Over and over I have heard people say that you just use the usual configure, make, make install sequence to get a program running. Unfortunately, most people using computers today have never used a compiler or written a line of program code. With the advent of graphical user interfaces and applications builders, there are lots of serious programmers who have never done this.
What you have are three steps, each of which will use a whole host of programs to get a new program up and running. Running configure is relatively new compared with the use of make. But, each step has a very distinct purpose. I am going to explain the second and third steps first, then come back to configure.
The make utility is embedded in UNIX history. It is designed to decrease a programmer's need to remember things. I guess that is actually the nice way of saying it decreases a programmer's need to document. In any case, the idea is that if you establish a set of rules to create a program in a format make understands, you don't have to remember them again.
To make this even easier, the make utility has a set of built-in rules so you only need to tell it what new things it needs to know to build your particular utility. For example, if you typed in make love, make would first look for some new rules from you. If you didn't supply it any then it would look at its built-in rules. One of those built-in rules tells make that it can run the linker (ld) on a program name ending in .o to produce the executable program.
So, make would look for a file named love.o. But, it wouldn't stop there. Even if it found the .o file, it has some other rules that tell it to make sure the .o file is up to date. In other words, newer than the source program. The most common source program on Linux systems is written in C and its file name ends in .c.
If make finds the .c file (love.c in our example) as well as the .o file, it would check their timestamps to make sure the .o was newer. If it was not newer or did not exist, it would use another built-in rule to build a new .o from the .c (using the C compiler). This same type of situation exists for other programming languages. The end result, in any case, is that when make is done, assuming it can find the right pieces, the executable program will be built and up to date.
The old UNIX joke, by the way, is what early versions of make said when it could not find the necessary files. In the example above, if there was no love.o, love.c or any other source format, the program would have said:
make: don't know how to make love. Stop.
Getting back to the task at hand, the default file for additional rules in Makefile in the current directory. If you have some source files for a program and there is a Makefile file there, take a look. It is just text. The lines that have a word followed by a colon are targets. That is, these are words you can type following the make command name to do various things. If you just type make with no target, the first target will be executed.
What you will likely see at the beginning of most Makefile files are what look like some assignment statements. That is, lines with a couple of fields with an equal sign between them. Surprise, that is what they are. They set internal variables in make. Common things to set are the location of the C compiler (yes, there is a default), version numbers of the program and such.
This now beings up back to configure. On different systems, the C compiler might be in a different place, you might be using ZSH instead of BASH as your shell, the program might need to know your host name, it might use a dbm library and need to know if the system had gdbm or ndbm and a whole bunch of other things. You used to do this configuring by editing Makefile. Another pain for the programmer and it also meant that any time you wanted to install software on a new system you needed to do a complete inventory of what was where.
As more and more software became available and more and more POSIX-compliant platforms appeared, this got harder and harder. This is where configure comes in. It is a shell script (generally written by GNU Autoconf) that goes up and looks for software and even tries various things to see what works. It then takes its instructions from Makefile.in and builds Makefile (and possibly some other files) that work on the current system.
Background work done, let me put the pieces together.
You run configure (you usually have to type ./configure as most people don't have the current directory in their search path). This builds a new Makefile.
Type make This builds the program. That is, make would be executed, it would look for the first target in Makefile and do what the instructions said. The expected end result would be to build an executable program.
Now, as root, type make install. This again invokes make, make finds the target install in Makefile and files the directions to install the program.
This is a very simplified explanation but, in most cases, this is what you need to know. With most programs, there will be a file named INSTALL that contains installation instructions that will fill you in on other considerations. For example, it is common to supply some options to the configure command to change the final location of the executable program. There are also other make targets such as clean that remove unneeded files after an install and, in some cases test which allows you to test the software between the make and make install steps.
Understanding software Installation (configure, make, make install)
This tutorial is aimed at those who have just started using Linux. Generally when users from the Windows background enter the Linux scene,they are totally stumped by the software installation method. They were used to the luxury of double clicking on a single file and getting their software installed. But now they have to type cryptic commands to do the same.
Though the installation instructions tell them what to do, they have no idea what those steps actually do. This article shall explain the basics of software installation. After reading this article you would feel more at home when installing your next software.
Generally beginners tend to search desperately for RPMs since installing RPMs is a real simple task. But this article doesn't talk about RPMs. It deals with the softwares that you generally get in the zipped formats as tarballs.
Details :
Generally you would get Linux software in the tarball format (.tgz) This file has to be uncompressed into any directory using tar command. In case you download a new tarball by the name game.tgz, then you would have to type the following command
$ tar xfvz game.tgz
This would create a directory within the current directory and unzip all the files within that new directory. Once this is complete the installation instructions ask you to execute the 3 (now famous) commands : configure, make & make install. Most of the users do this and successfully install their softwares. But most of the newbies have no idea what this really does. The rest of the article shall explain the meaning of these 3 commands
Each software comes with a few files which are solely for the purpose of installation sake. One of them is the configure script. The user has to run the following command at the prompt
$ ./configure
The above command makes the shell run the script named ' configure ' which exists in the current directory. The configure script basically consists of many lines which are used to check some details about the machine on which the software is going to be installed. This script checks for lots of dependencies on your system. For the particular software to work properly, it may be requiring a lot of things to be existing on your machine already. When you run the configure script you would see a lot of output on the screen , each being some sort of question and a respective yes/no as the reply. If any of the major requirements are missing on your system, the configure script would exit and you cannot proceed with the installation, until you get those required things.
The main job of the configure script is to create a ' Makefile ' . This is a very important file for the installation process. Depending on the results of the tests (checks) that the configure script performed it would write down the various steps that need to be taken (while compiling the software) in the file named Makefile.
If you get no errors and the configure script runs successfully (if there is any error the last few lines of the output would glaringly be stating the error) then you can proceed with the next command which is
$ make
' make ' is actually a utility which exists on almost all Unix systems. For make utility to work it requires a file named Makefile in the same directory in which you run make. As we have seen the configure script's main job was to create a file named Makefile to be used with make utility. (Sometimes the Makefile is named as makefile also)
make would use the directions present in the Makefile and proceed with the installation. The Makefile indicates the sequence, that Linux must follow to build various components / sub-programs of your software. The sequence depends on the way the software is designed as well as many other factors.
The Makefile actually has a lot of labels (sort of names for different sections). Hence depending on what needs to be done the control would be passed to the different sections within the Makefile Or it is possible that at the end of one of the section there is a command to go to some next section.
Basically the make utility compiles all your program code and creates the executables. For particular section of the program to complete might require some other part of the code already ready, this is what the Makefile does. It sets the sequence for the events so that your program does not complain about missing dependencies.
One of the labels present in the Makefile happens to be named ' install ' .
If make ran successfully then you are almost done with the installation. Only the last step remains which is
$ make install
As indicated before make uses the file named Makefile in the same directory. When you run make without any parameters, the instruction in the Makefile begin executing from the start and as per the rules defined within the Makefile (particular sections of the code may execute after one another..thats why labels are used..to jump from one section to another). But when you run make with install as the parameter, the make utility searches for a label named install within the Makefile, and executes only that section of the Makefile.
The install section happens to be only a part where the executables and other required files created during the last step (i.e. make) are copied into the required final directories on your machine. E.g. the executable that the user runs may be copied to the /usr/local/bin so that all users are able to run the software. Similarly all the other files are also copied to the standard directories in Linux. Remember that when you ran make, all the executables were created in the temporary directory where you had unzipped your original tarball. So when you run make install, these executables are copied to the final directories.
Thats it!Now the installation process must be clear to you. You surely will feel more at home when you begin your next software installation.
