Change `mruby-config` to print usage on invalid arguments.
Or no argument at all.
MODIFY
mrbgems/mruby-bin-config/mruby-config
mrbgems/mruby-bin-config/mruby-config
#!/bin/sh
+print_help()
+{
+ echo "Usage: mruby-config [switches]"
+ echo " switches:"
+ echo " --cflags print flags passed to compiler"
+ echo " --cflags print flags passed to compiler"
+ echo " --cflags print flags passed to compiler"
+ echo " --ldflags print flags passed to linker"
+ echo " --ldflags-before-libs print flags passed to linker before linked libraries"
+ echo " --libs print linked libraries"
+ echo " --libmruby-path print libmruby path"
+ echo " --help print this help"
+ exit 0
+}
+
+if [ $# -eq 0 ]; then
+ print_help
+fi
+
while [ $# -gt 0 ]; do
case $1 in
--cflags) echo MRUBY_CFLAGS;;
@@ -7,14 +26,7 @@ while [ $# -gt 0 ]; do
--ldflags-before-libs) echo MRUBY_LDFLAGS_BEFORE_LIBS;;
--libs) echo MRUBY_LIBS;;
--libmruby-path) echo MRUBY_LIBMRUBY_PATH;;
- --help) echo "Usage: mruby-config [switches]"
- echo " switches:"
- echo " --cflags print flags passed to compiler"
- echo " --ldflags print flags passed to linker"
- echo " --ldflags-before-libs print flags passed to linker before linked libraries"
- echo " --libs print linked libraries"
- echo " --libmruby-path print libmruby path"
- exit 0;;
+ *) print_help;;
esac
shift
done

Change `mruby-config` to print usage on invalid arguments.

Or no argument at all.