ntpclient.1

实现linux系统和网络时钟服务器的时间同步,从而可以得到准确的时间.

.\" man page for Larry Doolittle's ntpclient
.\" distributed under GPL
.\" originally written by Walter Harms
.TH ntpclient 3 "2005-28-07-05" "" "ntpclient"
.SH NAME
ntpclient \- client to get time from NTP server
.SH SYNOPSIS
.B ntpclient -h hostname [-c count] [-d] [-f frequency] [-g goodness]
.in 14
.B             [-i interval] [-l] [-p port] [-r] [-s]
.SH DESCRIPTION
.B ntpclient
is an NTP (RFC-1305) client for unix-alike computers.
Its functionality is a small subset of xntpd, but has the potential
to function better within
that limited scope.  Since it is much smaller than xntpd, it is
also more relevant for embedded computers.
.PP
Without any argument (except -h) the program produces output
similar to this:
.sp
.nf
 day   second     elapsed    stall     skew  dispersion  freq
36765 00180.386    1398.0     40.3  953773.9    793.5  -1240000
36765 00780.382    1358.0     41.3  954329.0    915.5  -1240000
36765 01380.381    1439.0     56.0  954871.3    915.5  -1240000
.fi
.sp
The columns have the following meaning:
.nf
day, second: time of measurement, UTC, relative to NTP epoch (Jan 1, 1900)
elapsed:     total time from query to response (microseconds)
stall:       time the server reports that it sat on the request (microseconds)
skew:        difference between local time and server time (microseconds)
dispersion:  reported by server, see RFC-1305 (microseconds)
freq:        local clock frequency adjustment (Linux only, ppm*65536)
.fi
.SS "Options"
.TP
.BI  -h " hostname"
(mandatory) NTP server, against which to measure system time
.TP
.BI -c " count"
top after count time measurements (default 0 means go forever)
.TP
.B  -d
.br
print diagnostics (feature can be disabled at compile time)
.TP
.BI  -g " goodness"
causes ntpclient to stop after getting a result more accurate
than goodness (microseconds, default 0 means go forever)
.TP
.BI  -i " interval"
check time every interval seconds (default 600)
.TP
.BI -p " port"
local NTP client UDP port (default 0 means "any available")
.TP
.BI  -q " min_delay"
minimum packet delay for transaction (default 800 microseconds)
.TP
.B  -r
.br
replay analysis code based on stdin (feature can be disabled at compile time)
.TP
.BI -f " frequency"
.br
initialize the frequency offset (Linux only, requires root access)
.TP
.B -s
.br
simple clock set (implies -c 1)
(requires root access)
.TP
.B  -l
.br
attempt to lock local clock to server using
.BR adjtimex (2)
(requires root access)
.TP
.B -t
.br
trust network and server, no RFC-4330 recommended cross-checks

.SH AUTHOR
 Larry Doolittle
 ntpclient home page: http://doolittle.icarus.com/ntpclient/
.SH COPYRIGHT
ntpclient is Copyright 1997, 1999, 2000, 2003, 2006, 2007 Larry Doolittle, and
may be freely copied and modified according to the terms of the GNU
General Public License, version 2.  If you want to distribute ntpclient
under other terms, contact me.  I might agree to some other arrangement,
if you talk to me
.I before
you start violating GPL terms.

.SH "SEE ALSO"
.BR adjtimex (2),
.BR www.ntp.org