#hwclock

針對 Ubuntu 16.04 + PPPoE 時，OpenNTPD 的 -s 不會在啟動時直接校正的問題 workaround…

發現機器時間跟標準時間差了 40 秒左右，結果有些服務因為會看雙方時間，就不讓我跑… XDDD 找問題找了半天，發現開機後 ntpdate 會回報找不到伺服器，看起來是網路根本就還沒通就跑起來了： Jan 25 13:10:30 home ntpdate[757]: name server cannot be used: Temporary failure in name resolution (-3) Jan 25 13:10:30 home ntpdate[1171]: name server cannot be used: Temporary failure in name resolution (-3) Jan 25 13:10:30 home ntpdate[1347]: name server cannot be used: Temporary failure in name…

ネットが切れてるときでも時刻が必要になった。RPiにはRTCが無いのでボタン電池を電源にしたRX-8564をI2Cに繋いだ。でもRTCが動作しない...何故だろう？

I want to get the time, even if a net is not connected. RPi does not have RTC. I installed the RX-8564LC, the power supply is Li-battery CR2025, on the I2C bus.

But the RTC could not work... Why?

暫定対策案が記載されていました。↓ Thank you! http://sp-lab.extrem.ne.jp/archives/4008

こんな感じ

# hwclock -r

hwclock: select() to /dev/rtc0 to wait for clock tick timed out: No such file or directory

<One of factor was the bug of 'hwclock'. How to fix...> 実はhwclockのバグが要因の一つでした。hwclockをmakeし直します。

# wget https://www.kernel.org/pub/linux/utils/util-linux/v2.26/util-linux-2.26.1.tar.gz

#  tar zxvf util-linux-2.26.1.tar.gz

# cd util-linux-2.26.1

#  ./configure --without-python --without-systemd --without-ncurses  > /dev/null

# apt-get install gcc

# make hwclock

# cp hwclock /sbin/.

<add '/etc/rc.local'> 設定ファイル1rc.localを編集します。

So recently I was plagued with a frustrating issue where the system clock of a virtual machine would only ever be correct after syncing with NTP, After a reboot the system would go back to being 12 hours behind, regardless of the UTC setting, Here is how I fixed it.

Note: All machines in this post are running CentOS 6.4

First step was to check UTC was actually set, which required UTC=true to be present in /etc/sysconfig/clock

Now, after much googling, the /etc/adjtime file can cause all sorts of havoc if incorrectly set up.

So we delete it and regenerate it.

rm -f /etc/adjtime ; hwclock --systohc --utc -D

What this command does is deletes the adjtime file, then sets the hardware clock to the system clock, adjusting for UTC, this hwclock command will also regenerate the adjtime file correctly.

After which we reboot, sync with NTP to make sure our time is spot on, and that's that!