ANONYMOUS wrote: Keep in mind that make does not understand (or perform) any compiling or linking - it simply determines (reads) what relationships exist, and then executes actions (shell commands). There's not even any requirement that the actions produce the target (though they usually do). So if we have: then make doesn't know of any relationship between x.o and y.h, and there's no required C file. But if y.h is newer than x.o, or if x.o does not exist, then the actions are executed.