Makefile $(command) not working but `command` did

Question

The thing is when I was writing a Makefile for my project, when I needed to detect the current branch name, in a make rule I did this :

check_branch:
    if         


        

Answer 1

Inside recipes you have to escape dollar signs in order to get them interpreted by the shell. Otherwise, Make treats $(git ...) as a built-in command or a variable and tries to evaluate it (of course, unsuccessfully).

check_branch:
    if [ "$$(git rev-parse --abbrev-ref HEAD)" == "master" ]; then \
    ...

Answer 2

In shell lines, you write shell commands as you would in a shell script. That's why the second operation works.

If you want Make to evaluate git command outside of the shell, you can enclose the operation in a shell function, as in:

$(shell git rev-parse --abbrev-ref HEAD)

And you ought to be good to go, though I often implement this kind of thing as:

branch := $(shell git rev-parse --abbrev-ref HEAD)
target:dep
     mkdir -p build/$(branch)

Or something along those lines.