An example makefile with embedded help messages and dynamic help targets

Makefile

MAKEFILE_PATH := $(abspath $(lastword $(MAKEFILE_LIST)))
ROOT_DIR      := $(patsubst %/,%,$(dir $(MAKEFILE_PATH)))

.PHONY: %/help
%/help: HELP_TARGET = $(subst /help,,$@)
%/help:
	@make -C $(ROOT_DIR) help | grep -Pzo "$(HELP_TARGET)(/\w+)*:.*(\n\s+(.*)?)*\n"

### help: Displays this help message.
.PHONY: help
help:
	@grep -P '^\s*###* ' $(MAKEFILE_LIST) | sed s/'\s*### '// | sed s/'#'/'    '/g

### hello: Just says hello.
#### This target just echos hello. The real intention is to show you the indentation
#### in action. Try using the following command;
##### $ make hello/help
.PHONY: hello
hello:
	@echo hello

### hello/world/foo: Saying hello world foo.
.PHONY: hello/world/foo
hello/world/foo:
	@echo "hello world foo"

### hello/world/bar: Saying hello world bar.
#### You should maybe also try:
##### $ make hello/world/help
.PHONY: hello
hello/world/bar:
	@echo "hello world bar"

This was inspired by the work done at https://gist.github.com/prwhite/8168133