(For my debian system at least) there is a file /etc/timezone which contains the timezone in ascii. And /etc/localtime is the current timezone file copied from /usr/share/zoneinfo, containing the timezone Als Europe/Amsterdam.
Exactly the data we need. Does this mean your system looks like this:
pike
Pike v7.6 release 6 running Hilfe v3.5 (Incremental Pike Frontend)
Stdio.read_file("/etc/localtime");
(1) Result: "Europe/Amsterdam\n"