source: chapter02/install.xml@ cc107b1

<sect1 id="ch02-install">
<title>How to install the software</title>

<para>
Before you can actually start doing something with a package, you need
to unpack it first. Often the package files are tar'ed and
gzip'ed. (That can be determined by looking at the extension of the file.
Tar'ed and gzip'ed archives have a .tar.gz or .tgz extension, for
example.) I'm not going to write down every time how to ungzip and how 
to untar an archive. I will explain how to do that once, in this section. 
There is also the possibility that a .tar.bz2 file could be downloaded.
Such a file would be tar'ed and compressed with the bzip2 program. 
Bzip2 achieves a better compression than the more commonly used gzip does. 
In order to use bz2 archives, the bzip2 program needs to be installed. 
Most if not every distribution comes with this program, so chances are 
high it is already installed on the host system. If not, it's installed 
using the distribution's installation tool.
</para>

<para>
To start with, change to the $LFS/usr/src directory by running:
</para>

<blockquote><literallayout>

        <userinput>cd $LFS/usr/src</userinput>

</literallayout></blockquote>

<para>
If a file is tar'ed and gzip'ed, it is unpacked by
running either one of the following two commands, depending on the
filename:
</para>

<blockquote><literallayout>

        <userinput>tar xvzf filename.tar.gz</userinput>
        <userinput>tar xvzf filename.tgz</userinput>

</literallayout></blockquote>


<para>
If a file is tar'ed and bzip2'ed, it is unpacked by
running:
</para>

<blockquote><literallayout>

        <userinput>bzcat filename.tar.bz2 | tar xv</userinput>

</literallayout></blockquote>

<para>
Some tar programs (most of them nowadays but not all of them) are
slightly modified to be able to use bzip2 files directly using either
the I or the y tar parameter, which works the same as the z tar parameter
to handle gzip archives. The above construction works no matter how
your host system decided to patch bzip2.
</para>

<para>
If a file is just tar'ed, it is unpacked by running:
</para>

<blockquote><literallayout>

        <userinput>tar xvf filename.tar</userinput>

</literallayout></blockquote>

<para>
When the archive is unpacked, a new directory will be created under the
current directory (and this book assumes that the archives are unpacked
under the $LFS/usr/src directory). Please enter that new directory
before continuing with the installation instructions. Again, every time
this book is going to install a package, it's up to you to unpack the source
archive and cd into the newly created directory.
</para>

<para>
From time to time you will be dealing with single files such as patch
files. These files are generally gzip'ed or bzip2'ed. Before such files
can be used they need to be uncompressed first.
</para>

<para>
If a file is gzip'ed, it is unpacked by running:
</para>

<blockquote><literallayout>

        <userinput>gunzip filename.gz</userinput>

</literallayout></blockquote>

<para>
If a file is bzip2'ed, it is unpacked by running:
</para>

<blockquote><literallayout>

        <userinput>bunzip2 filename.bz2</userinput>

</literallayout></blockquote>

<para>
After a package is installed, two things can be done with it:
either the directory that contains the sources can be deleted,
or it can be kept. If it is kept, that's fine with me, but if the 
same package is needed again in a later chapter, the directory 
needs to be deleted first before using it again. If this is not done, 
you might end up in trouble because old settings will be used (settings 
that apply to the host system but which don't always apply to 
the LFS system). Doing a simple make clean or make distclean does not 
always guarantee a totally clean source tree.
</para>

<para>
There is one exception to that rule: don't remove the Linux kernel source
tree. A lot of programs need the kernel headers, so that's the only
directory that should not be removed, unless no software is to be compiled
anymore.
</para>

</sect1>