Linux Command-Line for Beginners: What's happening on this machine

• w [options]

  Show who is logged on and what they are doing.

• who [OPTION]... [ FILE | ARG1 ARG2 ]

  Print information about users who are currently logged in.

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• top / htop

  display Linux processes

• ss [ OPTIONS ] [ FILTER ]

  investigate sockets

  -t, --tcp        display only TCP sockets

  -u, --udp display only UDP sockets

  
  

  -n, --numeric        don't resolve service names

  -l, --listening        display listening sockets

  -p, --processes        show process using socket