getarg.md

shlib / core / getarg()

shlib.getarg

Given an option from the cmdline, extract the argument for --foo bar style arguments as well as --foo=bar style arguments, throwing an error if no such argument is found and while protecting against --foo --bar conditions. The idea here is that when a command-line parser has identified a command-line option, this interface can extract the optional argument from the option, or from the argument following the option. If an argument is not found then an error is thrown and program execution is terminated.

Example:

while test "$#" -gt '0'; do
	case "${1}" in
	(-a|-arg|--arg|--arg=*)
		OPTARG="$(shlib.getarg "${1}" "${2}")"
		echo "argument=${OPTARG}";;
	esac
	shift
done

In the above example the argument may follow $1, or it may be embedded as part of $1, as in the case of --arg=Hello. The getarg() routine will parse $1 to extract the = condition. If no argument is found it will then evaluate $2 to see if it starts with a -, if it does not, then getarg returns $2, else an error is reported and the program terminates.

See also: optarg