Skip `apt-get update` if you've recently updated cache

update-apt.sh

function getLastAptGetUpdate()
{
    local -r aptDate="$(stat -c %Y '/var/cache/apt')"
    local -r nowDate="$(date +'%s')"

    echo $((nowDate - aptDate))
}
# Default To 24 hours
updateInterval="$((24 * 60 * 60))"
lastAptGetUpdate="$(getLastAptGetUpdate)"
if [[ "${lastAptGetUpdate}" -gt "${updateInterval}" ]]
then
    sudo apt-get update
else
    #lastUpdate="$(date -u -d @"${lastAptGetUpdate}" +'%-Hh %-Mm %-Ss')"

    echo "Skip apt-get update because it was run within ${updateInterval}sec"
fi