- "Network Time Protocol daemon"
] [ -f file
] [ -p file
daemon synchronizes the local clock to one or more remote NTP
servers or local timedelta sensors. ntpd
can also act as an NTP server
itself, redistributing the local time. It implements the Simple Network Time
Protocol version 4, as described in RFC 2030, and the Network Time Protocol
version 3, as described in RFC 1305.
uses the adjtime(2)
system call to correct the local system
time without causing time jumps. Adjustments larger than 128ms are logged
with LOG_INFO priority. The threshold value is chosen
to avoid having local clock drift thrash the log files. Should ntpd
started with the -d
option, all calls to adjtime(2)
starts up, it reads settings from a configuration file,
The options are as follows:
- Do not daemonize. If this option is specified, ntpd will run in the
foreground and log to stderr.
- -p file
- Write pid to file
- -f file
- Use file as the configuration file, instead of the default
- Configtest mode. Only check the configuration file for validity.
- Do not set the time immediately at startup. This is the default.
- Set the time immediately at startup if the local clock is off by more than
180 seconds. Allows for a large time correction, eliminating the need to
run rdate(8) before starting .
- This option allows ntpd to send DEBUG priority messages to syslog.
When ntpd receives a SIGUSR1 signal, it will write its peer
and sensor status to syslog.
- default ntpd configuration file
- drift file, written by ntpd periodically and used at startup to get
the initial clock drift
, Network Time Protocol (Version 3)
, March 1992.
, Simple Network Time Protocol (SNTP) Version 4
, October 1996.
program first appeared in OpenBSD 3.6 .