make: Preparing
Preparing and Running Make
==========================
To prepare to use 'make', you must write a file called the "makefile"
that describes the relationships among files in your program and
provides commands for updating each file. In a program, typically, the
executable file is updated from object files, which are in turn made by
compiling source files.
Once a suitable makefile exists, each time you change some source
files, this simple shell command:
make
suffices to perform all necessary recompilations. The 'make' program
uses the makefile data base and the last-modification times of the files
to decide which of the files need to be updated. For each of those
files, it issues the recipes recorded in the data base.
You can provide command line arguments to 'make' to control which
files should be recompiled, or how. 
How to Run 'make' Running.
Info Catalog
make: Overview
make: Overview
make: Reading