arch scripts

It took a moment to work out that there is actually no way of
bootstrapping an arch environment without permanently installing things
to the host system! So we just download a live image and unpack it.

Then after that, getting erlang to work was very easy, just install it,
install zx, run. No R26 incompatibility problems, life is good!

arch/cleanup

@@ -0,0 +1,102 @@
+#!/bin/sh
+
+if test `id -u` -ne 0
+then
+    echo "$0 must be run as root."
+    return
+fi
+
+set -e
+
+FRESH=clean_environment
+ROOT=test_environment
+
+add_mount() {
+    if mountpoint -q "$ROOT$1"
+    then
+        echo "$ROOT$1 already mounted."
+    else
+        echo "Mounting $2$1 to $ROOT$1"
+        mkdir -p "$ROOT$1"
+        mount -o bind "$2$1" "$ROOT$1"
+    fi
+}
+
+remove_mount() {
+    if mountpoint -q "$ROOT$1"
+    then
+        echo "Unmounting $ROOT$1"
+        umount -l "$ROOT$1"
+    fi
+}
+
+add_mounts() {
+    add_mount / "$ROOT"
+    add_mount /proc
+    add_mount /sys
+    add_mount /dev
+    add_mount /dev/pts
+    add_mount /tmp/.X11-unix
+}
+
+remove_mounts() {
+    remove_mount /tmp/.X11-unix
+    remove_mount /dev/pts
+    remove_mount /dev
+    remove_mount /sys
+    remove_mount /proc
+    remove_mount /
+}
+
+remove_environment() {
+    if test -d "$ROOT"
+    then
+        # Call this script that automatically unmounts the mount points too.
+        remove_mounts
+        echo "Removing $ROOT"
+        rm -r "$ROOT"
+    else
+        echo "No environment found at $ROOT. Doing nothing."
+    fi
+}
+
+remove_everything() {
+    if test -d "$ROOT"
+    then
+        # Call this script that automatically unmounts the mount points too.
+        remove_environment
+    fi
+
+    if test -d "$FRESH"
+    then
+        echo "Removing $FRESH"
+        rm -r "$FRESH"
+    fi
+
+    if test -d debootstrap
+    then
+        echo "Removing debootstrap"
+        rm -r debootstrap
+    fi
+
+    if test -f pkglist.x86_64.txt
+    then
+        echo "Removing pkglist.x86_64.txt"
+        rm pkglist.x86_64.txt
+    fi
+
+    if test -f archlinux-bootstrap*.tar.zst
+    then
+        echo "Removing archlinux bootstrap tarballs."
+        rm archlinux-bootstrap*.tar.zst
+    fi
+}
+
+case "$1" in
+    everything)  remove_everything ;;
+    mounts)      remove_mounts ;;
+    add_mounts)  add_mounts ;;
+    environment) remove_environment ;;
+    "")          remove_environment ;;
+esac
+