On 2019/02/02 6:19, J Freyensee wrote:

System environment variables, like PATH, LD_LIBRARY_PATH, HOME, etc.  Can they ever
default to all lower-case in a Linux Distro, i.e., path, ld_library_path, home, etc?

There is no rule for environment variables, except environment variable name can't
contain '=' because '=' is used as a separator for environment variable value.

If so, is there a mode bit, kernel configuration setting or sysfs file to check for this setting?

No such settings. Just a convention. Even mixed name like OPENSSL_ia32cap is permitted.