FreeBSD: how to syncronize the system clock with the hardware clock in bash?
Solution 1
Check sysctl machdep.disable_rtc_set
. It should be 0
, and hardware clock is set automatically every time settimeofday()
is called. Then, if the ntpd
is running, you don't have to set hardware clock with a separate command as ntpd
already invokes this system call.
Solution 2
See answer 1 (below?) for general advice.
In order to make sure that ntpd will set the clock it should be run with the -g switch. Or if you do it by hand "ntpd -g -n". The last switch is to make sure that it does not fork. The first sets the time regardless. Watch the messages and exit using ^C. If it does not work, try using it with two -g switches.
Turn on ntp by enabling it in /etc/rc.conf There should be something like the following if ntpd is enabled. ntpd_enable="YES" ntpd_flags="-p /var/run/ntpd.pid -f /var/db/ntpd.drift -g -g"
Start the service with the command service ntpd start
openntpd sets the time when it starts so it seems to not need the -g option.
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Lilás
Updated on September 18, 2022Comments
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Lilás almost 2 years
I am writing a script that synchronizes the system clock with the hardware clock (aka RTC, or CMOS clock) assuming that no Network Time Protocol (NTP) daemon is running.
I am running in a virtual machine and the supervisor doesn't let the hardware clock to be changed by the guest.
So in linux, I can use the
hwclock --hctosys
to do this, in Debian for example:$ date Thu May 18 00:48:57 UTC 2017 $ date 0401121621 Thu Apr 1 12:16:00 UTC 2021 $ hwclock --hctosys # this set my system clock to the hardware clock back again $ date Thu May 18 00:49:28 UTC 2017
But how can I do the same thing on FreeBSD as it doesn't provide the hwclock utility? I tried using
adjkerntz -a
but it didn't work. I am running FreeBSD version 11.0-RELEASE-p9Thanks for your help
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Lilás about 7 yearsThanks for your reply but I want to set the clock the other way around, I don't want to change the hardware clock, I want to change the system clock
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Esa Jokinen about 7 yearsWhy? Your hardware clock is more reliable than NTP? Is your FreeBSD running on an atomic clock, keeping the whole Internet on correct time? :)