Red hat Linux + TIME ZONE CONFIGURATION + details from clock file

With the introduction of RHEL 7 the timezone is managed through systemd, which provides a custom utility to change the timezone: timedatectl

To list all available time zones:

timedatectl list-timezones

To actually change the time zone, (as root or using sudo):

timedatectl set-timezone time_zone

timedatectl set-timezone will not only make the modified time zone take effect immediately, but will also update the /etc/localtime symlink to make that change persistent across reboots.

So the "correct" way to set the clock (at least prior to RHEL 7) is to edit /etc/sysconfig/clock and then run tzdata-update which will then update /etc/localtime; you've just done that step manually.