Makefile help generator

Makefile

.DEFAULT_GOAL := help

# use '# >>> Build commands' to create section
# use '# target: target description' to create help for target

# example output from this file:
# $ make
# Usage:
# 
# >>> Section 1
#  - option1                             help for option 1
#  - option2                             help for option 2
# 
# >>> Section 2
#  - option3                             help for option 3
#

.PHONY: help
help:
	@echo "Usage:"
	@cat $(MAKEFILE_LIST) | grep -E '^# >>>|^# [A-Za-z0-9_.-]+:' | sed -E 's/^# //' | awk ' \
		BEGIN { \
			green="\033[32m"; \
			yellow="\033[33m"; \
			reset="\033[0m"; \
			section=""; \
		} \
		/^>>>/ { \
			section=substr($$0, 5); \
			printf "\n" green ">>> %s" reset "\n", section; \
			next; \
		} \
		/^([A-Za-z0-9_.-]+):/ { \
			target=$$1; \
			gsub(/:$$/, "", target); \
			description=substr($$0, index($$0, ":") + 2); \
			if (description == "") { description="-"; } \
			printf " - " yellow "%-35s" reset " %s\n", target, description; \
		} \
	'

# >>> Section 1
# option1: help for option 1
# option2: help for option 2

# >>> Section 2
# option3: help for option 3
option3:
	@echo 'option3'