RDATE

Section: LOCAL USER COMMANDS (8L)
Updated: 14 November 1990
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NAME

rdate - set the system date/time from a remote host

SYNOPSIS

rdate [ -adD ] host [ host ] ...

DESCRIPTION

rdate uses a specified remote host as a time server and resets the local system date/time to the value supplied by the remote host. One or more hosts can be specified on the command line. rdate will use the value from the first host which responds. Thus, the date/time can be reset even if the primary time server does not respond.

When a host has responded to the rdate request and the local date/time has been set, the name of the responding host and the time will be displayed on standard output.

rdate uses the TCP Time Protocol service specified in RFC868. This service provides the number of seconds since 00:00:00 1 January 1900 GMT on port 37. The returned value is corrected to the Unix epoch, 00:00:00 1 January 1970 GMT. Depending on the command line options, this value is used (1) to reset the local machine's date/time immediately to the new value, (2) to adjust the local machine's date/time gradually to the new value, or (3) for display only. The default is to reset the local date/time. Since the system calls used to modify the date/time are privileged, rdate must be run by root to successfully change the local date/time.

rdate is often used in a startup file such as /etc/rc.local to set the system date/time.

OPTIONS

-a: Use the server's time to gradually adjust the local date/time to the new value. This technique guarantees that there are no time discontinuities as the time is changed. (N.B.: The system call to gradually adjust time is not available on all versions of Unix and this option will not be provided on those systems.)
-d: Display the time from the first server to respond. Do not adjust or set the local machine's date/time.
-D: Display the time from all servers that respond. Do not adjust or set the local machine's date/time.

AUTHOR

Keith Pyle

DIAGNOSTICS

The exit status is 0 for mormal execution. If none of the specified hosts respond or if the time can not changed, the exit status is set to 1. Syntax errors result in a usage message and an exit status of 2.

This document was created by man2html, using the manual pages.
Time: 23:45:44 GMT, December 11, 2024