gistfile1.txt

from: bin/initdb --data-checksums -D $bdir
...
The database cluster will be initialized with locale "en_US.UTF-8".
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".

from: bin/initdb --data-checksums -D $bdir --locale-provider=builtin --builtin-locale=C.UTF-8
...
The database cluster will be initialized with this locale configuration:
  locale provider:   builtin
  default collation: C.UTF-8
  LC_COLLATE:  en_US.UTF-8
  LC_CTYPE:    en_US.UTF-8
  LC_MESSAGES: en_US.UTF-8
  LC_MONETARY: en_US.UTF-8
  LC_NUMERIC:  en_US.UTF-8
  LC_TIME:     en_US.UTF-8
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".