/usr/share/postgresql/10/extension/pglogical.control is in postgresql-10-pglogical 2.1.1-1.
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 7 | # pglogical extension
comment = 'PostgreSQL Logical Replication'
default_version = '2.1.1'
module_pathname = '$libdir/pglogical'
relocatable = false
schema = pglogical
|