drupal update with drush

cd /var/www/drupaldirectroy
# Backup everything (codebase + database)
drush arb
# get a list of all modules:
drush up -s
# filter it to just those needing an update:
drush up -s | grep -i update
# filter again for just security updates:
drush up -s | grep “SECURITY UPDATE”
# get a count of security updates, suitable for piping to a monitoring system like nagios or a command to send an email:
drush up -s | grep “SECURITY UPDATE” | wc -l