Setting up Oracle XE on Linux

I'm trying to set up oracle-xe on my Linux machine. I just need an environment to play with Oracle SQL; this is not for production. When I try to start SQLPLUS I keep getting one of the following errors: ORA-12541: TNS:no listener ORA-28547: connection to server failed, probable Oracle Net admin error There are quite a few posts regarding similar problems, but even after trying many different "solutions" I'm still lost. I'm probably doing something horribly wrong. See the following outputs: [oracle@roshan ~]$ whoami oracle [oracle@roshan ~]$ pwd /usr/lib/oracle [oracle@roshan ~]$ echo $ORACLE_HOME /usr/lib/oracle/product/11.2.0/xe [oracle@roshan ~]$ echo $ORACLE_SID PLSExtProc [oracle@roshan ~]$ cat product/11.2.0/xe/network/admin/tnsnames.ora # tnsnames.ora Network Configuration File: XE = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = XE) ) ) EXTPROC_CONNECTION_DATA = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE)) ) (CONNECT_DATA = (SID = PLSExtProc) (PRESENTATION = RO) ) ) SQL_AUTHENTICATION_SERVICES = (NONE) [oracle@roshan ~]$ product/11.2.0/xe/bin/lsnrctl start LSNRCTL for Linux: Version 11.2.0.2.0 - Production on 22-OCT-2017 12:24:03 Copyright (c) 1991, 2011, Oracle. All rights reserved. TNS-01106: Listener using listener name LISTENER has already been started [oracle@roshan ~]$ product/11.2.0/xe/bin/lsnrctl status LSNRCTL for Linux: Version 11.2.0.2.0 - Production on 22-OCT-2017 12:24:07 Copyright (c) 1991, 2011, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC_FOR_XE))) STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for Linux: Version 11.2.0.2.0 - Production Start Date 22-OCT-2017 12:21:18 Uptime 0 days 0 hr. 2 min. 48 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Default Service XE Listener Parameter File /usr/lib/oracle/product/11.2.0/xe/network/admin/listener.ora Listener Log File /usr/lib/oracle/diag/tnslsnr/roshan/listener/alert/log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC_FOR_XE))) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=roshan.localdomain)(PORT=1521))) Services Summary... Service "PLSExtProc" has 1 instance(s). Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service... Service "XE" has 1 instance(s). Instance "XE", status READY, has 1 handler(s) for this service... The command completed successfully [oracle@roshan ~]$ sqlplus SYSTEM/foobar@localhost:8080/PLSExtProc SQL*Plus: Release 12.2.0.1.0 Production on Sun Oct 22 12:24:14 2017 Copyright (c) 1982, 2016, Oracle. All rights reserved. ERROR: ORA-12541: TNS:no listener Enter user-name: % [oracle@roshan ~]$ sqlplus SYSTEM/foobar@localhost:1521/PLSExtProc SQL*Plus: Release 12.2.0.1.0 Production on Sun Oct 22 12:24:27 2017 Copyright (c) 1982, 2016, Oracle. All rights reserved. ERROR: ORA-28547: connection to server failed, probable Oracle Net admin error Enter user-name: % [oracle@roshan ~]$ su Password: [root@roshan oracle]# /etc/rc.d/oracle-xe status LSNRCTL for Linux: Version 11.2.0.2.0 - Production on 22-OCT-2017 12:32:06 Copyright (c) 1991, 2011, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC_FOR_XE))) STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for Linux: Version 11.2.0.2.0 - Production Start Date 22-OCT-2017 12:21:18 Uptime 0 days 0 hr. 10 min. 47 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Default Service XE Listener Parameter File /usr/lib/oracle/product/11.2.0/xe/network/admin/listener.ora Listener Log File /usr/lib/oracle/diag/tnslsnr/roshan/listener/alert/log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC_FOR_XE))) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=roshan.localdomain)(PORT=1521))) Services Summary... Service "PLSExtProc" has 1 instance(s). Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service... Service "XE" has 1 instance(s). Instance "XE", status READY, has 1 handler(s) for this service... The command completed successfully Does any of these look very wrong?