I just want to know how to install the module pg_tgrm as used in the trigram indexing scheme that allows you to do un-anchored search patterns on an index.

WHERE foo LIKE '%bar%';


pg_trgm is an extension, so:
CREATE EXTENSION pg_trgm;

If you get the following error

ERROR:  could not open extension control file ".../extension/pg_trgm.control":
No such file or directory"

then you need to install the module for your operating system. For example:

Ubuntu/Debian:
  sudo apt install postgresql-contrib


Redhat/Centos
  sudo dnf install postgresql12-contrib


Fedora
  sudo dnf install postgresql-contrib


FreeBSD
  sudo pkg install postgresql12-contrib



Of course, "12" can be replaced with whatever version number is appropriate.
