Just Programmer's Manual

What are the idiosyncrasies of Make that Just avoids?

make has some behaviors which are confusing, complicated, or make it unsuitable for use as a general command runner.

One example is that under some circumstances, make won’t actually run the commands in a recipe. For example, if you have a file called test and the following makefile:

test:
  ./test

make will refuse to run your tests:

$ make test
make: `test' is up to date.

make assumes that the test recipe produces a file called test. Since this file exists and the recipe has no other dependencies, make thinks that it doesn’t have anything to do and exits.

To be fair, this behavior is desirable when using make as a build system, but not when using it as a command runner. You can disable this behavior for specific targets using make’s built-in .PHONY target name, but the syntax is verbose and can be hard to remember. The explicit list of phony targets, written separately from the recipe definitions, also introduces the risk of accidentally defining a new non-phony target. In just, all recipes are treated as if they were phony.

Other examples of make’s idiosyncrasies include the difference between = and := in assignments, the confusing error messages that are produced if you mess up your makefile, needing $$ to use environment variables in recipes, and incompatibilities between different flavors of make.