ntpdate
(1m)
名前
ntpdate - set the date and time with NTP
形式
/usr/sbin/ntpdate [-46bBdqsuv] [-a key] [-e Authdelay] [-k
keyfile] [-o version] [-p samples] [-t timeout] server [ ...
]
説明
SunOS 5.11 1
System Administration Commands ntpdate(1M)
NAME
ntpdate - set the date and time with NTP
SYNOPSIS
/usr/sbin/ntpdate [-46bBdqsuv] [-a key] [-e Authdelay] [-k
keyfile] [-o version] [-p samples] [-t timeout] server [ ...
]
OPTIONS
-4 Force DNS resolution of following host names on the
command line to the IPv4 namespace.
-6 Force DNS resolution of following host names on the
command line to the IPv6 namespace.
-a key
Enable authentication and specify the key identifier to
be used for authentication as the argument key. The
keys and key identifiers must match in both the client
and server key files. The default is to disable authen-
tication.
-B Force the time to always be slewed using the adjtime()
system call, even if the measured offset is greater
than 0.5 seconds. The default is to step the time using
settimeofday() if the offset is greater than +-0.5s.
Note that, if the offset is much greater than +-0.5s in
this case, that it can take a long time (hours) to slew
the clock to the correct value. During this time, the
host should not be used to synchronize clients.
-b Force the time to be stepped using the settimeofday()
system call, rather than slewed (default) using the
adjtime() system call. This option should be used when
called from a startup file at boot time.
-d Enable the debugging mode, in which ntpdate will go
through all the steps, but not adjust the local clock.
Information useful for general debugging will also be
printed.
-e authdelay
Specify the processing delay to perform an authentica-
tion function as the value authdelay, in seconds and
fraction (see ntpd for details). This number is usually
small enough to be negligible for most purposes, though
specifying a value may improve timekeeping on very slow
CPU's.
-k keyfile
Specify the path for the authentication key file as the
string keyfile. The default is /etc/inet/ntp.keys. This
SunOS 5.11 Last change: 1
System Administration Commands ntpdate(1M)
file should be in the format described in ntpd.
-o version
Specify the NTP version for outgoing packets as the
integer version, which can be 1 or 2. The default is 3.
This allows ntpdate to be used with older NTP versions.
-p samples
Specify the number of samples to be acquired from each
server as the integer samples, with values from 1 to 8
inclusive. The default is 4.
-q Query only - don't set the clock.
-s Divert logging output from the standard output
(default) to the system syslog facility.
-t timeout
Specify the maximum time waiting for a server response
as the value timeout, in seconds and fraction. The
value is is rounded to a multiple of 0.2 seconds. The
default is 1 second, a value suitable for polling
across a LAN.
-u Direct ntpdate to use an unprivileged port or outgoing
packets. This is most useful when behind a firewall
that blocks incoming traffic to privileged ports, and
you want to synchronise with hosts beyond the firewall.
Note that the -d option always uses unprivileged ports.
-v Print ntpdate's version identification string during
program startup.
DESCRIPTION
ntpdate sets the local date and time by polling the Network
Time Protocol (NTP) server(s) given as the server arguments
to determine the correct time. It must be run as root unless
the -d or -q options are used. A number of samples are
obtained from each of the servers specified and a subset of
the NTP clock filter and selection algorithms are applied to
select the best of these. Note that the accuracy and relia-
bility of ntpdate depends on the number of servers, the num-
ber of polls each time it is run and the interval between
runs.
ntpdate can be run manually as necessary to set the host
clock, or it can be run from the host startup script to set
the clock at boot time. It is also possible to run ntpdate
from a cron script. However, it is important to note that
ntpdate with contrived cron scripts is no substitute for the
NTP daemon, which uses sophisticated algorithms to maximize
accuracy and reliability while minimizing resource use.
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System Administration Commands ntpdate(1M)
Finally, since ntpdate does not discipline the host clock
frequency as does ntpd, the accuracy using ntpdate is lim-
ited.
Time adjustments are made by ntpdate in one of two ways. If
ntpdate determines the clock is in error more than 0.5 sec-
ond it will simply step the time by calling the system set-
timeofday() routine. If the error is less than 0.5 seconds,
it will slew the time by calling the system adjtime() rou-
tine. The latter technique is less disruptive and more accu-
rate when the error is small, and works quite well when ntp-
date is run by cron every hour or two. ntpdate will decline
to set the date if an NTP server daemon (e.g., ntpd) is run-
ning on the same host. When running ntpdate on a regular
basis from cron as an alternative to running a daemon, doing
so once every hour or two will result in precise enough
timekeeping to avoid stepping the clock. Note that in con-
texts where a host name is expected, a -4 qualifier preced-
ing the host name forces DNS resolution to the IPv4 names-
pace, while a -6 qualifier forces DNS resolution to the IPv6
namespace.
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
+---------------+----------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+----------------------+
|Availability | service/network/ntp |
+---------------+----------------------+
|Stability | Uncommitted obsolete |
+---------------+----------------------+
NOTES
Disclaimer: The functionality of this program is now avail-
able in the ntpd program. See the -q command line option in
the ntpd - Network Time Protocol (NTP) daemon man page. The
ntpdate program is to be retired from this distribution.
SEE ALSO
ntpd(1M), ntpdc(1M), attributes(5)
This software was built from source available at
https://java.net/projects/solaris-userland. The original
community source was downloaded from http://ar-
chive.ntp.org/ntp4/ntp-dev/ntp-dev-4.2.7p381.tar.gz
Further information about this software can be found on the
open source community website at http://www.ntp.org/.
SunOS 5.11 Last change: 3