A script to download and install Firefox to /opt

update-firefox.sh

#!/bin/bash -ex

if [ "$UID" != "0" ]; then
	sudo "$0"
	exit
fi

d="$(mktemp -d)"
cd "$d"

trap "rm -rf $d" EXIT 

wget --content-disposition 'https://download.mozilla.org/?product=firefox-latest-ssl&os=linux64&lang=en-US'

fv="$(ls -1 firefox-*.tar.*)"
f="${fv//.tar.*}"

if [ -z "$fv" ]; then
	echo "No firefox-*.tar.bz2 found! Problem while downloading?"
	exit 1
fi

if [ -d "/opt/$f" ]; then
	echo "Downloaded version ${f#firefox-} already installed!"
	exit 0
fi

tar xvaf "$fv"

if [ ! -d firefox ]; then
	echo "Cannot find a 'firefox' directory after extracting downloaded archive!"
	exit 2
fi

mv firefox "/opt/$f"
cd /opt
ln -sfT "$f" firefox

echo "Firefox ${f#firefox-} installed successfully!"