Can you make valid Makefiles without tab characters?

Question

target: dependencies
    command1
    command2

On my system (Mac OS X), make seems to require that that Makefiles have a tab character

Answer 1

Until GNU Make 4.2

Steven Penny's answer works.

.RECIPEPREFIX +=

The reason why this works is described in my comment.

---

Since GNU Make 4.3 (released on 19 Jan 2020)

Behavior of += operator has been changed in a backward-incompatible way. If the left operand has an empty value, a space is no longer added.

You can instead use

.RECIPEPREFIX := $(.RECIPEPREFIX)

, where is a single space. Although $(.RECIPEPREFIX) is expanded as an empty value, this is needed not to let GNU Make ignore . Note this code works even on GNU Make older than version 4.3.