1\input texinfo @c -*-texinfo-*- 2@c %**start of header 3@setfilename sntp.info 4@settitle Sntp User's Manual 5@include include/version.texi 6@paragraphindent 2 7@c %**end of header 8 9@ifinfo 10This file documents the use of the NTP Project's SNTP, a program for 11querying and setting the time. 12@end ifinfo 13 14@direntry 15* sntp: (sntp). Simple Network Time Protocol 16@end direntry 17 18@titlepage 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} 22@end titlepage 23 24@c @page 25@c @vskip 0pt plus 1filll 26 27@node Top, sntp Description, (dir), (dir) 28@top Simple Network Time Protocol User Manual 29 30This document describes the use of the NTP Project's @code{sntp} program, 31that can be used to query a Network Time Protocol (NTP) server and 32display the time offset of the system clock relative to the server 33clock. Run as root, it can correct the system clock to this offset as 34well. It can be run as an interactive command or from a cron job. 35 36This document applies to version @value{VERSION} of @code{sntp}. 37 38The program implements the SNTP protocol as defined by RFC 5905, the NTPv4 39IETF specification. 40 41@shortcontents 42 43@menu 44* sntp Description:: Description 45* sntp Invocation:: Invoking sntp 46* Usage:: Usage 47@end menu 48 49@node sntp Description 50@comment node-name, next, previous, up 51@section Description 52 53By default, @code{sntp} writes the local data and time (i.e., not UTC) to the 54standard output in the format: 55 56@example 571996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs 58@end example 59 60where 61YYYY-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), 63and 64the +4.567 +/- 0.089 secs indicates the time offset and 65error bound of the system clock relative to the server clock. 66 67@include invoke-sntp.texi 68 69@node Usage 70@comment node-name, next, previous, up 71@section Usage 72 73The simplest use of this program is as an unprivileged command to 74check the current time, offset, and error in the local clock. 75For example: 76 77@example 78sntp ntpserver.somewhere 79@end example 80 81With 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 83the @code{ntpdate} and @code{rdate} commands. 84For example: 85 86@example 87sntp -a ntpserver.somewhere 88@end example 89