update_homebrew.zsh

#!/usr/bin/env zsh
# Automate updateing of brew, to be executed by cronjob.
# It keeps a timestamp of last update. If last update is more than 1 day ago, update will be preformed.
# If last update was within 24 hours, skip this update.
# If `-f` switch is used, it will preform update iregardless of timestamp.

timestampFile="/tmp/brew_update.timestamp"

function updateBrew {
    /usr/local/bin/brew upgrade
    /usr/local/bin/brew cleanup
    touch ${timestampFile}
}

if [ "$1" = "-f" ]; then
    echo "Forced update"
    updateBrew
elif [ !  -f ${timestampFile} ]; then
    echo "First update"
    updateBrew
elif [ $(find -L ${timestampFile} -mtime +1) ]; then
    echo "Last update more than 1 day"
    updateBrew
else
    echo "Skipping this update, as it was updated recently."
fi