68 lines
2.7 KiB
Groff
68 lines
2.7 KiB
Groff
.TH CHRONY 1 "August 10, 2001" chrony "User's Manual"
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.SH NAME
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chrony \- programs for keeping computer clocks accurate
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.SH SYNOPSIS
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\fBchronyc\fR [\fIOPTIONS\fR]
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\fBchronyd\fR [\fIOPTIONS\fR]
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.SH DESCRIPTION
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\fBchrony\fR is a pair of programs for keeping computer clocks accurate.
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\fIchronyd\fR is a background (daemon) program and \fIchronyc\fR is a
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command-line interface to it. Time reference sources for chronyd can be
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RFC1305 NTP servers, human (via keyboard and \fIchronyc\fR), or the computer's
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real-time clock at boot time (Linux only). chronyd can determine the rate at
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which the computer gains or loses time and compensate for it while no external
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reference is present. Its use of NTP servers can be switched on and off
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(through \fIchronyc\fR) to support computers with dial-up/intermittent access
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to the Internet, and it can also act as an RFC1305-compatible NTP server.
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.SH USAGE
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\fIchronyc\fR is a command-line interface program which can be used to
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monitor \fIchronyd\fR's performance and to change various operating
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parateters whilst it is running.
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\fIchronyd\fR's main function is to obtain measurements of the true (UTC)
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time from one of several sources, and correct the system clock
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accordingly. It also works out the rate at which the system clock
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gains or loses time and uses this information to keep it accurate
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between measurements from the reference.
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The reference time can be derived from either Network Time Protocol
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(NTP) servers (preferred), or wristwatch-and-keyboard (via \fIchronyc\fR).
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The main source of information about the Network Time Protocol is
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\fIhttp://www.eecis.udel.edu/~ntp\fR.
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It is designed so that it can work on computers which only have
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intermittent access to reference sources, for example computers which
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use a dial-up account to access the Internet. Of course, it will work
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on computers with permanent connections too.
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In addition, for Linux 2.0.x (for x >= 32) or 2.2 onwards, chronyd can monitor
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the system's real time clock performance, so the system can maintain accurate
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time even across reboots.
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Typical accuracies available between 2 machines are
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On an ethernet LAN : 100-200 microseconds, often much better
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On a V32bis dial-up modem connection : 10's of milliseconds (from one
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session to the next)
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\fIchronyd\fR can also operate as an RFC1305-compatible NTP server and peer.
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.SH "SEE ALSO"
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.BR chronyc(1),
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.BR chrony(1)
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.I http://chrony.sunsite.dk/
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.SH AUTHOR
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Richard Curnow <rc@rc0.org.uk>
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This man-page was written by Jan Schaumann <jschauma@netmeister.org> as part
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of "The Missing Man Pages Project". Please see
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\fIhttp://www.netmeister.org/misc/m2p2/index.html\fR for details.
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The complete chrony documentation is supplied in texinfo format.
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