added commands for qemu images

README.md

@@ -1,3 +1,12 @@
 # bootstrap
 
 The script in this repo bootstraps Debian bullseye from a grml live environment. Design decisions and usage instructions are outlined in the beginning of the script.
+
+
+## Prepare qemu images
+```
+img="/var/lib/libvirt/images/ts-linux-testing.qcow2"
+qemu-img create -f qcow2 -o size=20G $img  # create image
+qemu-nbd -c /dev/nbd0 $img  # create device from image
+qemu-nbd -d /dev/nbd0       # release device
+```