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This question already has an answer here:

Edit by OP: Yes, the community is correct. The question indeed is a duplicate of this one. I missed it in my search. Thank you for pointing me there.

I've been noticing a peculiar issue with Ubuntu recently, in that booting to Ubuntu from Windows seems to be messing with the System time.

Eg: I shutdown Windows at 8:35pm, to boot into Ubuntu. When Ubuntu was started up, instead of showing time as 8:35 pm, it showed 3:05 pm momentarily, before setting itself to 8:35pm. If Windows is restarted after this happens, time now becomes 3:05pm (which seems to be UTC time)

If Windows alone is restarted (Meaning booting up Windows after shutting down Windows), no time fluctuation occurs. If Ubuntu is started up after Windows is shutdown, the same issue happens. Time seems momentarily UTC, and then corrected within a second or so after startup, to correct time. However the next time Windows is booted up, the time becomes the same as that which was momentarily displayed on Ubuntu. I hope I'm making this clear.

I've checked that my timezone is correct in Ubuntu. It is set as Asia/Kolkata. I even did a dpkg-reconfigure tzdata, but it was already correct timezone.

My timezone is Asia/Kolkata, which is UTC+5.30 hours. The time which appears incorrectly is the correct time if my timezone was UTC. I have a Multiboot with grub2, managing Ubuntu 13.04 and Windows 8. PC is an Acer Aspire V5-121 Netbook purchased two days ago.

I'd love any help with deciphering this apparently weird mystery.

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marked as duplicate by Eric Carvalho, Basharat Sialvi, bcbc, Uri Herrera, Radu Rădeanu Jun 8 '13 at 7:48

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Is time set correctly in the BIOS? – Mitch Jun 7 '13 at 15:34
@Mitch The Bios time resets to whatever time is current showed in Windows or Linux, i.e while restarting Windows Bios time is correct, and once Ubuntu is booted to, and then restarted, Bios time changes to the incorrect time. – Droidzone Jun 7 '13 at 15:41
What happens if you boot Ubuntu first time, then reboot? – horIzoN Jun 7 '13 at 16:07
@nerof61: If I reboot toUbuntu from Ubuntu, there isnt any issue. Same thing while rebooting to Windows from Windows. It's Ubuntu to Windows that creates the issue. As I mentioned, even in Ubuntu, the KDE Clock widget displays incorrect time only momentarily. A few seconds later, it displays correct time. – Droidzone Jun 7 '13 at 16:11
Same problem here with Kubuntu 13.04 and Windows XP dual boot. It dives me crazy. And not only time in Kubuntu rolls back to UTC, my Windows XP time roll backs too! – – Green Aug 2 '13 at 5:22
up vote 3 down vote accepted

In the past I fixed such issues in dualboot environments by modyfying the following variable in /etc/default/rcS:

# assume that the BIOS clock is set to UTC time (recommended)
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