Question

I have the following in the makefile:

RESULT=ab
nums:
    number=1 ; while [[ $$number -le $(DIRS_NUM) ]] ; do \

        now=`echo $(CURR_DIR) | cut -d "/" -f 1-$$number` ;\

        **RESULT = $$now;\**

        echo $(RESULT);\

        ((number = number + 1)) ; \    
    done

I would like to update the RESULT variable, but I’m not sure of how to do this.

Answer 1

You cannot update a makefile variable from within a rule. You could use the $(shell cmd) macro to execute a command and get a value out of its output stream, but that’s about as close as you can come. A simple example:

X := $(shell echo 5)

Now X will have the value 5.

Note the use of := here, rather than a simple =. This expands everything on the right side immediately, rather than each time X is referenced.