How to signal a time zone change?

[Peter Steele]

>What's the value of the TZ environment variable for the C apps? You may
need to have them read the new value from somewhere, and then rerun
tzset().

The default value of the TZ environment variable is null. I just tried
passing the explicitly time zone value to the C app and setting TZ to
that value and that seemed to work. I would think that that I should be
able to retrieve that value from /etc/localtime as the docs imply. Guess
not. If I have to pass the time zone to the C app, then I guess that's
what I'll do...