In a folder containing multiple wordpress installations, it cycles all of the websites and updates core, plugins and themes

batch-wordpress-updater.sh

#!/bin/bash

echo "Updating wp-cli to its latest version..."
sudo wp cli update

echo ""
for d in */ ; do
    user=$(stat -c '%U' $d)
    echo ""
    echo "Entering $d with user $user..."
    cd $d
    sudo -u $user wp core update
    sudo -u $user wp plugin update --all
    sudo -u $user wp theme update --all
    cd ..
done