I wanted to run a script every 20 minutes, so I put this into my crontab:
20 * * * * sh script.sh
That's wrong. That only runs it once every hour 20 minutes into the hour. For example, "20,40 * * * * sh bash.sh" would run it twice - 20 and 40 minutes into the hour.
To run the script every 20 minutes like I was expecting:
*/20 * * * * sh script.sh