What is the primary function of the 'lsof' command?

The primary function of the 'lsof' command is to provide a list of open files. In Linux and Unix-like operating systems, files can be anything from regular files, directories, and block devices to network sockets. The 'lsof' command enables users to see which files are currently open by which processes. This is particularly useful for troubleshooting issues related to file locks, identifying what processes are using particular files, and monitoring system performance.

By listing open files, the command can also assist in managing system resources and diagnosing problems, such as files that are not being released properly by processes. This functionality is essential for system administrators and developers to effectively monitor and control their systems. The other options represent different types of information that can be obtained through other commands, but they do not encapsulate the primary purpose of 'lsof'.