dual-boottimewindows
I have a dual boot and a I configured windows to use UTC with a registry fix as explained in here: Clock time is off on dual boot
Now, I need to come back to localtime again, and I have no idea about how to edit the windows' registry to make it use local time again.
Edit the file /etc/default/rcS with your favorite text editor, ie:
sudo nano /etc/default/rcS
Look for the UTC=foo (yes/no) line and change it to UTC=yes.
From the rcS(5) man page:
UTC
This is used to govern how the hardware real time clock is interpreted when it is read (e.g., at boot time, for the purpose of setting the system clock) and when it is written (e.g., at shutdown). If this option is set to no then the system clock is assumed to be set to local time. If the option is set to yes then the system clock is assumed to be set to something approximating Coordinated Universal Time (UTC). (POSIX systems keep a variant of UTC, without leap seconds.)
Hardware clock is on UTC time
If your hardware clock is using UTC time, the system needs to know it! Change the UTC configuration of the clock in the /etc/default/rcS file to yes. The system will presume your clock is UTC and apply offset accordingly. Of course, your clock should also have the correct time. Once this is set, with hwclock --set --date="02/07/2015 10:21:00" (--date should be provided with the local time, even if the hardware clock use UTC) your system should use the correct time. Now you can use ntp daemon, for example to keep your clock on time.
Best Answer
On my Windows 7 machine, the default is for
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\RealTimeIsUniversalto not exist. So, here are Windows instructions:Hold down the Windows logo key and press R. There, type
regedit. Click OK and if you're using Vista or newer, acknowledge the UAC warning.Now, in the left pane, there is a tree view. Under
Computer, there will be some things calledHKEY_SOMETHING_OR_OTHER. You should click the + next toHKEY_LOCAL_MACHINE. Then, you should click the + next toSYSTEMto get inoHKEY_LOCAL_MACHINE\SYSTEM. Now, expandCurrentControlSet, then inside it,Control, and thenTimeZoneInformation. Now, right-click the entry forRealTimeIsUniversaland select the option to delete it. Alternatively, you could set it's value to 0.