Helper to fix broken "apt-get install -f", which might happen when upgrading from i386 to amd64

fix-broken.sh

#!/bin/bash
#
# Public Domain
#
# If you follow https://wiki.debian.org/CrossGrading you might get stuck
# at the "apt-get install -f" step.  Either you are doomed, or use this script here.
#
# Just run it to find out the troublesome :i386 packages.
# Then paste those packagenames to the script here to install the amd64 counterpart.
# Or press just return to run "apt-get install -f",
# which might suddenly kick in and do it's job.
#
# For this to work "apt-get" must have the right architecture, already.

STDOUT() { local e=$?; printf %q "$1"; [ 1 -lt $# ] && printf ' %q' "${@:2}"; printf '\n'; return $e; }
STDERR() { STDOUT "$@" >&2; }
OOPS() { STDERR OOPS: "$@"; exit 23; }
x() { "$@"; }
o() { x "$@" || OOPS "err$?:" "$@"; }
v() { local -n v="$1"; v="$(o ${@:2})" || OOPS var "$1" failed; }


fixer()
{
case "$1" in
('')			STDERR empty package name; return;;
(-*|*[^a-z0-9.-]*)	STDERR wrong package name "$1"; return;;
esac

[ -d "$1" ] &&	STDERR double listed "$1" && return;

o mkdir "$1"
o cd "$1"
o apt-get download "$1"
x dpkg -i "$1"*.deb
}

fix()
{
case "$1" in
(*..*)		OOPS wrong TMP dir "$1";;
(/tmp/*)	;;
(*)		OOPS wrong TMP dir "$1";;
esac

o cd "$1"
for b in "${@:2}"
do
	o cd "$1"
	fixer "${b%.}"
done
o rm -rf "$1"
}

show=:
while	o cd /
	$show && x apt-get install -f
	show=false
	read -p 'PACKAGE(s): ' -ra pack
do
	[ 0 = "${#pack[@]}" ] && { show=:; continue; }

	v DIR mktemp -d
	fix "$DIR" "${pack[@]}"
done