Makefile help (list available make targets)

Makefile-help

# have an intermediate _help, to move the actual help target to the file end
_help: help

#= Section 1

target1:
	echo target1

target2: target1
	echo target2

target3: target2 # target 3 description
	echo target3

target4: # target 4 description
	echo target4

#= Miscellaneous
help: # Shows this help message
	@sed -nr \
		-e 's/^#= (.*)/\n\n\1:/p' \
		-e 's/^([^_][_a-zA-Z0-9-]*):([^#]*)(# (.*))?/  \1|\4/p' \
		${MAKEFILE_LIST} \
		| column -t -s '|'

adapted from https://stackoverflow.com/a/76822685/2808520