Packages and Binaries:
Some machines don’t have a working realtime clock (RTC) unit, or no driver for the hardware that does exist. fake-hwclock is a simple set of scripts to save the kernel’s current clock periodically (including at shutdown) and restore it at boot so that the system clock keeps at least close to realtime. This will stop some of the problems that may be caused by a system believing it has travelled in time back to 1970, such as needing to perform filesystem checks at every boot.
On top of this, use of NTP is still recommended to deal with the fake clock “drifting” while the hardware is halted or rebooting.
How to install:
sudo apt install fake-hwclock
Control fake hardware clock
[email protected]:~# man fake-hwclock FAKE-HWCLOCK(8) System Manager's Manual FAKE-HWCLOCK(8) NAME fake-hwclock - Control fake hardware clock SYNOPSIS fake-hwclock [ command ] [ force ] BACKGROUND Many embedded Linux systems do not have a functional hardware clock. Either they simply don't have a hardware clock at all or they have a hardware clock but it is not usable (e.g. because Linux doesn't know how to use it or because no battery is present). This can lead to time moving backwards to some default value (often 1970) when the system is rebooted. Since lots of software assumes that time only moves forward this is a bad thing. NTP can (and should where practical) be used to sync with an external timeserver but it is not available early in the boot process and may be unavailable for other reasons. The design expectation of fake-hwclock is that it will be run very late at shutdown and very early at boot. This will ensure that fsck has a vaguely sensible idea of system time at boot and won't complain that the last-modified time in the filesystem is not hugely in the past or future. Some users may not worry about this too use case, in which case it is possible to modify the init system configuration to move things earlier/later as appropriate. DESCRIPTION fake-hwclock sets and queries a fake "hardware clock" which stores the time in a file. This program may be run by the system administrator di- rectly but is typically run by init (to load the time on startup and save it on shutdown) and cron (to save the time hourly). If no command is given then fake-hwclock acts as if the save command was used. COMMANDS save Save the time to the file. As a sanity check, fake-hwclock will not move the saved clock backwards to a time/date earlier than its own release date. Use "force" to over-ride this check. load Load the time from the file. If force is specified fake-hwclock will move the clock either backwards or forwards. Otherwise it will only move it forwards. FILES /etc/fake-hwclock.data The file used to store the time /etc/init.d/fake-hwclock The init script used to run fake-hwclock on startup and shutdown /lib/systemd/system/fake-hwclock.service systemd service used to run fake-hwclock on startup and shutdown /etc/default/fake-hwclock Settings file for the init script. /etc/cron.hourly/fake-hwclock Cron job used to save the time hourly ENVIRONMENT VARIABLES FILE set the file used by fake-hwclock RETURN VALUES 1 is returned for invalid commands. 0 is returned in all other cases. BUGS This approach can only provide a crude approximation of what a real hardware clock provides. Use of NTP or another method to keep the time in sync is strongly advised. Debian 1 October 2014 FAKE-HWCLOCK(8)
Updated on: 2022-Aug-05