Is there any way to throw errors or warnings in a korn shell script to prevent the use of unset variables ? Let's assume I have a temporary folder that I want to remove. TEMP_FILES_DIR='/app/myapp/tmp' rm -Rf $TEMP_FILE_DIR #notice the misspelling How to prevent this kind of mistakes before they actually happen? I know the script should check for file existence and empty string before attempting to remove, this is just a silly example to illustrate a mistake that could have been avoided with some warnings. I don't know if this feature exists in ksh. If it does exist, how do you turn it on?