Managing file interactions with make

Managing file interactions with make

The trend toward increased modularity of programs means that a project may have to cope with a large assortment of individual files. There may also be a wide range of generation procedures needed to turn the assortment of individual files into the final executable product.

make provides a method for maintaining up-to-date versions of programs that consist of a number of files that may be generated in a variety of ways.

An individual programmer can easily forget

file-to-file dependencies
files that were modified and the impact that has on other files
the exact sequence of operations needed to generate a new version of the program

make keeps track of the commands that create files and the relationship between files. Whenever a change is made in any of the files that make up a program, the make command creates the finished program by recompiling only those portions directly or indirectly affected by the change. The relationships between files and the processes that generate files are specified by the user in a description file.

The basic operation of make is to

find the target in the description file
ensure that all the files on which the target depends, the files needed to generate the target, exist and are up to date
(re)create the target file if any of the generators have been modified more recently than the target

The description file that holds the information on interfile dependencies and command sequences is conventionally called makefile, Makefile, s.makefile, or s.Makefile. If this naming convention is followed, the simple command make is usually sufficient to regenerate the target regardless of the number of files edited since the last make. In most cases, the description file is not difficult to write and changes infrequently. Even if only a single file has been edited, rather than entering all the commands to regenerate the target, entering the make command ensures that the regeneration is done in the prescribed way.