Managing file interactions with make

The null suffix

There are many programs that consist of a single source file. make handles this case by the null suffix rule. Thus, to maintain the SCO OpenServer system program cat, a rule in the makefile of the following form is needed:

   .c:
           $(CC) $(CFLAGS) -o $@ $< $(LDFLAGS)

In fact, this .c: rule is internally defined so no makefile is necessary at all. The user only needs to enter

   $ make cat dd echo date

(these are all SCO OpenServer system single-file programs) and all four C language source files are passed through the above shell command line associated with the .c: rule. The internally defined single suffix rules are

.c:
.c~:
.s:
.s~:

.sh:
.sh~:
.f:

.f~:
.C:
.C~:

Others may be added in the makefile by the user.