ovldiff

#!/bin/sh
set -eu

CWD="$(dirname "$0")"
OVL="${1:-$PWD/iso/LiveOS/overlay}"

sqfs="$(realpath -m "$OVL/../squashfs.img")"
test -f "$sqfs"

tmp="$(mktemp -d)"
mkdir "$tmp/dev" "$tmp/ovl"
mount -o ro "$sqfs" "$tmp/dev"
mkdir -p "$OVL" "$OVL/../ovlwork"
mount -o lowerdir="$tmp/dev",upperdir="$OVL",workdir="$OVL/../ovlwork" -t overlay overlay "$tmp/ovl"

( cd "$tmp/ovl"
    find etc \! -type d \! -type l \
        \! -path 'etc/csh.env' \
        \! -path 'etc/environment.d/10-gentoo-env.conf' \
        \! -path 'etc/group' \
        \! -path 'etc/group-' \
        \! -path 'etc/gshadow' \
        \! -path 'etc/gshadow-' \
        \! -path 'etc/passwd' \
        \! -path 'etc/passwd-' \
        \! -path 'etc/profile.env' \
        \! -path 'etc/shadow' \
        \! -path 'etc/shadow-' \
    | sort | xargs -I% diff -Nu ../dev/% %
)

umount "$tmp/ovl" "$tmp/dev"
rm -r "$tmp"