[tz] Re: Is $TZ valid?

[Paul Eggert via tz]

On 2026-07-19 17:07, Paul Gilmartin via tz wrote:
Any ideas?  This must have been done before.

The POSIX spec provides no way to check whether a TZ setting is valid. 
That is, behavior is undefined when TZ is invalid.

tzcode provides a way: if tzalloc("ABC") returns a null pointer and 
errno has a value other than ENOMEM, then "ABC" is invalid. So if you're 
on platforms like NetBSD that have tzalloc, you have a way. Or you can 
copy tzcode and use its tzalloc.