esac
done
-# usefull commands are resume and archive
+# only tested commands are resume and archive
cmd_arg=${1:-run}
+case $cmd_arg in
+ run|resume|archive) : ;;
+ *) die "untested command arg" ;;
+esac
+
+if (( $# > 1 )); then
+ die: "only 1 nonoption arg is supported"
+fi
+
if [[ -v targets && $source ]]; then
die "error: -t and -s are mutually exclusive"
fi