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When Ubuntu Linux and Windows are used together and if the time zone is not UTC and when the computer is rebooted into Windows after Ubuntu Linux is used the time gets changed as the BIOS clock gets reset to UTC. For example if the time zone that is set in Ubuntu Linux is GMT +5.30 hrs then after Ubuntu Linux’s usage the time in BIOS clock would be set to UTC time i.e. the BIOS clock would be +5.30 hrs behind the Ubuntu Linux’s time but if you boot into Ubuntu Linux it will automatically adjust to the local time where as the time on Windows will be the UTC time which can cause issues with Windows.

The difference is the way Ubuntu Linux and Windows handle time, Windows considers the BIOS clock of the computer to be the local time where as Ubuntu considers it as UTC time. To solve this we would have to set Ubuntu Linux to consider the hardware or BIOS clock as local time

How to Prevent Ubuntu Linux from Resetting or Changing Computer’s BIOS Clock

In the following steps you can find the steps to set the hardware clock as local time in Ubuntu.

1. Open the terminal and enter the following command:

sudo gedit /etc/default/rcS

2. In the gedit window that opens ups find the the line UTC=yes and change it to UTC=no

After you make the changes it should look like this:

After you make the changes save the data using the save button. That’s  it now the Ubuntu Linux will treat the hardware or BIOS clock as the local time and the alternate boots between Windows & Ubuntu Linux should not cause issues with time.