# Manually Setting the System Clock **URL:** \ **Category:** Product support\ **Tags:** time\ **Created:** [April 13, 2020, 3:45pm UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319 "2020-04-13T15:45:58Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![AdamLee](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/adamlee/32/2149_2.png) [@AdamLee](https://forums.balena.io/u/AdamLee)\ **Post date:** [April 13, 2020, 3:45pm UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319/1 "2020-04-13T15:45:58Z")
On one of our devices we are allowing users to manually adjust the system time. This is because we expect that a majority of the time we wonn’t have internet connectivity. What we did was implement an endpoint in one of our existing containers that set the system clock based on the time it receives. It uses the [this node library](https://github.com/ConnorChristie/Set-System-Clock). It works just fine to set the time and I can see the time reflected in the containers and in the host OS by using the date command. The logs also output updated timestamps as I would expect. The issue is when the device is rebooted the time is different. For example, on my host OS after changing the time it shows: ``` ~# date Mon Apr 13 10:41:35 UTC 2020 ``` Now when I reboot I get: ``` ~# date Mon Apr 13 15:44:31 UTC 2020 ``` It should be noted that I’m currently in CST (UTC -5:00). Does anyone know what’s happening here? ---
**Author:** ![alanb128](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/alanb128/32/2839_2.png) [@alanb128](https://forums.balena.io/u/alanb128)\ **Post date:** [April 13, 2020, 4:53pm UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319/3 "2020-04-13T16:53:54Z")
Hello @AdamLee, Can you provide the version of balenaOS your device is running? The time management works a little differently on older versions so I want to make sure we are looking at the correct services. ---
**Author:** ![AdamLee](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/adamlee/32/2149_2.png) [@AdamLee](https://forums.balena.io/u/AdamLee)\ **Post date:** [April 13, 2020, 4:55pm UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319/4 "2020-04-13T16:55:34Z")
Host OS Version: [balenaOS 2.47.0+rev1](https://github.com/balena-os/meta-balena/blob/master/CHANGELOG.md) Supervisor Version: [10.6.27](https://github.com/balena-io/balena-supervisor/blob/master/CHANGELOG.md#v10627) ---
**Author:** ![alanb128](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/alanb128/32/2839_2.png) [@alanb128](https://forums.balena.io/u/alanb128)\ **Post date:** [April 13, 2020, 5:24pm UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319/5 "2020-04-13T17:24:29Z")
Thanks for that information. When you reboot the device it will initially poll the NTP sources and use that time if it reaches them. (More information about that here: [https://www.balena.io/docs/reference/OS/time/#chrony](https://www.balena.io/docs/reference/OS/time/#chrony) ) So if you are setting the time to something other than the current UTC and then rebooting, your example appears to be the expected behavior. ---
**Author:** ![AdamLee](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/adamlee/32/2149_2.png) [@AdamLee](https://forums.balena.io/u/AdamLee)\ **Post date:** [April 16, 2020, 4:24pm UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319/7 "2020-04-16T16:24:55Z")
Thanks - I read the time management docs, very useful information. Is there any way to turn of NTP polling, by chance? Like let’s say if I wanted to turn this thing into a wrist watch with a RTC. ---
**Author:** ![ab77](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/ab77/32/2870_2.png) [@ab77](https://forums.balena.io/u/ab77)\ **Post date:** [April 16, 2020, 4:44pm UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319/8 "2020-04-16T16:44:44Z")
Hi there, `chrony` does have RTC support, but since most hardware (RPi) doesn’t have one on-board by default, you would need to add a RTC hardware module (via GPIO) first and configure `chrony` to use it. This is documented in the `chrony` [docs](https://chrony.tuxfamily.org/faq.html#_i_want_to_use_code_chronyd_code_s_rtc_support_must_i_disable_code_hwclock_code). ---
**Author:** ![AdamLee](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/adamlee/32/2149_2.png) [@AdamLee](https://forums.balena.io/u/AdamLee)\ **Post date:** [April 16, 2020, 10:08pm UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319/10 "2020-04-16T22:08:42Z")
I’ve got an RTC hooked up and added the overlay parameters. How do I change the chrony configuration file? I tried doing it from the host OS but it complained that it was read only. I can’t see it in the SD card (using Windows). I’m a super Linux noob. ---
**Author:** ![rahul-thakoor](https://avatars.discourse-cdn.com/v4/letter/r/9de053/32.png) [@rahul-thakoor](https://forums.balena.io/u/rahul-thakoor)\ **Post date:** [April 17, 2020, 11:13am UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319/14 "2020-04-17T11:13:13Z")
Hey @AdamLee, balenaOS is already configured to use RTC, you can check the default set [here](https://github.com/balena-os/meta-balena/blob/master/meta-balena-common/recipes-core/chrony/files/chrony.conf#L11). It is using `rtcsync`. If I understand correctly, you need to disable the `chrony` service in the hostOS which will prevent NTP from updating the time. Here is how you could proceed: Use a container with `dbus-send` and execute the following command: `DBUS_SYSTEM_BUS_ADDRESS=unix:path=/host/run/dbus/system_bus_socket dbus-send --system --dest=org.freedesktop.systemd1 --type=method_call --print-reply /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager.StopUnit string:"chronyd.service" string:"replace"` For this to work, you will need to set ```auto labels: io.balena.features.dbus: '1' ``` for your service. You can refer to [the documentation on how to communicate with the hostOS from a container using `dbus`](https://www.balena.io/docs/learn/develop/runtime/#dbus-communication-with-host-os). Hope this is helpful. Let us know how it goes. Thanks ---
**Author:** ![AdamLee](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/adamlee/32/2149_2.png) [@AdamLee](https://forums.balena.io/u/AdamLee)\ **Post date:** [April 17, 2020, 3:49pm UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319/16 "2020-04-17T15:49:13Z")
This did not seem to work. I must admit it took a little bit to get it to function because I fell into this pitfall: > [@Dbus: Failed to connect to socket /host/run/dbus/system](https://forums.balena.io/t/dbus-failed-to-connect-to-socket-host-run-dbus-system/3107/9): > > You are using the dbus-send command inside the Dockerfile. Instead of invoking it during build time, you need to do that in runtime from your start.sh script. This is the reply from the dbus-send command: ``` 17.04.20 09:58:00 (+0000) api method return time=1587117480.786902 sender=:1.1 -> destination=:1.6250 serial=177495 reply_serial=2 17.04.20 09:58:00 (+0000) api object path "/org/freedesktop/systemd1/job/79940" ``` When I changed the system time on the device, disconnected from the network, and power cycled it came up with a completely incorrect time. I thought originally that I would have to change the rtcsync directive in chrony to rtcfile, which is why I had originally asked how to edit that configuration: > The `hwclock` program is often set-up by default in the boot and shutdown scripts with many Linux installations. With the kernel RTC synchronisation ( `rtcsync` directive), the RTC will be set also every 11 minutes as long as the system clock is synchronised. **If you want to use `chronyd` 's RTC monitoring ( `rtcfile` directive), it’s important to disable `hwclock` in the shutdown procedure. If you don’t, it will over-write the RTC with a new value, unknown to `chronyd` . At the next reboot, `chronyd` started with the `-s` option will compensate this (wrong) time with its estimate of how far the RTC has drifted whilst the power was off, giving a meaningless initial system time.** > > There is no need to remove `hwclock` from the boot process, as long as `chronyd` is started after it has run. > > [chrony – Frequently Asked Questions](https://chrony.tuxfamily.org/faq.html#_i_want_to_use_code_chronyd_code_s_rtc_support_must_i_disable_code_hwclock_code) After reconnecting to the network, and then power cycling again it’s clear that NTP was used because the system time now reflects the current UTC time. ---
**Author:** ![AdamLee](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/adamlee/32/2149_2.png) [@AdamLee](https://forums.balena.io/u/AdamLee)\ **Post date:** [April 23, 2020, 8:23pm UTC](https://forums.balena.io/t/manually-setting-the-system-clock/93319/17 "2020-04-23T20:23:41Z")
My guess after reading some docs is that command is happening after the clock is already synchronized with NTP.