cdh
cd network
cd admin
cat tnsnames.ora
vi tnsnames.ora
orcl_2=
(DESCRIPTION=
(CONNECT_TIMEOUT=10)(RETRY_COUNT=3)
(ADDRESS=(PROTOCOL=tcp)(HOST=mmm111.example.com)(PORT=1622))
(CONNECT_DATA=
(SERVICE_NAME=orcl.example.com)))
sqlplus system/oracle@orcl_2