Suppose that you want to set or change linux local timezone to UTC:
cp /etc/sysconfig/clock /etc/sysconfig/clock.bak
echo -e "ZONE=\"UTC\"\nUTC=true\nARC=false" > /etc/sysconfig/clock
mv /etc/localtime{,.bak}
ln -s /usr/share/zoneinfo/UTC /etc/localtime
echo 'export TZ=UTC' >> /etc/profile
Now run "date" to confirm it's UTC:
[root@andy-doxer ~]# date
Mon Aug 20 07:10:17 UTC 2018