Question

A common type of makefile has a line like this:

OBJS=something.o other.o third.o progname.o

progname: $(OBJS)

Then you would run make progname. But GNU Make can also generate the list of o-files itself from all the c-files it sees in the current directory. How is this done?

Basically, I want to be able to add C files to the directory without having to change the makefile.

^{(Is it for instance through some shell-magic, or is there is a built-in function for this?)}

Answer 1

To view all the defined rules (include the implicit ones), issue make -p.

However the fact that make knows how to generate object files from source files, does not mean that it should do this. Make will try to do the bare minimum in order to satisfy the target you ask it to build.

If you want make to compile all the sources into object in the current directory you will need a rule that will depend on all the objects, e.g.:

all: $(patsubst %.c,%.o,$(wildcard *.c))