gnu make: list the values of all variables (or “macros”) in a particular run

Question

How can I list the current value of all variables (also called macros) in a Makefile when running make?

E.g. if this is in the Makefile:

CUR-DIR := $         


        

Answer 1

Thanks to @kevinf for the foreach solution -- if one wants to export this list as a somewhat machine-readable file, one will have a hard time with uneven quotes or newlines when using echo or printf, since Make isn't able to quote the data correctly -- one needs to use the $(file ...) function to write the data to avoid sh/bash complaining about invalid syntax. For example, use this in your rule -- it prints variable name, definition and expanded value:

$(file > $(MAKEFILE_ENV_FILE),)
$(foreach v, $(.VARIABLES), \
    $(file >> $(MAKEFILE_ENV_FILE),$(v)) \
    $(file >> $(MAKEFILE_ENV_FILE),    := $(value $(v))) \
    $(file >> $(MAKEFILE_ENV_FILE),    == $($(v))) \
    $(file >> $(MAKEFILE_ENV_FILE),) \
)

(This will still not allow to always distinguish malicious variables with double newlines from two variables, for this one now add a sufficiently unique separator infront of each Makefile-generated newline just after each comma inside $(file >> NAME,TEXT))

Set MAKEFILE_ENV_FILE to some filename, e.g.:

MAKEFILE_ENV_FILE := $(abspath $(lastword $(MAKEFILE_LIST))).env