79 \fBntpdate\fR 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 \fBntpdate\fR from a \fBcron\fR script. However, it is important to note that \fBntpdate\fR with contrived \fBcron\fR scripts is no substitute for the NTP daemon, which uses sophisticated algorithms to maximize accuracy and reliability while minimizing resource use. Finally, since \fBntpdate\fR does not discipline the host clock frequency as does \fBntpd\fR, the accuracy using \fBntpdate\fR is limited. |
79 \fBntpdate\fR 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 \fBntpdate\fR from a \fBcron\fR script. However, it is important to note that \fBntpdate\fR with contrived \fBcron\fR scripts is no substitute for the NTP daemon, which uses sophisticated algorithms to maximize accuracy and reliability while minimizing resource use. Finally, since \fBntpdate\fR does not discipline the host clock frequency as does \fBntpd\fR, the accuracy using \fBntpdate\fR is limited. |
80 .LP |
80 .LP |
81 Time adjustments are made by \fBntpdate\fR in one of two ways. If \fBntpdate\fR determines the clock is in error more than 0.5 second it will simply step the time by calling the system \fBsettimeofday()\fR routine. If the error is less than 0.5 seconds, it will slew the time by calling the system \fBadjtime()\fR routine. The latter technique is less disruptive and more accurate when the error is small, and works quite well when \fBntpdate\fR is run by \fBcron\fR every hour or two. |
81 Time adjustments are made by \fBntpdate\fR in one of two ways. If \fBntpdate\fR determines the clock is in error more than 0.5 second it will simply step the time by calling the system \fBsettimeofday()\fR routine. If the error is less than 0.5 seconds, it will slew the time by calling the system \fBadjtime()\fR routine. The latter technique is less disruptive and more accurate when the error is small, and works quite well when \fBntpdate\fR is run by \fBcron\fR every hour or two. |
82 \fBntpdate\fR will decline to set the date if an NTP server daemon (e.g., \fBntpd\fR) is running on the same host. When running \fBntpdate\fR on a regular basis from \fBcron\fR 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. |
82 \fBntpdate\fR will decline to set the date if an NTP server daemon (e.g., \fBntpd\fR) is running on the same host. When running \fBntpdate\fR on a regular basis from \fBcron\fR 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. |
83 Note that in contexts where a host name is expected, a \fB-4\fR qualifier preceding the host name forces DNS resolution to the IPv4 namespace, while a \fB-6\fR qualifier forces DNS resolution to the IPv6 namespace. |
83 Note that in contexts where a host name is expected, a \fB-4\fR qualifier preceding the host name forces DNS resolution to the IPv4 namespace, while a \fB-6\fR qualifier forces DNS resolution to the IPv6 namespace. |
84 .SH ATTRIBUTES |
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85 See |
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86 .BR attributes (5) |
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87 for descriptions of the following attributes: |
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88 .sp |
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89 .TS |
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90 box; |
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91 cbp-1 | cbp-1 |
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92 l | l . |
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93 ATTRIBUTE TYPE ATTRIBUTE VALUE |
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94 = |
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95 Availability service/network/ntp |
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96 = |
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97 Interface Stability Uncommitted Obsolete |
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98 .TE |
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99 .PP |
84 .PP |
100 .SH NOTES |
85 .SH NOTES |
101 Source for ntpdate is available on http://src.opensolaris.org. |
86 Source for ntpdate is available on http://src.opensolaris.org. |
102 .LP |
87 .LP |
103 Disclaimer: The functionality of this program is now available in the \fBntpd\fB program. See the \fB-q\fB command line option in the \fBntpd\fB - Network Time Protocol (NTP) daemon man page. After a suitable period, the \fBntpdate\fB program is to be retired from this distribution |
88 Disclaimer: The functionality of this program is now available in the \fBntpd\fB program. See the \fB-q\fB command line option in the \fBntpd\fB - Network Time Protocol (NTP) daemon man page. After a suitable period, the \fBntpdate\fB program is to be retired from this distribution |