/usr/share/postgresql/10/extension/earthdistance.control is in postgresql-10 10.3-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | # earthdistance extension
comment = 'calculate great-circle distances on the surface of the Earth'
default_version = '1.1'
module_pathname = '$libdir/earthdistance'
relocatable = true
requires = 'cube'
|