localtime — Local timezone configuration file
/etc/localtime -> ../usr/share/zoneinfo/…
The /etc/localtime file configures the
    system-wide timezone of the local system that is used by
    applications for presentation to the user. It should be an
    absolute or relative symbolic link pointing to
    /usr/share/zoneinfo/, followed by a timezone
    identifier such as "Europe/Berlin" or
    "Etc/UTC". The resulting link should lead to the
    corresponding binary
    tzfile(5)
    timezone data for the configured timezone.
Because the timezone identifier is extracted from the
    symlink target name of /etc/localtime, this
    file may not be a normal file or hardlink.
If /etc/localtime is missing, the
    default "UTC" timezone is used.
The timezone may be overridden for individual programs by
    using the $TZ environment variable. See
    environ(7).
You may use timedatectl(1) to change the settings of this file from the command line during runtime. Use systemd-firstboot(1) to initialize the time zone on mounted (but not booted) system images.