By default, when make looks for the makefile, it tries the
following names, in order: GNUmakefile, makefile
and Makefile.
Normally you should call your makefile either makefile or
Makefile. (We recommend Makefile because it appears
prominently near the beginning of a directory listing, right near other
important files such as README.) The first name checked,
GNUmakefile, is not recommended for most makefiles. You should
use this name if you have a makefile that is specific to GNU
make, and will not be understood by other versions of
make. Other make programs look for makefile and
Makefile, but not GNUmakefile.
If make finds none of these names, it does not use any makefile.
Then you must specify a goal with a command argument, and make
will attempt to figure out how to remake it using only its built-in
implicit rules. See Using Implicit Rules.
If you want to use a nonstandard name for your makefile, you can specify
the makefile name with the ‘-f’ or ‘--file’ option. The
arguments ‘-f name’ or ‘--file=name’ tell
make to read the file name as the makefile. If you use
more than one ‘-f’ or ‘--file’ option, you can specify several
makefiles. All the makefiles are effectively concatenated in the order
specified. The default makefile names GNUmakefile,
makefile and Makefile are not checked automatically if you
specify ‘-f’ or ‘--file’.