One thing I try to do is retrieve information from the system instead of hardcoding it. For example, instead of USER=mail UID=8 use USER=mail

One thing I try to do is retrieve information from the system instead of hardcoding it. For example, instead of USER=mail UID=8 use USER=mail UID=$(id -u $USER) It improves portability and removes potential sources of errors. Also note that this is something that should be done in any programming language, not just shell scripts.