My customer has a question: Why does the handle count obtained from lsof -u username | wc -l differ from the results shown by ulimit -n and ulimit -Hn ? What exactly does the nofile setting defined in /etc/security/limits.conf represent? Ultimately, they want to configure a system-level handle limit and a user-level handle limit, and then be able to check how many handles the current user has already used to monitor whether they are approaching the limit.