Simple PhantomJS installer for Linux

install-phantomjs.sh

#!/bin/sh
set -e

if [ "$(id -u)" -ne 0 ]; then
	printf 'WARNING: You will most likely need to be root, but continuing anyway ...\n' >&2
fi

url="$1"
if [ -z "$url" ]; then
	printf 'Please go to <http://phantomjs.org/download.html> and find the\n'
	printf 'Linux (32/64 bit) .tar.bz2 download URL, paste it and hit return:\n'
	printf '\nURL: '
	read -r url
fi

version="$(echo "$url" | sed -e 's#^.*/phantomjs-\([0-9.]*\)-linux-[^/]*\.tar\.bz2$#\1#')"
if [ -z "$version" ]; then
	printf 'Sorry, I could not extract the version number from that URL.\n' >&2
	exit 1
fi

basepath='/usr/local/bin'
lnkfile='phantomjs'
lnkpath="$basepath/$lnkfile"
outfile="$lnkfile-$version"
outpath="$basepath/$outfile"

PS4="$(basename "$0")> "
set -x

curl -L "$url" | tar xj --anchored --wildcards --strip-components=2 --to-stdout 'phantomjs-*-linux-*/bin/phantomjs' >"$outpath"
chmod 0755 "$outpath"
ln -sf "$outfile" "$lnkpath"