Script to check latest riot-web release and update it

update_riot.sh

#!/bin/zsh

# This script assumes you have a symlinked riot installation, eg
# /var/www/html/riot -> /var/www/html/riot-v0.11.4
#
# If the local version is older than the github version, it
# downloads the latest release, extracts it, copies
# config.json and home.html from old to new, removes
# the old symlink and sets a new one 

ATOM="https://github.com/vector-im/riot-web/releases.atom"
HTDOCS="/var/www/html/"

WGET=`which wget`
XMLSTARLET=`which xmlstarlet`

[ ! -x "$WGET" ] && echo "wget not found" >&2 && exit 1
[ ! -x "$XMLSTARLET" ] && echo "xmlstarlet not found" >&2 && exit 1


VERSION_GH=$($WGET -qO- $ATOM|$XMLSTARLET sel -N atom="http://www.w3.org/2005/Atom" -t -m '/atom:feed /atom:entry[1]' -v 'atom:title' -n)
VERSION_LO=$(readlink ${HTDOCS}/riot|cut -d- -f2-|sed 's:/$::')

[ $VERSION_LO = $VERSION_GH ] && echo "already newest version $VERSION_LO" && exit 1

cd $HTDOCS
$WGET -q https://github.com/vector-im/riot-web/releases/download/${VERSION_GH}/riot-${VERSION_GH}.tar.gz -O${VERSION_GH}.tar.gz
tar zxf ${VERSION_GH}.tar.gz
NEWDIR=`tar ztf ${VERSION_GH}.tar.gz --exclude \*/\*`
cp riot-${VERSION_LO}/config.json ${NEWDIR}
cp riot-${VERSION_LO}/home.html ${NEWDIR}
cp riot-${VERSION_LO}/welcome.html ${NEWDIR}
rm riot
ln -s ${NEWDIR} riot
echo Updated from $VERSION_LO to $VERSION_GH >&2