debian inside libreelec

#On computer
apt install debootstrap
debootstrap --arch=armhf buster /debroot http://ftp.debian.org/debian/
tar czf /debroot.tgz /debroot/*
scp /debroot.tgz root@libreelec:/storage/
ssh root@libreelec

#On Rpi3
cd /storage/
tar xzf debroot.tgz
mkdir newroot
mkdir newroot/LibreELEC_root

cat <<EOF > debroot/etc/shells
/bin/sh
/bin/bash
EOF

cat <<EOF > debroot/etc/passwd
root:x:0:0:root:/root:/bin/bash
_apt:x:105:65534::/nonexistent:/usr/sbin/nologin
EOF

echo -n debroot/etc/kernel/postinst.d/apt-auto-removal
chmod +x debroot/etc/kernel/postinst.d/apt-auto-removal

cat <<EOF > debroot/etc/group
root:x:0:
EOF

ln -sf /proc/sys/kernel/hostname debroot/etc/hostname
ln -sf ../LibreELEC_root/run/connman/resolv.conf debroot/etc/resolv.conf
ln -sf ../LibreELEC_root/run/libreelec/hosts debroot/etc/hosts

cat <<EOF > launch_debian.sh
mount --bind /storage/debroot /storage/newroot/
/storage/debroot/usr/bin/unshare --mount -- /storage/launch_debian_stage2.sh
umount /storage/newroot
EOF

cat <<EOF > launch_debian_stage2.sh
INIT=/bin/bash #change to /sbin/init later

cd newroot
./usr/sbin/pivot_root .  LibreELEC_root/
mount -t sysfs sysfs /sys
mount -t proc proc /proc
mount -t devpts devpts /dev/pts/
unshare -fp --mount-proc $INIT
umount /dev/pts
umount /proc
umount /sys
EOF

chmod +x launch_debian.sh launch_debian_stage2.sh