😈   >df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/disk3s1    7.8G  855M  6.9G  11% /Volumes/DISK_IMG

😈   >df -h
Filesystem                                            Size  Used Avail Use% Mounted on
/dev/disk3s2                                          6.7G  5.2G  1.6G  78% /Volumes/InstallESD

😈   >sudo diskutil eject /dev/disk3s2
Disk /dev/disk3s2 ejected

😈   >df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/disk3s1    7.8G  932M  6.9G  12% /Volumes/DISK_IMG