qemu-img

# Create disk image with a specific size (in gigabytes):
$ qemu-img create image_name.img gigabytesG

# Show information about a disk image:
$ qemu-img info image_name.img

# Increase or decrease image size:
$ qemu-img resize image_name.img gigabytesG

# Dump the allocation state of every sector of the specified disk image:
$ qemu-img map image_name.img

# Convert a VMware .vmdk disk image to a KVM .qcow2 disk image:
$ qemu-img convert -f vmdk -O qcow2 path/to/file/foo.vmdk path/to/file/foo.qcow2