1.\" $NetBSD: zdump.8,v 1.14 2014/10/23 18:45:58 christos Exp $ 2.Dd October 23, 2014 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 V 13.Op Fl c Ar [loyear,]highyear 14.Op Ar zonename ... 15.Nm zdump 16.Fl t 17.Ar [lotime,]hightime 18.Op Ar zonename ... 19.Sh DESCRIPTION 20.Nm 21prints the current time in each 22.Ar zonename 23named on the command line. 24.Pp 25These options are available: 26.Bl -tag -width XXXXXXXXX -compact 27.It Fl \-version 28Output version information and exit. 29.It Fl v 30For each 31.Ar zonename 32on the command line, 33print the time at the lowest possible time value, 34the time one day after the lowest possible time value, 35the times both one second before and exactly at 36each detected time discontinuity, 37the time at one day less than the highest possible time value, 38and the time at the highest possible time value. 39Each line is followed by 40.Dl isdst= D 41where 42.Dl D 43is positive, zero, or negative depending on whether 44the given time is daylight saving time, standard time, 45or an unknown time type, respectively. 46Each line is also followed by 47.Dl gmtoff= N 48if the given local time is known to be 49.D N 50seconds east of Greenwich. 51.It Fl c Ar [loyear,]highyear 52Cut off verbose output at the given year(s). 53Cutoff times are computed using the proleptic Gregorian calendar with year 0 54and with Universal Time (UT) ignoring leap seconds. 55The lower bound is exclusive and the upper is inclusive; for example, a 56.Dl loyear 57of 1970 excludes a transition occurring at 1970-01-01 00:00:00 UTC but a 58.Dl hiyear 59of 1970 includes the transition. 60The default cutoff is 61.Dl \*-500,2500 . 62.It Fl t Ar [lotime,]hightime 63Cut off verbose output at the given time(s), 64given in decimal seconds since 1970-01-01 00:00:00 65Coordinated Universal Time (UTC). 66The 67.Ar zonename 68determines whether the count includes leap seconds. 69As with 70.Fl c , 71the cutoff's lower bound is exclusive and its upper bound is inclusive. 72.It Fl V 73Like 74.Fl v , 75except omit the times relative to the extreme time values. 76This generates output that is easier to compare to that of 77implementations with different time representations. 78.El 79.Sh LIMITATIONS 80Time discontinuities are found by sampling the results returned by localtime 81at twelve-hour intervals. 82This works in all real-world cases; 83one can construct artificial time zones for which this fails. 84.Pp 85In the output, 86.Dq UT 87denotes the value returned by 88.Xr gmtime 3 , 89which uses UTC for modern time stamps and some other UT flavor for 90time stamps that predate the introduction of UTC. 91No attempt is currently made to have the output use 92.Dq UTC 93for newer and 94.Dq UT 95for older time stamps, 96partly because the exact date of the introduction of UTC is problematic. 97.Sh SEE ALSO 98.Xr ctime 3 , 99.Xr tzfile 5 , 100.Xr zic 8 101.\" @(#)zdump.8 8.2 102.\" This file is in the public domain, so clarified as of 103.\" 2009-05-17 by Arthur David Olson. 104