import psycopg2 as pg_driver
import time

conn = pg_driver.connect(host='192.168.xx.xxx',
						 port='5432',
						 user='postgres',
						 password='xxxx',
						 database='postgres'
						 )
query=" \! pg_dump -Fc xx_98_upgrade > /tmp/xxxv_98_upgrade2.dmp"
cur =conn.cursor()
cur.execute(query)
while True:
	row = cur.fetchone()
	if (not row):
		break
	print("%s" % (row))

conn.close()

  backup_directory= db_config[db_instance]['backup_dir']
    query = """dump database {DATABASE_NAME} to '{BACKUP_DIR}{DATABASE_NAME}_{TIME}.dmp'""".format(DATABASE_NAME=schema_name, TIME=cur_time,BACKUP_DIR=backup_directory)
    print(query)
    try:
        conn = sybase_driver.connect(username, password, database)
        cursor = conn.cursor()

        logging.debug(query)
        cursor.execute(query)
        for mess in conn.messages:
            print("%s " % mess[1][0])


        cursor.close()
        conn.close()

        return {'data': {backup_directory+schema_name+'_'+cur_time}, 'error': []}

CREATE OR REPLACE FUNCTION BACKUP_DATABASE(DATABASE_NAME text) RETURNS text AS $BODY$
    use warnings;
    use strict;
    my $DATABASE_NAME = $_[0];
    my $output = `pg_dump -Fc $DATABASE_NAME >/tmp/$DATABASE_NAME `;
    return($output);
$BODY$ LANGUAGE plperlu;

select * from BACKUP_DATABASE('98_upgrade')

-bash-4.2$ ls -l /tmp
total 177328
-rw------- 1 postgres postgres 60522823 Dec 12 15:05 98_upgrade