# List all IPv4 network files sudo lsof -i4 # List all IPv6 network files sudo lsof -i6 # To find listening ports: lsof -Pnl +M -i4 # To find which program is using the port 80: lsof -i TCP:80 # List all processes accessing a particular file/directory lsof </path/to/file> # List all files open for a particular user lsof -u <username> # List all files/network connections a given process is using lsof -c <command-name> # See this primer: http://www.danielmiessler.com/study/lsof/ # for a number of other useful lsof tips