2 Application

The make program has many applications. One of the most common applications of make is to update an executable so it is consistent with updated source files.

Consider a project that has 3 course files, a.c, b.c and c.c. In order to create an executable, the following commands need to be issued:

gcc -c a.c
gcc -c b.c
gcc -c c.c
gcc -o abc a.o b.o c.o

Of course, one can also execute the following command instead:

gcc -o abc a.c b.c c.c

However, the one-command version may recompile source files that have not been updated. With three small files, the penalty is minimal. However, for a large scale project, the one-command method is unacceptable.

If we update b.c, the minimum compilation and linking can be done as follows:

gcc -c b.c
gcc -o abc a.o b.o c.o

What if we forget to recompile b.c? We'll be running the old version of the program! This can lead to unnecessary time for debugging and much frustration.

It'd be nice if we can somehow have a tool to figure out what needs to be recompiled and relinked at a minimum level. Well, that's make!