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Unit 4: Installing Software

compile software directly from source code – download the source code which comes in a tarball, Notes
unzip it and then compile it.
In fact, this is the way source packages were distributed in the old days, and you might still have
to go by this route in some cases. However, to most people out there, compiling from source still
feels like voodoo. Here is a quick guide to all that you need to know about compiling from source
and what goes behind the scenes, without leaving anything to chance.

Unpacking

Command to use: [tar xvzf mypackage.tar.gz] or [tar xvjf mypackage.tar.bz2]
This is the first thing to be done when you download the software. All the source files, associated
libraries and documentation are distributed as compressed archives called tarballs. They are
compressed using either gzip or bzip2, and hence the different extensions and the slightly
differing switches used in the command.
After unpacking, a directory will be created with the name of the package in the destination
folder. Change the directory using cd mypackage and then use ls to explore the directory tree.
Make sure to read the readme, install and other documentation. Some packages might need some
additional libraries or might suffer from dependency issues, so it makes sense to know what’s
needed.

Configuring

Command to use: ./configure
After you have unpacked the tarball and have also solved any dependency issues by installing
required libraries it’s time to go to the next step: configuration. You have to run the command while
inside the installed package directory. This command does not change anything substantially. It
basically does a house-keeping job, checking whether all the required resources in the form of
system libraries are present and then assigning values for system dependent variables. Various
switches can be used along with the ./configure command to change the behaviour of the
program.

Example: Appending -quiet would stop printing the checking… messages during the
configure process.
If you know what you are doing you can use -no-create to inspect the output files before they are
created. Using -prefix=mydirectory you can change the path where the Makefile will be created.

After the ./configure command has run – during which you will see a bunch of messages scrolling
up the screen in rapid fire sequence – a Makefile will be created. This Makefile is then used to
build the binary which then needs to be installed.

Building

Command to use: make

The make command uses the Makefile to create installable binaries. Binaries are the Unix
equivalent of executables, or .exe files. The make command is time consuming and results in
a whole bunch of messages scrolling across your screen. This part is going to take a lot of time,
depending on the package being compiled as well as the system configuration. There will be
another bunch of messages scrolling across the screen, sometimes with warnings about some
resource being absent. If all is okay, it will display the command prompt. If however, there is
some problem it prompts you with appropriate status messages.

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