modify qcow2 image using qemu-nbd

modify-qcow2-image.sh

#!/bin/bash

if [ $# -ne 1 ]; then
    echo "usage: $0 <qcow2 image>"
    exit
fi
image=$1
target=$(mktemp -d)

cleanup_on_exit() {
    exit_code=$?

    umount $target && rm -fr $target
    qemu-nbd --disconnect /dev/nbd0

    exit $exit_code
}
trap "cleanup_on_exit" EXIT

setup() {
    qemu-nbd --connect=/dev/nbd0 $image
    mkdir -p $target
    mount /dev/nbd0p1 $target
    chroot $target
}
setup