Makefiles

A makefile is a file used by the Unix make utility. Basically, the make utility will execute the script in the makefile. This gives you the ability to build complex software with dependencies. A simple makefile for your first homework assignment is depicted below. You will need to type this in and put it in your public_html/111/lab1 directory. From now on, you can modify this file to compile your labs. I will go over how to create this file in lab and also in class at a later date. For your later assignments, we will be creating a bit more complex makefile.

This file must be named either Makefile or makefile.

It is executed with the make command. Just type the word make while in the public_html/111/lab1 directory. Remember: cd ~/public_html/111/lab1

The make command will execute the first target name it finds, which is HelloWorld.class. See below for an explanation of each line. If at anytime you want to force a new compile of your source files, just delete the file HelloWorld.class.

#This is a comment.  It is ignored by the make utility.
CC=javac -d
DOC=javadoc -private -d _docs

HelloWorld.class : HelloWorld.java
[TAB]$(CC) HelloWorld.java 2> errorlog
[TAB]cp HelloWorld.java HelloWorld.txt

docs : HelloWorld.java
[TAB]$(DOC) HelloWorld.java

Note that the indented lines have TAB characters (do not type the phrase [TAB], just hit the TAB key!). There is no space after the TAB. This is a requirement of the makefile format.

Line 1	Comment, completely ignored by `make`.
Line 2	Define a macro named `CC` to run the `javac` command.
Line 3	Define a macro named `DOC` to run the `javadoc` command.
Line 4	Separate the sections with a blank line.
Line 5	`HelloWorld.class` is a target. If `HelloWorld.java` has not been modified since the last `HelloWorld.class` file was created, make will exit here. If it has changed since the last good compile, make will continue processing this makefile.
Line 6	Run the `CC` macro to compile the `HelloWorld.java` file and send any error output to a file named `errorlog`. If there is no error output, the file `errorlog` will be empty. If there is an error, the make utility will stop processing here and the errorlog file will contain the error output of the compiler. The `2>` tells the Unix shell to send error output to the file indicated (`errorlog`).
Line 7	If the compile is successful this line will copy the `HelloWorld.java` file to `HelloWorld.txt` as a backup.
Line 8	Separating blank line.
Line 9	`docs` is a target. It depends on the `HelloWorld.java` file existing. Typing `make docs` will cause this target to be processed. This target cannot have the same name as the _docs directory. This is why I chose to have the _docs directory name begin with an _ character.
Line 10	Run the `DOC` macro to create javadoc web pages for the lab. These will be stored in the _docs directory. (`public_html/111/lab1/_docs`).

To compile your program just type make

To create javadocs, just type make docs

Always make docs as the last step before turning in a project.

For more on makefiles, see GNU make, The Makefile or makefile Conventions