How do I find the current system timezone?

Question

On Linux, I need to find the currently configured timezone as an Olson location. I want my (C or C++) code to be portable to as many Linux systems as possible.

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Answer 1

On Linux, I need to find the current timezone as an Olson location. I want my (C or C++) code to be portable to as many Linux systems as possible.

If you want to be portable, then use only GMT internally. Due to multi-user heritge, *NIX system clock is normally is in GMT and there is no system wide timezone - because different users connected to the system might be living in different timezones.

The user specific timezone is reflected in TZ environment variable and you might need to use that only when converting internal date/time into the user readable form. Otherwise, localtime() takes care of it automatically for you.