Debian Jessie & Windows 7: Fixing System Clock

The date & time is messed up every time you switch from Windows to Linux?

It's due to Windows setting the system clock to the local time and Linux setting it to the UTC time.

# Solution

Tell Debian to set the system clock to the local time.

• In /etc/adjtime, replace UTC by LOCAL
• Run hwclock --localtime
• Just in case, add UTC=no to /etc/init.d/rcS

Source

Edit - Solution for Linux Mint 18 / newer Ubuntu 15.10 and higher: timedatectl set-local-rtc 1 --adjust-system-clock

# Bonus: What doesn't work?

• DOESN'T WORK: Tell Windows to set the system clock to the UTC time. The registry setting is unreliable.
• DOESN'T WORK: Fake Linux by switching to the UTC timezone while setting your local time anyway. You will encounter various kind of errors (example: The OCSP response is not yet valid (contains a date in the future). (Error code: sec_error_ocsp_future_response) when connecting to https websites with Firefox)