Unix utility to run a command after a specific length of time has elapsed?

Question

I'm looking for a daemon that will run a command once every week. But I am not looking for something like cron that will run a command at a specific time. Because my laptop is turned off a lot, it happens a lot that that command will not run, because it simply misses the moment that cron runs that command.

Thus, I am looking for a daemon that I can tell to run a command whenever it has been a week (or any other amount of time) since it has ran that command.

I have been searching around a lot for such a utility, but I have not been able to find it. So, does anyone here know such a utility?

Answer 1

OK, so if you created a cron entry like this for the relevant user (your question wasn't very specific with the spec):

0/5 * * * * /path/to/script

and script looks something like this and you do chmod +x /path/to/script

#!/bin/bash
set -x
today=$(date -d "today 00:00" "+%s")
if [[ -s ~/cronflag && -f  ~/cronflag ]]; then
  if [[ $(( $today - $(cat  ~/cronflag ) )) -ge 604800 ]]; then
    echo huzzah!
#    /path/to/weekly
    echo $today > ~/cronflag
    exit 0
  fi
else
#  /path/to/weekly
  echo hip-hop huzzah!
  echo $today > ~/cronflag
  exit 0
fi

you should be able to get your desired result presuming that a) you add the thing you want done weekly in both spots where you see # /path/to/weekly (without the # ;}) and b) the machine usually gets an uptime of >= 10 minutes.