====== Rare Linux commands ======

===== List ports open by a certain application =====

''$ lsof -i 4 -a -p <PID>''

(-i 4 stands for IPv4)

Source: http://www.cyberciti.biz/faq/how-do-i-find-out-what-ports-are-listeningopen-on-my-linuxfreebsd-server/
===== Equivalents to "top" =====

==== I/O ====

$ iotop

==== Network bandwidth ====

$ nethogs