1.\" $OpenBSD: rdate.8,v 1.35 2012/08/30 06:48:33 jmc Exp $ 2.\" $NetBSD: rdate.8,v 1.4 1996/04/08 20:55:17 jtc Exp $ 3.\" 4.\" Copyright (c) 1994 Christos Zoulas 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by Christos Zoulas. 18.\" 4. The name of the author may not be used to endorse or promote products 19.\" derived from this software without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31.\" 32.Dd $Mdocdate: August 30 2012 $ 33.Dt RDATE 8 34.Os 35.Sh NAME 36.Nm rdate 37.Nd set the system's date from a remote host 38.Sh SYNOPSIS 39.Nm rdate 40.Op Fl 46acnpsv 41.Ar host 42.Sh DESCRIPTION 43.Nm 44displays and sets the local date and time from the 45host name or address given as the argument. 46The time source may be an RFC 868 TCP protocol server, 47which is usually implemented as a built-in service of 48.Xr inetd 8 , 49or an RFC 5905 protocol SNTP/NTP server. 50By default, 51.Nm 52uses the RFC 868 TCP protocol. 53.Pp 54The options are as follows: 55.Bl -tag -width Ds 56.It Fl 4 57Forces 58.Nm 59to use IPv4 addresses only. 60.It Fl 6 61Forces 62.Nm 63to use IPv6 addresses only. 64.It Fl a 65Use the 66.Xr adjtime 2 67call to gradually skew the local time to the 68remote time rather than just hopping. 69.It Fl c 70Correct leap seconds. 71This should be used only when synchronizing to a server 72which does not correctly account for leap seconds. 73.It Fl n 74Use SNTP (RFC 5905) instead of the RFC 868 time protocol. 75.It Fl p 76Do not set, just print the remote time. 77.It Fl s 78Do not print the time. 79.It Fl v 80Verbose output. 81Always show the adjustment. 82.El 83.Sh FILES 84.Bl -tag -width /var/log/wtmp -compact 85.It Pa /var/log/wtmp 86record of date resets and time changes 87.El 88.Sh EXAMPLES 89To get the legal time in Germany, set the 90.Pa /etc/localtime 91symlink to 92.Pa /usr/share/zoneinfo/right/Europe/Berlin 93and issue the following command: 94.Pp 95.D1 Li "# rdate -nv ptbtime1.ptb.de" 96.Pp 97The command of course assumes you have a working internet connection 98and DNS set up to connect to the server at 99.Sy Physikalisch-Technische Bundesanstalt 100in Braunschweig, Germany. 101.Sh SEE ALSO 102.Xr date 1 , 103.Xr adjtime 2 , 104.Xr inetd 8 , 105.Xr ntpd 8 106