https://blog.lateral.io/2017/01/create-azure-vhd-ubuntu-mac-os-x/

create-vm

#!/bin/bash
# Create a VirtualBox VM from an Ubuntu Cloud Image
# Thanks to https://gist.github.com/smoser/6066204
name=$1

# URL to most recent cloud image of 14.04
# If you want a different version just find the URL from https://cloud-images.ubuntu.com/
img_url="https://cloud-images.ubuntu.com/trusty/current"
img_url="${img_url}/trusty-server-cloudimg-amd64-disk1.img"

img_dist="${img_url##*/}"
img_raw="${img_dist%.img}.raw"
disk="$name.vdi"

# Download the img
wget $img_url -O "$img_dist"

# Convert it to raw
qemu-img convert -O raw "${img_dist}" "${img_raw}"

# Create VirtualBox 'vdi' from raw
VBoxManage convertfromraw "$img_raw" "$disk"
rm "${img_raw}"

seed_iso="seed.iso"

# Create meta-data file
cat > meta-data <<EOF
local-hostname: localhost
EOF

# Create user-data file
cat > user-data <<EOF
#cloud-config
password: ubuntu
chpasswd: { expire: False }
ssh_pwauth: True
EOF

# Create seed.img to use the above to files to config the new instance on boot
gtruncate --size 100K seed.img
mkisofs -output seed.img -volid cidata -joliet -rock user-data meta-data
qemu-img convert -f raw -O raw seed.img "$seed_iso"
rm user-data meta-data seed.img

# Create the virtual machine
VBoxManage createvm --name "$name" --register

# Set RAM to 2048 MB
VBoxManage modifyvm "$name" --memory 2048

# Set the (dynamic) disk size to 30 GB
VBoxManage modifyhd "$disk" --resize 30720

# Set up NAT and port forwarding for SSH
VBoxManage modifyvm "$name" --nic1 nat --natpf1 "ssh,tcp,,2222,,22"

# Attach HD with disk image
VBoxManage storagectl "$name" --name SATA --add sata
VBoxManage storageattach "$name" --storagectl SATA --device 0 --port 0 --type hdd --medium "$disk"

# Attach ISO with seed.iso
VBoxManage storagectl "$name" --name IDE --add ide
VBoxManage storageattach "$name" --storagectl IDE --port 0 --device 0 --type dvddrive --medium "$seed_iso"