NAME¶
rdate —
set the system's date from a
remote host
SYNOPSIS¶
| rdate |
[-46acnpsuv]
[-o port]
host |
DESCRIPTION¶
rdate displays and sets the local date and time from the host
name or address given as the argument. The time source may be an RFC 868 TCP
protocol server, which is usually implemented as a built-in service of
inetd(8), or an RFC 2030 protocol SNTP/NTP server. By
default,
rdate uses the RFC 868 TCP protocol.
The options are as follows:
- -4
- Forces rdate to use IPv4 addresses
only.
- -6
- Forces rdate to use IPv6 addresses
only.
- -a
- Use the adjtime(2) call to gradually skew
the local time to the remote time rather than just hopping.
- -c
- Correct leap seconds. Sometimes required when synchronizing
to an NTP server. When synchronizing using the RFC 868 protocol, use this
option only if the server does not correctly account for leap seconds. You
can determine if you need this parameter if you sync against an NTP server
(with this parameter) or (recommended) check with a local radio controlled
watch or phone service.
- -n
- Use SNTP (RFC 2030) instead of the RFC 868 time
protocol.
- -o
port
- Use port port instead of port
37.
- -p
- Do not set, just print the remote time.
- -s
- Do not print the time.
- -u
- Use UDP instead of TCP as transport.
- -v
- Verbose output. Always show the adjustment.
FILES¶
- /var/log/wtmp
- record of date resets and time changes
EXAMPLES¶
To get the legal time in Germany, set the
/etc/localtime
symlink to
/usr/share/zoneinfo/right/Europe/Berlin and issue
the following command:
# rdate -ncv ptbtime1.ptb.de
The command of course assumes you have a working internet connection and DNS set
up to connect to the server at
Physikalisch-Technische
Bundesanstalt in Braunschweig, Germany.
To gradually adjust time once an hour after the first “step”
adjustment, put the following line into root's crontab:
58 * * * * rdate -ncav ptbtime1.ptb.de | logger
-t NTP
To to set the time through an ssh tunnel, use something like so:
ssh -f -L 10037:time.example.com:37
tyr.example.com sleep 10
rdate -a -o 10037 locahost
SEE ALSO¶
date(1),
adjtime(2),
inetd(8),
ntpd(8),
timed(8)
AUTHORS¶
This manual page was written by
Christos Zoulas. It was
changed by
Anibal Monsalve Salazar for the Debian Project.
