element-web auto-updater script

get-latest-element.sh

# element-web auto-updater script by unendingPattern ( unendingpattern.github.io )
#   fetches the latest element (matrix client) release for self-hosting
#   requirements: curl, jq, tar

# cron:
#   @hourly /bin/sh /path/to/get-latest-element.sh
# OR
#   0 * * * * /bin/sh /path/to/get-latest-element.sh

# functions
#   credit: maboloshi ( https://gist.github.com/lukechilds/a83e1d7127b78fef38c2914c4ececc3c#gistcomment-2839301 )
get_latest_release() {
  curl --silent "https://api.github.com/repos/$1/releases/latest" | # Get latest release from GitHub api
    grep '"tag_name":' |                                            # Get tag line
    sed -E 's/.*"([^"]+)".*/\1/'                                    # Pluck JSON value
}
#   credit: yairchu ( https://stackoverflow.com/a/37939589 )
function version { echo "$@" | awk -F. '{ printf("%d%03d%03d%03d\n", $1,$2,$3,$4); }'; }

# code
USR="nginx"
GRP="nginx"
DIR="/var/www/element-web"
NEW=$(get_latest_release vector-im/element-web)
DNL=$(curl -s https://api.github.com/repos/vector-im/element-web/releases/latest | jq --raw-output '.assets[0] | .browser_download_url')
FIL="$(basename -- $DNL)"

if [ -d "$DIR" ]; then
    OLD=$(cat $DIR/version)
else
    OLD="N/A"
    mkdir $DIR
fi

echo "Latest: $NEW | Installed: $OLD"
echo "Install path: $DIR"
echo "Download link: $DNL"
echo "Filename: $FIL"

if [ $(version $NEW) -ge $(version $OLD) ]; then
    curl -LJO $DNL
    tar -C $DIR -xvf $FIL --strip 1
    chown -R $USR:$GRP $DIR
    rm $FIL
    echo "Finished!"
else
    echo "Already up to date."
fi