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Last active April 16, 2023 19:38
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Add a help target to a Makefile that will allow all targets to be self documenting
# Add the following 'help' target to your Makefile
# And add help text after each target name starting with '\#\#'
help: ## Show this help.
@fgrep -h "##" $(MAKEFILE_LIST) | fgrep -v fgrep | sed -e 's/\\$$//' | sed -e 's/##//'
# Everything below is an example
target00: ## This message will show up when typing 'make help'
@echo does nothing
target01: ## This message will also show up when typing 'make help'
@echo does something
# Remember that targets can have multiple entries (if your target specifications are very long, etc.)
target02: ## This message will show up too!!!
target02: target00 target01
@echo does even more
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prwhite commented Aug 9, 2022

Here is how cargo-quickinstall does it in it's current Makefile

.PHONY: help
help: ## Display this help screen
	@grep -E '^[a-z.A-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'

Simple and efficient, here is the result

If your makefile has something like:

-include .env

your proposal will display:

Makefile                       Display this help screen

Here's my fix for that:

.PHONY: help
help:	## Show this help.
	@grep -hE '^[A-Za-z0-9_ \-]*?:.*##.*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'

Added -h to hide the file name and tweaked the regex to include numbers and possible whitespace before the target's :, although it still doesn't cover all of the possible characters in a target identifier.

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nothub commented Aug 14, 2022

To golf a little bit more, the grep expression of the previous post can be shrinked down to grep -hP '^[\w \-]*?:.*##.*$$' with the perl regex flag and \w that is an alias for [a-zA-Z0-9_].

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just to add another variant to the pile..

  • uses only sed for pre-processing the makefile
  • uses tput to detect if we should use colour
  • uses column for what it does best
	@sed \
		-e '/^[a-zA-Z0-9_\-]*:.*##/!d' \
		-e 's/:.*##\s*/:/' \
		-e 's/^\(.\+\):\(.*\)/$(shell tput setaf 6)\1$(shell tput sgr0):\2/' \
		$(MAKEFILE_LIST) | column -c2 -t -s :

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arvenil commented Dec 1, 2022

What's the most cross-platform solution, without colors and which displays targets even if they don't have comment?

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mathieu-aubin commented Dec 7, 2022

@arvenil i might be wrong but i think that a makefile works using the same system, across all platforms? Please correct me if i am wrong, i am not very cross platform myself... As for color, i guess the terminal will be responsible for displaying it (or not) depending on the context. Many tools have the ability to force the suppression of color, too.

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lpsantil commented Dec 7, 2022

@arvenil Depends on what you want to depend on? You have choices. awk, sed, grep, bash, sh, zsh, GNU Make, BSD Make, Linux, MacOS, BSD, WSL, RHEL/Fedora, Debian, Ubuntu, others. For widest cross compatibility, GNU Make and bash are fairly safe. But bash has been losing install base and mind share with MacOS and other smaller Linux distros changing their default shells.

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lpsantil commented Dec 7, 2022

One other note, since GNU Make is the most popular, it has a fairly powerful and underutilized optional integration of GNU Guile. GNU Guile is language in the Scheme & Lisp family of languages.

If Guile is a bridge too far, then consider bash's BASH_REMATCH facility.

It'll be a bit more code (file I/O, regexes, file parsing, etc) and you'll have to maintain it rather than depending on other well tested tooling like awk, sed, grep.

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lpsantil commented Dec 8, 2022

@arvenil A bit of golfing and I got this to sort of work with the only deps being GNU make and bash

.PHONY: help help_target-funky+names.0k and_with_2_targets_and_spaces_like_bison
help_target-funky+names.0k and_with_2_targets_and_spaces_like_bison: ## Funky ones & bison dual target display ok
        echo "bad - why are you not displaying?"
help: ## bash help
help: ## moar bash help
        @RE='^[a-zA-Z0-9 ._+-]*:[a-zA-Z0-9 ._+-]*##' ; while read line ; do [[ "$$line" =~ $$RE ]] && echo "$$line" ; done <$(MAKEFILE_LIST) ; RE=''

Which for make help outputs

$ make help
help_target-funky+names.0k and_with_2_targets_and_spaces_like_bison: ## Funky ones & bison dual target display ok
help: ## bash help
help: ## moar bash help

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