Problem:

After installing 11g on Oracle Linux 5 and running SQL*Plus, the following error appears:

sqlplus: error while loading shared libraries: /u01/app/oracle/product/11.1.0/db_1/lib/libnnz11.so: 
cannot restore segment prot after reloc: Permission denied

Solution:

Turn off SELinux. As root user, issue the following command:

/usr/sbin/setenforce 0