xref: /netbsd-src/lib/libc/time/zdump.8 (revision a4ddc2c8fb9af816efe3b1c375a5530aef0e89e9)
1.\"	$NetBSD: zdump.8,v 1.9 2012/08/09 12:38:26 christos Exp $
2.Dd October 29, 2003
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 \-version
11.Op Fl v
12.Op Fl c Ar [loyear,]highyear
13.Op Ar zonename ...
14.Sh DESCRIPTION
15.Nm
16prints the current time in each
17.Ar zonename
18named on the command line.
19.Pp
20These options are available:
21.Bl -tag -width XXXXXXXXX -compact
22.It Fl \-version
23Output version information and exit.
24.It Fl v
25For each
26.Ar zonename
27on the command line,
28print the time at the lowest possible time value,
29the time one day after the lowest possible time value,
30the times both one second before and exactly at
31each detected time discontinuity,
32the time at one day less than the highest possible time value,
33and the time at the highest possible time value,
34Each line ends with
35.Dl isdst=1
36if the given time is Daylight Saving Time or
37.Dl isdst=0
38otherwise.
39.It Fl c Ar [loyear,]highyear
40Cut off the verbose output near the start of the given year(s).
41By default,
42the program cuts off verbose output near the starts of the years -500 and 2500.
43.El
44.Sh LIMITATIONS
45The
46.Fl v
47option may not be used on systems with floating-point time_t values
48that are neither float nor double.
49.Pp
50Time discontinuities are found by sampling the results returned by localtime
51at twelve-hour intervals.
52This works in all real-world cases;
53one can construct artificial time zones for which this fails.
54.Sh SEE ALSO
55.Xr ctime 3 ,
56.Xr tzfile 5 ,
57.Xr zic 8
58.\" @(#)zdump.8	8.2
59.\" This file is in the public domain, so clarified as of
60.\" 2009-05-17 by Arthur David Olson.
61