Makefile user interaction

gistfile1.txt

# Make the clean target work without having to specify anything
ifneq ($(filter clean,$(MAKECMDGOALS)),)
    IMPORTANT_PARAMETER=none
endif

ifndef IMPORTANT_PARAMETER
    INTERACT_WITH_USER=1
endif

ifeq ($(INTERACT_WITH_USER),1)
    $(info IMPORTANT_PARAMETER not specified, use defaults(none)?)
    USER_AGREES := $(shell read -p "Use defaults? [Y/n]: " REPLY ; echo $$REPLY)
    ifeq ($(strip $(USER_AGREES)),)
        USER_AGREES = y
    endif
    ifneq ($(filter Y y, $(USER_AGREES)),)
        IMPORTANT_PARAMETER ?= none
    else
        $(error Build stopped!)
    endif
endif