It | ||||
The output contains data that may not be handled properly by client | The output contains data that may not be handled properly by client | ||||
code designed for older | code designed for older | ||||
.Nm | .Nm | ||||
output formats. | output formats. | ||||
These compatibility issues affect only timestamps | These compatibility issues affect only timestamps | ||||
before 1970 or after the start of 2038. | before 1970 or after the start of 2038. | ||||
.It | .It | ||||
▲ Show 20 Lines • Show All 617 Lines • Show Last 20 Lines |