Make-A Program for Maintaining Computer Programs

In a programming project, it is easy to lose track of which files need to be reprocessed or recompiled after a change is made in some part of the source. Make provides a simple mechanism for maintaining up-to-date versions of programs that result from many operations on a number of files. It is possible to tell Make the sequence of commands that create certain files, and the list of files that require other files to be current before the operations can be done. Whenever a change is made in any part of the program, the Make command will create the proper files simply, correctly, and with a minimum amount of effort. The basic operation of Make is to find the name of a needed target in the description, ensure that all of the files on which it depends exist and are up to date, and then create the target if it has not been modified since its generators were. The description file really defines the graph of dependencies; Make does a depth-first search of this graph to determine what work is really necessary. Make also provides a simple macro substitution facility and the ability to encapsulate commands in a single file for convenient administration.