The Null Suffix

Many programs consist of a single source file. make handles this case by the null suffix rule. To maintain the operating system program cat, a rule in the makefile of the following form is needed:

$(CC) -o $@ $(CFLAGS) $(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 operating 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:

Others can be added in the makefile by the user.