dnschneid/crouton — pull request #669 by drinkcat (2014-03-03 12:54:31+00:00)
Title: start*/enter-chroot: Make sure options with missing arguments are detected

Mark the end of user specified parameters with `""`.

Makes sure commands like `sudo startcli -u` fail instead of outputing confusing messages like `user exec not found`).

--

For reference, there is a neater way to detect empty arguments:
```
if [ -z "$OPTARG" -a "${OPTARG-unset}" != "unset" ]; then
error 2 "$USAGE"
fi
```
but `dash` is not POSIX-compliant in this case, and does not unset `OPTARG`...