bug#79714: env: always adds __CF_USER_TEXT_ENCODING var on macOS since v9.8

Paul Eggert <[email protected]> writes:

> On 2025-11-02 01:24, Bruno Haible via GNU coreutils Bug Reports wrote:
>> We could document that users should not use environment variables
>> that start with "__"
>
> In addition to Pádraig's qualms, POSIX says[1] that if an environment
> variable's name consists solely of uppercase ASCII letters, '_', and
> non-initial digits, the variable might affect the behavior of standard
> utilities like 'cat'. So if we document environment variable gotchas,
> we should document that one too.

That sounds like a good idea, but I am not too sure where it would be
placed since it applies to all programs. Perhaps the Coreutils FAQ
should be revived [1]?

Collin

[1] https://www.gnu.org/software/coreutils/faq/coreutils-faq.html#uname-is-system-specific