The make utility automatically determines which pieces of a large program need to be recompiled, 并且发出命令来重编译它们。
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
足以执行全部必要的重编译。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, 它都会执行data base中对应的recipe。
You can provide command line arguments to make to control which files should be recompiled, or how. 详见第九节：如何运行make