Check the actual ulimits for all the running Oracle instances

I’ve read the recent good post from my friend Rene on Pythian’s Blog about how to troubleshoot when user ulimits are different from what specified in limits.conf:

Quick Tip : Oracle User Ulimit Doesn’t Reflect Value on /etc/security/limits.conf

I would like to add my 2 cents:

Once you fix the problem, you may want to check (any maybe monitor) when an instance is running with a wrong value (and maybe encounter the famous Error message: Linux-x86_64 Error: 23: Too many open files in system).

This single line gives you an overview of all your instances at once:

If you find any wrong values, plan a restart before you encounter any error during peak hours!