Shell: Checking if argument exists and matches expression
As long as the file is in the correct YYYY-MM.tar.gz format, it obviously is non-empty and ends in .tar.gz as well. Check with a regular expression:
if ! [[ $1 =~ [0-9]{4}-[0-9]{1,2}.tar.gz ]]; then echo "Argument 1 not in correct YYYY-MM.tar.gz format" exit 1fiObviously, the regular expression above is too general, allowing names like 0193-67.tar.gz. You can adjust it to be as specific as you need it to be for your application, though. I might recommend
[1-9][0-9]{3}-([1-9]|10|11|12).tar.gzto allow only 4-digit years starting with 1000 (support for the first millennium ACE seems unnecessary) and only months 1-12 (no leading zero).