xref: /src/external/bsd/ntp/dist/ntpdc/ntpdc.texi

\input texinfo    @c -*-texinfo-*-
@c %**start of header
@setfilename ntpdc.info
@settitle ntpdc: NTPD Control User's Manual
@include ../sntp/include/version.texi
@paragraphindent 2
@c %**end of header

@ifinfo
This file documents the use of the NTP Project's ntpdc, a program for
controlling ntpd.
@end ifinfo

@direntry
* ntpdc: (ntpdc).                               ntpd Control program
@end direntry

@titlepage
@title ntpdc: NTPD Control User's Manual
@subtitle ntpdc, version @value{VERSION}, @value{UPDATED}
@c @author Max @email{foo (a] ntp.org}
@end titlepage

@c @page
@c @vskip 0pt plus 1filll

@node Top, ntpdc Description, (dir), (dir)
@top ntpdc: NTPD Control User Manual

This document describes the use of the NTP Project's @code{ntpdc} program,
that can be used to query a Network Time Protocol (NTP) server and
display the time offset of the system clock relative to the server
clock.  Run as root, it can correct the system clock to this offset as
well.  It can be run as an interactive command or from a cron job.

This document applies to version @value{VERSION} of @code{ntpdc}.

The program implements the SNTP protocol as defined by RFC 5905, the NTPv4
IETF specification.

@shortcontents

@menu
* ntpdc Description::            Description
* ntpdc Invocation::		Invoking ntpdc
* Usage::                       Usage
@end menu

@node ntpdc Description
@comment  node-name,  next,  previous,  up
@section Description

By default, @code{ntpdc} writes the local data and time (i.e., not UTC) to the
standard output in the format:

@example
1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs
@end example

where
YYYY-MM-DD HH:MM:SS.SUBSEC is the local date and time,
(+0800) is the local timezone adjustment (so we would add 8 hours and 0 minutes to convert the reported local time to UTC),
and
the +4.567 +/- 0.089 secs indicates the time offset and
error bound of the system clock relative to the server clock.

@include invoke-ntpdc.texi

@node Usage
@comment  node-name,  next,  previous,  up
@section Usage

The simplest use of this program is as an unprivileged command to
check the current time, offset, and error in the local clock.
For example:

@example
ntpdc ntpserver.somewhere
@end example

With suitable privilege, it can be run as a command or in a
@code{cron} job to reset the local clock from a reliable server, like
the @code{ntpdate} and @code{rdate} commands.
For example:

@example
ntpdc -a ntpserver.somewhere
@end example