#!/bin/bash

# make sure you had
# apt install qemu qemu-user-static binfmt-support
# before you do this

# Write the raspbian image onto the sd card,
# boot the pi so it expands the fs, then plug back to your laptop/desktop
# and chroot to it with this script 
# Invoke:
# sudo ./chroot-to-pi.sh /dev/sdb

# mount partition
mount -o rw ${1}2  /mnt/raspbian
mount -o rw ${1}1 /mnt/raspbian/boot

# mount binds
mount --bind /dev /mnt/raspbian/dev/
mount --bind /sys /mnt/raspbian/sys/
mount --bind /proc /mnt/raspbian/proc/
mount --bind /dev/pts /mnt/raspbian/dev/pts

# ld.so.preload fix
sed -i 's/^/#/g' /mnt/raspbian/etc/ld.so.preload

# copy qemu binary
cp /usr/bin/qemu-arm-static /mnt/raspbian/usr/bin/

# chroot to raspbian
chroot /mnt/raspbian /bin/bash

# You will be taken to the bash command line now
# So do whatever you need to do
# and issue 
# exit 
# when you're done

# revert ld.so.preload fix
sed -i 's/^#//g' /mnt/raspbian/etc/ld.so.preload

# unmount everything
umount /mnt/raspbian/{dev/pts,dev,sys,proc,boot,}