Bash script to install firefox extension xpi (for all users by default)

gistfile1.sh

#!/bin/bash

EXTENSIONSDIR="/usr/lib/firefox-addons/extensions"
TMP="/tmp/firefox-extension-install-temp"

[ x"$1" == "x" ] || [ ! -f $1 ] && echo "Specify valid .xpi file as argument." && exit 1

sudo rm -rf $TMP 2>/dev/null
mkdir -p "$TMP"
trap "sudo rm -rf $TMP 2>/dev/null" 1 2 3 15
unzip "$1" -d "$TMP" &> /dev/null

for token in `cat $TMP/install.rdf` ; do
	echo "$token" | grep "urn:mozilla:install-manifest" &> /dev/null && after_manifest_declaration=true
	if $after_manifest_declaration; then
		if echo "$token" | grep 'em:id=\"' ; then
			extension_id=`echo "$token" | sed 's/.*em:id="\(.*\)".*/\1/'`
		elif echo "$token" | grep '<em:id>' ; then
			extension_id=`echo "$token" | sed 's#.*<em:id>\(.*\)</em:id>.*#\1#'`
		fi
		[ x"$extension_id" == "x" ] || break
	fi
done

rm -rf "$EXTENSIONSDIR/$extension_id" 2>/dev/null
[ x"$extension_id" == "x" ] && echo "Could not determine extension id" && exit 1;
sudo mkdir -p "$EXTENSIONSDIR"
sudo mv "$TMP" "$EXTENSIONSDIR/$extension_id" && echo "$(basename $1) installed to $EXTENSIONSDIR/$extension_id"

sudo rm -rf $TMP 2>/dev/null