- '?') echo "Usage: $0 -t /dev/ttyTX [-r /dev/ttyRX] [-b 9600] [-l 10] [-s 10] [-w]" >&2; exit 250;;
- ':') echo "Missing option argument for -$OPTARG" >&2; exit 251;;
- * ) echo "Unimplemented option: -$OPT" >&2; exit 252;;
+ '?') echo "Usage: $0 -t /dev/ttyTX [-r /dev/ttyRX] [-b 9600] [-l 10] [-s 10] [-w]" >&2; return 250;;
+ ':') echo "Missing option argument for -$OPTARG" >&2; return 251;;
+ * ) echo "Unimplemented option: -$OPT" >&2; return 252;;