Concurrent File Modification

You must make sure that targets built concurrently do not attempt to modify the same files at the same time. This can happen in a variety of ways. If a new suffix rule is defined that must use a temporary file, the temporary file name must be different for each target. You can accomplish this by using the dynamic macros $@ or $*. For example, a .c.o rule that performs some modification of the .c file before compiling it might be defined as:

.c.o:
    awk -f modify.awk $*.c > $*.mod.c
    $(COMPILE.c) $*.mod.c -o $*.o
    $(RM) $*.mod.c