Runtime Conditionals in Makefiles

Makefile

# this phony target shows how to use a conditional within a recipe
# this conditional is executed at "run-time"
# rather than at "build-time" which is when the Makefile `ifeq` are evaluated
# notice how everything in the conditional must be joined up as one line
test_conditional:
	@echo 'NESTED CONDITIONAL'
	[ "$$(echo 1)" -lt 2 ] && { \
	  echo 'oh no'; \
	  exit 1; \
	} || { \
	  [ -f issomefilethere ] && { \
	    echo 'true'; \
	  } || { \
	    echo 'false'; \
	  } \
	}

.PHONY test_conditional

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