#!/bin/sh -e

if [ ! -d /var/lib/apt/lists ] \
    || [ -n "$( find /etc/apt -newer /var/lib/apt/lists )" ] \
    || [ ! -f /var/cache/apt/pkgcache.bin ] \
    || [ "$( stat --format %Y /var/cache/apt/pkgcache.bin )" -lt "$( date +%s -d '-1 day' )" ]
then
    echo 'update'
fi