1 \input texinfo @c -*-texinfo-*-
4 @settitle Sntp User's Manual
5 @include include/version.texi
10 This file documents the use of the NTP Project's SNTP, a program for
11 querying and setting the time.
15 * sntp: (sntp). Simple Network Time Protocol
19 @title Simple Network Time Protocol User's Manual
20 @subtitle sntp, version @value{VERSION}, @value{UPDATED}
21 @c @author Max @email{foo@ntp.org}
25 @c @vskip 0pt plus 1filll
27 @node Top, sntp Description, (dir), (dir)
28 @top Simple Network Time Protocol User Manual
30 This document describes the use of the NTP Project's @code{sntp} program,
31 that can be used to query a Network Time Protocol (NTP) server and
32 display the time offset of the system clock relative to the server
33 clock. Run as root, it can correct the system clock to this offset as
34 well. It can be run as an interactive command or from a cron job.
36 This document applies to version @value{VERSION} of @code{sntp}.
38 The program implements the SNTP protocol as defined by RFC 5905, the NTPv4
44 * sntp Description:: Description
45 * sntp Invocation:: Invoking sntp
49 @node sntp Description
50 @comment node-name, next, previous, up
53 By default, @code{sntp} writes the local data and time (i.e., not UTC) to the
54 standard output in the format:
57 1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs
61 YYYY-MM-DD HH:MM:SS.SUBSEC is the local date and time,
62 (+0800) is the local timezone adjustment (so we would add 8 hours and 0 minutes to convert the reported local time to UTC),
64 the +4.567 +/- 0.089 secs indicates the time offset and
65 error bound of the system clock relative to the server clock.
67 @include invoke-sntp.texi
70 @comment node-name, next, previous, up
73 The simplest use of this program is as an unprivileged command to
74 check the current time, offset, and error in the local clock.
78 sntp ntpserver.somewhere
81 With suitable privilege, it can be run as a command or in a
82 @code{crom} job to reset the local clock from a reliable server, like
83 the @code{ntpdate} and @code{rdate} commands.
87 sntp -a ntpserver.somewhere