- List dirs and file count, to find dir with high file count.
      for i in /home/*; do echo $i; find $i | wc -l; done
      for i in /*; do echo $i; find $i | wc -l; done
    - Report space usage of the top level subdirectories.
      du -h --max-depth=2
    - Report space summary only, no directory output.
      du -s -h
    - Find out which device a directory is in.
      df /tmp
      df /home
    - Print of tree of directories
      tree .
    - Disk
      fdisk -l,  list disk partitions
      lsblk,  show a tree of disks, partitions, and lvm volumes
      lsblk -d,  show physical devices
      lsblk -io KNAME,TYPE,SIZE,MODEL,  name/type/size/model