Well, I've done a bit of research...
The database documentation for a Linux install has the following:
Resource Shell Limit Resource Soft Limit Hard Limit
Open file descriptors
at least 1024
at least 65536
Number of processes available to a single user
at least 2047
at least 16384
Size of the stack segment of the process
at least 10240 KB
at least 10240 KB, and at most 32768 KB
A generic new user created without anything set for ulimit has the following settings under Oracle Linux 6.5 (a 6.4 that was yum updated to 6.5).
However, the oracle user, created with yum install oracle-rdbms-server-12cR1-preinstall command has the following values:
This is because there is a file that the preinstall script puts into /etc/security/limits.d/ directory named oracle-rdbms-server.12cR1-preinstall.conf.
So, we really don't need to put this into our .bash_profile anymore.
Finally, the whole 'use this if you are using ksh as your shell' is actually wrong too. The -p setting for ulimit is actually a read only parameter in ksh or bash for that matter.