How do you get the list of targets in a makefile?

Question

I\'ve used rake a bit (a Ruby make program), and it has an option to get a list of all the available targets, eg

> rake --tasks
rake db:charset      # ret         


        

Answer 1

To expand on the answer given by @jsp, you can even evaluate variables in your help text with the $(eval) function.

The proposed version below has these enhanced properties:

• Will scan any makefiles (even included)
• Will expand live variables referenced in the help comment
• Adds documentation anchor for real targets (prefixed with # TARGETDOC:)
• Adds column headers

So to document, use this form:

RANDOM_VARIABLE := this will be expanded in help text

.PHONY: target1 # Target 1 help with $(RANDOM_VARIABLE)
target1: deps
    [... target 1 build commands]

# TARGETDOC: $(BUILDDIR)/real-file.txt # real-file.txt help text
$(BUILDDIR)/real-file.txt:
    [... $(BUILDDIR)/real-file.txt build commands]

Then, somewhere in your makefile:

.PHONY: help # Generate list of targets with descriptions
help:
    @# find all help in targets and .PHONY and evaluate the embedded variables
    $(eval doc_expanded := $(shell grep -E -h '^(.PHONY:|# TARGETDOC:) .* #' $(MAKEFILE_LIST) | sed -E -n 's/(\.PHONY|# TARGETDOC): (.*) # (.*)/\2  \3\\n/'p | expand -t40))
    @echo
    @echo ' TARGET   HELP' | expand -t40
    @echo ' ------   ----' | expand -t40
    @echo -e ' $(doc_expanded)'