lsof command is an advanced Unix command that is typically not installed with a Unix/Linux distro but can be easily obtained from standard package repositories in most of modern OS distributions.
lsof stands for list open files, but since everything in Unix is a file, you get a lot more than just a list of files open by a given process.
What lsof Is Great For
- Show all the network connections open on your system (with process names to see what is responsible for each connection)
- Show list of files open on the operating system or single process level
- Confirm what is using a specific file or directory
- Confirm what is using a particular network port