Creates a live debian on the provided (already partitioned) device

livedeb

#!/bin/bash

DEV=${1?must specify a device}

function finish {
    for d in boot dev/pts dev proc sys; do
        if test -d "$PWD/usbroot/$d" && mount | grep -q "$PWD/usbroot/$d"; then
            umount "$PWD/usbroot/$d"
        fi
    done

    if test -d usbroot; then
        if mount | grep -q "$PWD/usbroot"; then
            umount "./usbroot"
        fi
        rmdir usbroot
    fi
}

ROOT_FS_TYPE=ext4
DEBIAN_RELEASE=stretch
LINUX_VERSION=4.9.0-9-amd64

set -e -x

: "Check that $DEV has partitions ${DEV}1 (boot) and ${DEV}2 (root)"
sfdisk -V "$DEV"
test -b "${DEV}1" -a -b "${DEV}2"

: Set partition table properties
sfdisk --part-type "$DEV" 1 83
sfdisk --part-type "$DEV" 2 83
sfdisk -A "$DEV" 1

: Create filesystems
mkdosfs -n LINUXBOOT "${DEV}1"
"mkfs.${ROOT_FS_TYPE}" -F "${DEV}2"
UUID1=$(blkid "${DEV}1" | sed -n 's/.*\<UUID="\([0-9a-fA-F-]\+\)".*/\1/p')
UUID2=$(blkid "${DEV}2" | sed -n 's/.*\<UUID="\([0-9a-fA-F-]\+\)".*/\1/p')

trap finish EXIT

: Mount root
mkdir -p usbroot
mount -t "$ROOT_FS_TYPE" "${DEV}2" usbroot

: Build boot partition
VMLINUX_FILENAME="vmlinuz-${LINUX_VERSION}"
INITRD_FILENAME="initrd.img-${LINUX_VERSION}"
syslinux "${DEV}1"
cat /usr/lib/SYSLINUX/mbr.bin > "$DEV"
mkdir -p usbroot/boot
mount -t vfat "${DEV}1" ./usbroot/boot
cat <<END > usbroot/boot/syslinux.cfg
default linux
timeout 1
prompt 1
label linux
    kernel $VMLINUX_FILENAME
    append initrd=$INITRD_FILENAME root=UUID=$UUID2 ro
END

: Build root partition
mkdir -p usbroot/etc
cat <<END > usbroot/etc/fstab
UUID=$UUID2 /     $ROOT_FS_TYPE defaults,noatime 0 0
UUID=$UUID1 /boot vfat defaults         0 0
END
export DEBIAN_FRONTEND=noninteractive
if ! [ -f "${DEBIAN_RELEASE}.tar" ]; then
    debootstrap --make-tarball="${DEBIAN_RELEASE}.tar" "$DEBIAN_RELEASE" tmp http://ftp.debian.org/debian
fi
debootstrap "--unpack-tarball=$PWD/${DEBIAN_RELEASE}.tar" "$DEBIAN_RELEASE" usbroot http://ftp.debian.org/debian
mount -t devtmpfs dev     ./usbroot/dev
mount -t devpts   devpts  ./usbroot/dev/pts
mount -t proc     proc    ./usbroot/proc
mount -t sysfs    sysfs   ./usbroot/sys
chroot usbroot apt-get install --no-install-recommends -y \
    rsync \
    tshark tcpdump \
    smartmontools \
    dosfstools \
    ntfs-3g \
    locales \
    aptitude \
    lvm2 \
    cryptsetup \
    busybox-static \
    kbd console-setup \
    linux-image-amd64 \
    syslinux
echo livedeb > usbroot/etc/hostname
chroot usbroot /bin/bash -c 'echo "root:root" | chpasswd'

: root password is root
: To test: qemu-system-x86_64 -m 512 -hda "$DEV"