bind_mounts () {
  # set defaults
  test -z "$tmpfs_dir" && tmpfs_dir=/var/lib/ltsp-client-setup
  test -z "$rw_dirs" && rw_dirs="/var/cache/man /var/lib/xkb /var/lock /var/run /var/log /var/spool /var/tmp /tmp /var/lib/dbus /etc/reader.conf.d /var/adm /var/lib/dhcpcd /var/lib/misc /media"
  test -z "$copy_dirs" && copy_dirs=""
  test -z "$temp_copy_dirs" && temp_copy_dirs="/var/cache"
  test -z "$bindfiles" && bindfiles="/etc/hosts /etc/X11/xorg.conf /etc/fstab /etc/reader.conf /etc/defkeymap.name /etc/adjtime"
  mount -t tmpfs -o mode=0755 tmpfs $tmpfs_dir
  # preserve directory structure
  for d in $rw_dirs ; do
    if [ -d "$d" ]; then
      cd $tmpfs_dir
      tar --no-recursion -cpf - $(find $d -type d 2> /dev/null) 2> /dev/null | tar xpf -
      mount --bind $tmpfs_dir/$d $d
    else
      echo "WARNING: $d does not exist"
    fi
  done  
  # copy contents into tmpfs
  for d in $copy_dirs $temp_copy_dirs; do
    if [ -d "$d" ]; then
      cd $tmpfs_dir
      tar -cpf - $d 2> /dev/null | tar xpf -
      mount --bind $tmpfs_dir/$d $d
    else
      echo "WARNING: $d does not exist"
    fi
  done
  # mount one file on top of another
  for f in $bindfiles ; do
    if [ -e "$f" ]; then
      mkdir -p "$(dirname $tmpfs_dir/$f)"
      cp $f $tmpfs_dir/$f
      mount --bind $tmpfs_dir/$f $f
    else
      echo "WARNING: $f does not exist"
    fi
  done
}