lsof

Lists open files and the corresponding processes. Note: In most cases, you need root privilege (or use sudo) because you want to list files opened by others.

Find the processes that have a given file open:

lsof {{/path/to/file}}

Find the process that opened a local internet port:

lsof -i :{{port}}

Only output the process PI:

lsof -t {{/path/to/file}}

List files opened by the given use:

lsof -u {{username}}

List files opened by the given command or proces:

lsof -c {{process_or_command_name}}