setregdomain sets the regulatory domain for your system; it takes no arguments and is normally called via system script (eg, udev) rather than manually by an administrator.
The regulatory domain is represented by an ISO / IEC 3166-1 alpha2 country code. By default, setregdomain attempts to determine the appropriate country code by examining the target of the /etc/localtime symbolic link. That information is used to look-up the matching country code in the /usr/share/zoneinfo/zone.tab file.
The country code look-up may fail. This could be due to faulty or incomplete information in the /usr/share/zoneinfo/zone.tab file, or the use of an actual file rather than a symlink for /etc/localtime , among other possibilities. In those cases the system administrator should define a COUNTRY environment variable in the /etc/sysconfig/regdomain file. This value will be used as the country code and the country code look-up will be skipped.
/etc/sysconfig/regdomain /etc/localtime /usr/share/zoneinfo/zone.tab