Ugh. I can’t count how many times this one’s bit me, and frustratingly kept my cron scripts from running – always without error, or notice, or even warning, no matter how many logs I scour!
While it may be different on other systems, Ubuntu at least uses the run-parts command to execute scripts in the /etc/cron.hourly, cron.daily, cron.weekly, and cron.monthly directories. Which is all well and good.
Unless, like me, you’re addicted to file extensions.
All of my shell scripts get a .sh file extension. Yeah, I know, not necessary in Linux, but I find it useful to be able to tell at a quick glance at the output of ls exactly what I’m looking at.
Unfortunately, by default, run-parts will only include scripts whose names contain only letters (upper- or lower-case), numbers, underscores, and hyphens. Put a period and a file extension on your script? Won’t be picked up by run-parts, and therefore won’t be executed by your cron.
Fortunately, it’s an easy fix: scriptname.sh just becomes scriptname. I just wish there were some feedback in the logs telling me why a script is being skipped entirely, because I forget about this every single time I write a new script!