xref: /openbsd-src/usr.sbin/zdump/zdump.8 (revision d32639f6ddc06f615d8e07a47d97091b3531a48f)
1.\"	$OpenBSD: zdump.8,v 1.3 2022/09/11 06:38:12 jmc Exp $
2.Dd $Mdocdate: September 11 2022 $
3.Dt ZDUMP 8
4.Os
5.Sh NAME
6.Nm zdump
7.Nd time zone dumper
8.Sh SYNOPSIS
9.Nm zdump
10.Op Fl v
11.Oo
12.Fl c
13.Oo Ar loyear , Oc Ar hiyear
14.Oc
15.Ar zonename ...
16.Sh DESCRIPTION
17.Nm
18prints the current time in each
19.Ar zonename
20named on the command line.
21.Pp
22These options are available:
23.Bl -tag -width Ds
24.It Xo
25.Fl c
26.Oo Ar loyear , Oc Ar hiyear
27.Xc
28Cut off verbose output near the start of the given year(s).
29By default,
30the program cuts off verbose output near the start of the years -500 and 2500.
31.It Fl v
32For each
33.Ar zonename
34on the command line,
35print the time at the lowest possible time value,
36the time one day after the lowest possible time value,
37the times both one second before and exactly at
38each detected time discontinuity,
39the time at one day less than the highest possible time value,
40and the time at the highest possible time value.
41Each line ends with
42.Dq isdst=1
43if the given time is Daylight Saving Time or
44.Dq isdst=0
45otherwise.
46.El
47.Sh LIMITATIONS
48The
49.Fl v
50option may not be used on systems with floating-point
51.Vt time_t
52values that are neither float nor double.
53.Pp
54Time discontinuities are found by sampling the results returned by localtime
55at twelve-hour intervals.
56This works in all real-world cases;
57.\" @(#)zdump.8	8.1
58.Sh SEE ALSO
59.Xr ctime 3 ,
60.Xr tzfile 5 ,
61.Xr zic 8
62.\" This file is in the public domain, so clarified as of
63.\" 2009-05-17 by Arthur David Olson.
64