How to execute Unix Command in PL/SQL

Hi All,

Is anyone can guide / know how to execute Unix Command in PL/SQL ?
Below is the sample program.

Appreciate anyone can help or guide. Thanks.


CREATE OR REPLACE PROCEDURE P_ARCHIVE_FILE

IS EXC_MESSAGE EXCEPTION;

BEGIN

-- Zip abc.txt to abcYYYYMMDD.txt
HOST('mv abc.txt abc20131231.txt');
HOST('gzip abc20131231.txt');

END;