SQL*Plus: Release 11.2.0.2.0 Production on Thu Dec 15 19:54:24 2016

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Enter password:
ERROR:
ORA-12162: TNS:net service name is incorrectly specified

● oracle-xe.service - LSB: Oracle 11g Express Edition
   Loaded: loaded (/etc/init.d/oracle-xe; bad; vendor preset: enabled)
   Active: active (exited) since Thu 2016-12-15 19:26:35 BDT; 22min ago
     Docs: man:systemd-sysv-generator(8)
  Process: 16315 ExecStop=/etc/init.d/oracle-xe stop (code=exited, status=0/SUCCESS)
  Process: 16339 ExecStart=/etc/init.d/oracle-xe start (code=exited, status=0/SUCCESS)

Dec 15 19:26:28 dipu-pc systemd[1]: Starting LSB: Oracle 11g Express Edition...
Dec 15 19:26:28 dipu-pc oracle-xe[16339]: Starting Oracle Net Listener.
Dec 15 19:26:28 dipu-pc su[16357]: Successful su for oracle by root
Dec 15 19:26:28 dipu-pc su[16357]: + ??? root:oracle
Dec 15 19:26:28 dipu-pc su[16357]: pam_unix(su:session): session opened for user oracle by (uid=0)
Dec 15 19:26:28 dipu-pc oracle-xe[16339]: Starting Oracle Database 11g Express Edition instance.
Dec 15 19:26:28 dipu-pc su[16375]: Successful su for oracle by root
Dec 15 19:26:28 dipu-pc su[16375]: + ??? root:oracle
Dec 15 19:26:28 dipu-pc su[16375]: pam_unix(su:session): session opened for user oracle by (uid=0)
Dec 15 19:26:35 dipu-pc systemd[1]: Started LSB: Oracle 11g Express Edition.

Dec 15 19:59:26 dipu-pc systemd[1]: Started CUPS Scheduler.
-- Subject: Unit cups.service has finished start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit cups.service has finished starting up.
--
-- The start-up result is done.
Dec 15 20:06:14 dipu-pc sudo[17609]:     dipu : TTY=pts/0 ; PWD=/home/dipu ; USER=root ; COMMAND=/usr/sbin/service oracle-xe start
Dec 15 20:06:14 dipu-pc sudo[17609]: pam_unix(sudo:session): session opened for user root by (uid=0)
Dec 15 20:06:16 dipu-pc systemd[1]: Started LSB: Oracle 11g Express Edition.
-- Subject: Unit oracle-xe.service has finished start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit oracle-xe.service has finished starting up.
--
-- The start-up result is done.
Dec 15 20:06:16 dipu-pc sudo[17609]: pam_unix(sudo:session): session closed for user root
Dec 15 20:06:21 dipu-pc sudo[17639]:     dipu : TTY=pts/0 ; PWD=/home/dipu ; USER=root ; COMMAND=/bin/journalctl -xe
Dec 15 20:06:21 dipu-pc sudo[17639]: pam_unix(sudo:session): session opened for user root by (uid=0)
Dec 15 20:09:28 dipu-pc sudo[17707]:     dipu : TTY=pts/0 ; PWD=/home/dipu ; USER=root ; COMMAND=/bin/journalctl -xe
Dec 15 20:09:28 dipu-pc sudo[17707]: pam_unix(sudo:session): session opened for user root by (uid=0)