xref: /netbsd-src/lib/libc/time/zdump.8 (revision b1c86f5f087524e68db12794ee9c3e3da1ab17a0)
1.\"	$NetBSD: zdump.8,v 1.8 2010/01/08 23:14:13 joerg Exp $
2.\" @(#)zdump.8	7.4
3.Dd October 29, 2003
4.Dt ZDUMP 8
5.Os
6.Sh NAME
7.Nm zdump
8.Nd time zone dumper
9.Sh SYNOPSIS
10.Nm zdump
11.Op Fl \-version
12.Op Fl v
13.Op Fl c Ar [loyear,]highyear
14.Op Ar zonename ...
15.Sh DESCRIPTION
16.Nm
17prints the current time in each
18.Ar zonename
19named on the command line.
20.Pp
21These options are available:
22.Bl -tag -width XXXXXXXXX -compact
23.It Fl \-version
24Output version information and exit.
25.It Fl v
26For each
27.Ar zonename
28on the command line,
29print the time at the lowest possible time value,
30the time one day after the lowest possible time value,
31the times both one second before and exactly at
32each detected time discontinuity,
33the time at one day less than the highest possible time value,
34and the time at the highest possible time value,
35Each line ends with
36.Dl isdst=1
37if the given time is Daylight Saving Time or
38.Dl isdst=0
39otherwise.
40.It Fl c Ar [loyear,]highyear
41Cut off the verbose output near the start of the given year(s).
42By default,
43the program cuts off verbose output near the starts of the years -500 and 2500.
44.El
45.Sh LIMITATIONS
46The
47.Fl v
48option may not be used on systems with floating-point time_t values
49that are neither float nor double.
50.Pp
51Time discontinuities are found by sampling the results returned by localtime
52at twelve-hour intervals.
53This works in all real-world cases;
54one can construct artificial time zones for which this fails.
55.Sh SEE ALSO
56.Xr ctime 3 ,
57.Xr tzfile 5 ,
58.Xr zic 8
59.\" @(#)zdump.8	8.2
60.\" This file is in the public domain, so clarified as of
61.\" 2009-05-17 by Arthur David Olson.
62