mount rpi-sdimg

mount_rpisdimg.sh

# source: https://raspberrypi.stackexchange.com/questions/13137/how-can-i-mount-a-raspberry-pi-linux-distro-image

IMAGE_FILE="YOUR IMAGE FILE GOES HERE"
TMP=$(mktemp -d)
LOOP=$(sudo losetup --show -fP "${IMAGE_FILE}")
sudo mount ${LOOP}p2 $TMP
sudo mount ${LOOP}p1 $TMP/boot/

# do stuff to ${TMP}/ which is rpi filesystem

# cleanup
umount ${TMP}/boot/
umount ${TMP}
rmdir ${TMP}