A rule such as this should not be placed at the beginning of the
makefile, because we do not want it to run by default! Thus, in the
example makefile, we want the rule for `edit', which recompiles the
editor, to remain the default goal.
Since `clean' is not a prerequisite of `edit', this rule will not
run at all if we give the command `make' with no arguments. In order
to make the rule run, we have to type `make clean'. *Note How to Run
像这样的规则，不应当出现在makefile的起始处，因为我们不想让它被当作缺省终点而运行！
因此，在此makefile例子中，我们想让 edit 规则，也就是那个重新编译editor的规则，作为缺省的终点。
由于 clean 并不是 edit 的前提条件，如果我们运行 make而不带有参数，那么这个规则根本就不会运行。为了运行此规则，我们需要键入 make clean。
*Note How to Run make: Running
本文转自健哥的数据花园博客园博客，原文链接：http://www.cnblogs.com/gaojian/archive/2012/09/13/2683732.html，如需转载请自行联系原作者