2 examples for qemu-img
# create disk image called "four-gigs.img" and is 4000 megabytes in size qemu-img create four-gigs.img 4000m
# covert disk images from or to raw, qcow2, vdi,vmdk, vpc (-p shows progress) $ qemu-img convert -p -f raw -O qcow2 /some/input.img /some/output.qcow2