ubuntu@pi2:~$ cat create 
#!/bin/sh

set -eu

ROOT=$SNAP_COMMON/classic

if [ -d $ROOT ]; then
    echo "classic already enabled"
    exit 1
fi

if [ $(id -u) -ne 0 ]; then
    echo "This script needs to be called as root" >&2
    exit 1
fi

# FIXME: confinement will prevent this
echo "Creating classic environment"
VERSION="$(/bin/readlink /snap/ubuntu-core/current)"
SNAPROOT="/var/lib/snapd/snaps/ubuntu-core_${VERSION}.snap"
/usr/bin/unsquashfs -d $ROOT $SNAPROOT
mkdir $ROOT/snappy

# enable
sudo chroot $ROOT /var/lib/classic/enable.sh

# copy important config
for f in hostname timezone localtime; do
    cp -a /etc/writable/$f $ROOT/etc/writable
done
for f in hosts; do
    cp -a /etc/$f $ROOT/etc/
done


# don't start services in the chroot on apt-get install
cat <<EOF > "$ROOT/usr/sbin/policy-rc.d"
#!/bin/sh
while true; do
    case "\$1" in
      -*) shift ;;
      makedev) exit 0;;
      x11-common) exit 0;;
      *) exit 101;;
    esac
done
EOF
chmod 755 "$ROOT/usr/sbin/policy-rc.d"

# workaround bug in livecd-rootfs
chmod 1777 "$ROOT/tmp"