Calibre - split RPi from others to use raspbain's testing repo, split off unstable

scripts/calibre-install-unstable.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+# Thanks to Jerry Vonau (https://github.com/jvonau) who made
+# this critical breakthrough possible!
+# might break future updates, you have been warned
+# The latest available is 3.20 available from testing
+# https://packages.debian.org/search?keywords=calibre
+# might break future updates, you have been warned
+
+export DEBIAN_FRONTEND=noninteractive
+# Updates to calibre & calibre-bin to "very latest" 3.x from unstable
+echo "deb http://deb.debian.org/debian unstable main" >> /etc/apt/sources.list.d/unstable.list
+apt update
+apt -y install calibre calibre-bin
+# Remove last line, safer than: rm /etc/apt/sources.list.d/debian-unstable.list
+sed -i '$ d' /etc/apt/sources.list.d/unstable.list
+# Clears the cache of testing and unstable
+apt update