To mount dmg:

hdiutil mount Test.dmg


To unmount:

hdiutil unmount /Volumes/Test


To convert DMG to compressed:

hdiutil convert Test.dmg -format UDZO -o Test_compressed.dmg


To convert compressed DMG to R/W:

hdiutil convert Test_compressed.dmg -format UDRW -o Test.dmg


To rename a volume:

diskutil rename /Volumes/NameA NameB