I also have tried this commands in the LINUXTARGET:
[delphix@linuxtarget ~]$ free -m
total used free shared buffers cached
Mem: 1877 735 1141 5 53 469
-/+ buffers/cache: 212 1664
Swap: 303 0 303
[delphix@linuxtarget ~]$ lsnrctl status
LSNRCTL for Linux: Version 11.2.0.2.0 - Production on 24-MAR-2016 07:51:39
Copyright (c) 1991, 2011, Oracle. All rights reserved.
Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for Linux: Version 11.2.0.2.0 - Production
Start Date 24-MAR-2016 06:13:25
Uptime 0 days 1 hr. 38 min. 14 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Listener Log File /u01/app/oracle/diag/tnslsnr/linuxtarget/listener/alert/log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=linuxtarget)(PORT=1521)))
The listener supports no services
The command completed successfully
[delphix@linuxtarget ~]$ sqlplus delphixdb/delphixdb@XEXE
SQL*Plus: Release 11.2.0.2.0 Production on Thu Mar 24 08:27:55 2016
Copyright (c) 1982, 2011, Oracle. All rights reserved.
ERROR:
ORA-12154: TNS:could not resolve the connect identifier specified
Enter user-name: ERROR: