Hi Stephen,
On Wed Sep 30, 2026 at 6:51 AM CEST, Stephen Kitt wrote:
Regarding the latter, TZ=UTC isn’t “technically invalid”. POSIX allows
three formats for TZ values:
* :characters
* std offset dst offset, rule
* “a format specifying a geographical timezone or a special timezone”
UTC0 matches the second one. UTC matches the third, and is perfectly
valid.
The main benefit of UTC0 is that it is fully specified in POSIX; on
any POSIX-compliant system, TZ=UTC0 will mean the same thing. TZ=UTC
relies on the implementation; typically it would use the IANA database
(which is mentioned in POSIX), but there’s nothing stopping an
implementation from interpreting TZ=UTC as the timezone of a putative
“United Transcendental Countries” for example.
Oh, I didn't think about that. You're absolutely correct!
I will still be preferring UTC0 for the reasons you mention, but your
comment saved me from starting a mental fight against the usage of
TZ=UTC :)
And also today, I learned something new. Thanks all!
