#!/bin/sh
set -e

newroot=${1:=/mnt}

[ -d "$newroot" ] || : ${error?:$newroot does not exist}

echo "=> ensure directories exist"
mkdir -p \
  "$newroot/proc" \
  "$newroot/sys" \
  "$newroot/dev/pts" \
  "$newroot/run"

echo "=> mount proc"
mount -t proc proc "$newroot/proc"

echo "=> mount sys"
mount -t sysfs sysfs "$newroot/sys"

echo "=> bind dev"
mount -o bind /dev "$newroot/dev"

echo "=> mount devpts"
mount -t devpts devpts "$newroot/dev/pts"

echo "=> bind run"
mount -o bind /run "$newroot/run"

echo "=> chroot"
exec chroot "$newroot" /bin/sh
