Hi,
Sometimes You can get “ORA-12555: TNS:permission denied ” error.
Details of error are as follows.
ORA-12555: TNS:permission denied
mkdir /var/tmp/.oracle chmod 01777 /var/tmp/.oracle chown root /var/tmp/.oracle chgrp root /var/tmp/.oracle
then add it and try to start Listener again.
[oracle@msdbadm01 ~]$ lsnrctl start LISTENER
Check listener status as follows, it is listening the Database and its service as follows.
[oracle@msdbadm01 ~]$ lsnrctl status LSNRCTL for Linux: Version 18.0.0.0.0 - Production on 28-APR-2020 15:44:29 Copyright (c) 1991, 2019, Oracle. All rights reserved. Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521)) STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for Linux: Version 18.0.0.0.0 - Production Start Date 25-MAR-2020 20:34:20 Uptime 33 days 19 hr. 10 min. 8 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Listener Parameter File /u01/grid/network/admin/listener.ora Listener Log File /u01/app/grid/diag/tnslsnr/vfxidb01/listener/alert/log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER))) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.63.34)(PORT=1521))) Services Summary... Service "+APX" has 1 instance(s). Instance "+APX1", status READY, has 1 handler(s) for this service... Service "+ASM" has 1 instance(s). Instance "+ASM1", status READY, has 1 handler(s) for this service... Service "+ASM_DATA" has 1 instance(s). Instance "+ASM1", status READY, has 1 handler(s) for this service... Service "+ASM_RECO" has 1 instance(s). Instance "+ASM1", status READY, has 1 handler(s) for this service... Service "MSDB" has 1 instance(s). Instance "MSDB1", status READY, has 1 handler(s) for this service... Service "MSDBXDB" has 1 instance(s). Instance "MSDB1", status READY, has 1 handler(s) for this service... [oracle@msdbadm01 ~]$
Or Clear the /var/tmp/.oracle (Linux or Solaris) or (on AIX), /tmp/.oracle directory and start from fresh:
Stop all listeners
Remove the /var/tmp/.oracle or /tmp/.oracle directory, e.g. run the following from the root account as follows.
rm -rf /var/tmp/.oracle
Check the listener(s) configuration contains unique keys specified for each IPC endpoint and each listener
Start the listener(s) from the normal Oracle OS user.
Clearing the /var/tmp/.oracle or /tmp/.oracle directory will force the listeners to recreate the socket files from fresh, each with its own correct ownership.
Do you want to learn more details about RMAN, then read the following articles.
https://ittutorial.org/rman-backup-restore-and-recovery-tutorials-for-beginners-in-the-oracle-database/