just some general remarks
- Files in /etc/cron.*/ are not allowed to have file endings, hence rename abc.sh to abc
- Take care it has the shebang #!/bin/bash (or whichever shell works), as those files are not explicitly executed with a specific shell.
- Take care it is executable: chmod +x /etc/cron.hourly/abc
- Check if it would be executed: run-parts --test /etc/cron.hourly/
I hope /etc/crontab.hourly was a typo on your post, as it would need to be /etc/cron.hourly