The problem is quite simple: you need to run a script on a regular basis, so you put it in one of the directories of the /etc/cron.{daily,weekly,monthly} hierarchy but for some reason cron just seems to ignore it.

First, check that the script is really where you think it is, that it is executable (or else chmod a+x yourscript to make it so) and that it’s name does contain only letters, numbers, underscores and hyphens. In fact, a script named run.me won’t be run because of the dot.

You can get the list of the scripts that are eligible to run with:

$ run-parts --test /etc/cron.daily

You can change the argument /etc/cron.daily to any other directory.

My News Sniffer project needs to regularly do some back-end stuff like checking a bunch of rss feeds and downloading web pages. I do this with some rake tasks, which I call using the cron daemon.  Recently I’ve been having problems where some tasks take a bit longer than usual to complete and end up running in parallel. This slows things down, which means more tasks end up running in parallel and then my little virtual machine eventually falls on it’s face under memory pressure.