# check now timezone
$ date -R
Sun, 21 Oct 2018 23:35:04 +0800
# change timezone to Shanghai if it is wrong
apt-get update
apt-get install tzdata
echo "Asia/Shanghai" > /etc/timezone
rm -f /etc/localtime
# maybe you need to rm -rf /usr/share/zoneinfo/UTC
dpkg-reconfigure -f noninteractive tzdata
# output
Current default time zone: 'Asia/Shanghai'
Local time is now: Sun Oct 21 22:33:36 CST 2018.