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Chapter 22. Setting Shell Limits for Your Oracle User

Most shells like Bash provide control over various resources like the maximum allowable number of open file descriptors or the maximum number of processes available to a user. For more information on ulimit for Bash, see man bash and search for ulimit.
If you just install a small test database, then you might be fine with the current settings. Please note that the limits very often vary from system to system. But for larger, production databases, you should increase the following shell limits to the following values recommended by Oracle:
nofile = 65536
To verify the above command execute ulimit -n.
nproc  = 16384
To verify the above command execute ulimit -u.
The nofile option denotes the maximum number of open file descriptors, and nproc denotes the maximum number of processes available to a single user.
To see all shell limits, execute:
ulimit -a
The following procedures and links show how to increase these parameters for the oracle user account: