Creating a service name on linux using vi.

[xmanlinux ] $echo $ORACLE_HOME
/u01/app/oracle/OraHome_1
[xmanlinux ] $cd /u01/app/oracle/OraHome_1/network/admin
[xmanlinux ] $ls
listener.ora samples shrept.lst sqlnet.log sqlnet.ora tnsnames.ora
[xmanlinux ] $vi tnsnames.ora

Copy this to the end of the file and modify appropriately.

JADUONGTNS =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.1)(PORT = 1521))
)
(CONNECT_DATA =
(SERVER = SHARED)
(SERVICE_NAME = XE)
)
)