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/get_pacstrap

@@ -0,0 +1,29 @@
+#!/bin/sh
+
+# Finds pacstrap in $PATH, or download some version of it if not found.
+# This script prefers to use local copies that are already downloaded, over
+# system-wide installations, in case you want to test on some specific
+# outdated version of pacstrap.
+
+LOCALDIR=`pwd`/arch-install-scripts
+if test -e "$LOCALDIR/pacstrap"
+then
+    echo "Found $LOCALDIR/pacstrap in current directory"
+
+    # Run pacstrap without installing it to the system.
+    bash "$LOCALDIR/pacstrap" "$@"
+elif IT=`command -v pacstrap`
+then
+    echo "Found $IT in PATH"
+
+    # Use the version of pacstrap that was already installed.
+    pacstrap "$@"
+else
+    echo "pacstrap not found. Downloading to $LOCALDIR."
+    git clone https://gitlab.archlinux.org/archlinux/arch-install-scripts
+    make -C arch-install-scripts pacstrap
+
+    # Run pacstrap without installing it to the system.
+    bash "$LOCALDIR/pacstrap" "$@"
+fi
+