read input variable in makefile and set variable upon it`s name

makefile gnu-make

armezit · Aug 29, 2012 · Viewed 24.6k times · Source

I have a makefile where I want to read module name from input and then make directory based on it`s name. here is my code:

build:  
    @read -p "Enter Module Name:" module;  
    module_dir=./modules/$$module  
    mkdir -p $$module_dir/build;

But after setting module_dir, it contains only ./modules/ (with no module name concatenated).
What is wrong in my code?

thanks for your answers

Answer

Each command runs in its own subshell, so variables can't survive from one command to the next. Put them on the same line and they'll work:

build:  
    @read -p "Enter Module Name:" module; \  
    module_dir=./modules/$$module; \
    mkdir -p $$module_dir/build