CREATE EXTENSION to load the language into the database

Hello team,

We are getting below issue while creating a function in Potsgres 11.2

nagios=# create or replace function diskf (filesystem text, warn int, err int) returns text as $BODY$
nagios$# use warnings;
nagios$# use strict;
nagios$# my $fs = $_[0];
nagios$# my $w = $_[1];
nagios$# my $e = $_[2];
nagios$# my $r = "WARNING";
nagios$# my $output = `df -kP $fs`;
nagios$# $output =~ /.*\s+(\d+)%.*/;
nagios$# $output = $1;
nagios$# if ($output > $w)
nagios$# { $r = "ERROR" if $output > $e;}
nagios$# else { $r = "OK";}
nagios$# return "$r $output";
nagios$# $BODY$ language plperlu;

ERROR: language "plperlu" does not exist
HINT: Use CREATE EXTENSION to load the language into the database.

nagios=# SELECT * FROM pg_language;
lanname | lanowner | lanispl | lanpltrusted | lanplcallfoid | laninline | lanvalidator | lanacl
----------+----------+---------+--------------+---------------+-----------+--------------+--------
internal | 10 | f | f | 0 | 0 | 2246 |
c | 10 | f | f | 0 | 0 | 2247 |
sql | 10 | f | t | 0 | 0 | 2248 |
plpgsql | 10 | t | t | 13075 | 13076 | 13077 |
(4 rows)

To solve this issue , I am getting the below warnings if creating extensions.

nagios=# CREATE EXTENSION plperl;
ERROR: could not open extension control file "/usr/local/share/postgresql/extension/plperl.control": No such file or directory
nagios=# CREATE LANGUAGE plperlu;
ERROR: could not load library "/usr/local/lib/postgresql/plperl.so": Error loading shared library libperl.so.5.20: No such file or directory (needed by /usr/local/lib/postgresql/plperl.so)
nagios=# CREATE LANGUAGE plperlu;
ERROR: could not load library "/usr/local/lib/postgresql/plperl.so": Error loading shared library libperl.so.5.20: No such file or directory (needed by /usr/local/lib/postgresql/plperl.so)
nagios=#

Regards,
Dault