Use the result of a shell command in a conditional in a makefile

Question

I am trying to execute a command in a conditional in a makefile.

I got it working in a shell:

if [ -z \"$(ls -A mydir)\" ]; then \\
  echo \"empty di         


        

Answer 1

I have little experience in writing makefiles. However I think you must use two dollar signs in your recipe:

all:
    if [ -z "$$(ls -A mydir)" ]; then \

https://www.gnu.org/software/make/manual/make.html#Variables-in-Recipes:

if you want a dollar sign to appear in your recipe, you must double it (‘$$’).

This is an example of output after I changed your makefile and added $$(ls -A mydir):

$ ls mydir/
1

$ make
if [ -z "$(ls -A mydir)" ]; then \
      echo "empty dir"; \
    else \
      echo "non-empty dir"; \
    fi
non-empty dir

$ rm mydir/1

$ make
if [ -z "$(ls -A mydir)" ]; then \
      echo "empty dir"; \
    else \
      echo "non-empty dir"; \
    fi
empty dir