126 lines
3.8 KiB
Groff
126 lines
3.8 KiB
Groff
.\" man page for Larry Doolittle's ntpclient
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.\" distributed under GPL
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.\" originally written by Walter Harms
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.Dd Aug 1, 2017
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.\" Please adjust this date whenever revising the manpage.
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.Dt NTPCLIENT 8
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.Sh NAME
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.Nm ntpclient
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.Nd Simple NTP client
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.Sh SYNOPSIS
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.Nm
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.Op Fl dhlLnrstvV
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.Op Fl c Ar count
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.Op Fl f Ar frequency
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.Op Fl g Ar goodness
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.Op Fl i Ar interval
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.Op Fl p Ar port
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.Op Fl q Ar min_delay
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.Op SERVER
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.Sh DESCRIPTION
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.Nm
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is an NTP (RFC-1305) client for UNIX-alike computers. Its functionality is a
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small subset of xntpd, but has the potential to function better within that
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limited scope. Since it is much smaller than xntpd, it is also more relevant
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for embedded computers.
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.Pp
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If run as root the program daemonizes itself by default and starts synchronizing
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with the given NTP server using default settings. When run as a regular user the
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program produces output similar to this:
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.Bd -unfilled -offset indent
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Day Second Elapsed Stall Skew Dispersion Freq
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36765 00180.386 1398.0 40.3 953773.9 793.5 -1240000
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36765 00780.382 1358.0 41.3 954329.0 915.5 -1240000
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36765 01380.381 1439.0 56.0 954871.3 915.5 -1240000
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.Ed
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.Pp
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The columns have the following meaning:
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.Pp
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.Bl -tag -width DaysSeconds -compact -offset indent
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.It Cm Day, Second
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Time of measurement, UTC, relative to NTP epoch (Jan 1, 1900)
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.It Cm Elapsed
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Total time from query to response (microseconds)
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.It Cm Stall
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Time the server reports that it sat on the request (microseconds)
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.It Cm Skew
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Difference between local time and server time (microseconds)
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.It Cm Dispersion
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Reported by server, see RFC-1305 (microseconds)
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.It Cm Freq
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Local clock frequency adjustment (Linux only, ppm*65536)
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.El
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.Sh OPTIONS
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Note, if the
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.Ar SERVER
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argument is omitted,
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.Nm
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defaults to use pool.ntp.org.
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.Bl -tag -width Ds
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.It Fl c Ar count
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Stop after count time measurements (default 0 means go forever)
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.It Fl d
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NTP debug/diagnostics, very noisy.
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.It Fl f Ar frequency
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Initialize the frequency offset. Linux only, requires root access.
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.It Fl g Ar goodness
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Stop
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.Nm
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after getting a result more accurate than goodness microseconds,
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default 0 means go forever.
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.It Fl h
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Show summary of command line options and exit.
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.It Fl i Ar interval
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Check time every interval seconds, default 600.
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.It Fl l
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Attempt to lock local clock to server using
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.Xr adjtimex 1 ,
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requires root access.
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.It Fl L
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Use syslog instead of stdout for log messages, default when started as
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root.
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.It Fl n
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Don't fork. Prevents ntpclient from daemonizing and also implies
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logging to stdout, use
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.Fl L
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to enable syslog in this mode.
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.It Fl p Ar port
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Local NTP client UDP port, default 0 means "any available". Very rarely
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necessary to change.
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.It Fl q Ar min_delay
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Minimum packet delay for transaction, default 800 microseconds.
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.It Fl r
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Replay analysis code based on stdin, feature is disabled by default
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compile time.
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.It Fl s
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Simple clock set, implies
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.Fl c Ar 1 ,
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requires root access.
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.It Fl t
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Trust network and server, no RFC-4330 recommended cross-checks.
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.It Fl v
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Verbose operation. This option will cause time sync events, and version
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information at start/stop to be logged.
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.It Fl V
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Display version and copyright information.
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.El
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.Sh AUTHORS
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Larry Doolittle maintains the original,
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.Lk http://doolittle.icarus.com/ntpclient/ upstream
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.Pp
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Joachim Nilsson maintains this at
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.Lk https://github.com/troglobit/ntpclient GitHub
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.Sh COPYRIGHT
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The
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.Nm
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package is Copyright 1997-2015 Larry Doolittle, and Copyright 2010-2018
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Joachim Nilsson. It can be freely copied, modified and used according
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to the terms of the GNU General Public License, version 2. If you want
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to distribute ntpclient under other terms, contact Larry. He might
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agree to other arrangements if you talk to him
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.Em before
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you start violating the terms of the license.
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.Sh "SEE ALSO"
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.Xr adjtimex 1 ,
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.Lk http://www.ntp.org
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