glfs/introduction/important/position.xml
Randy McMurchy 6732c09460 Updated all the XML files (and the one stylesheet) to use the 4.5 version of DocBook XML DTD
git-svn-id: svn://svn.linuxfromscratch.org/BLFS/trunk/BOOK@6716 af4574ff-66df-0310-9fd7-8a98e5e911e0
2007-04-04 19:42:53 +00:00

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XML

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!ENTITY % general-entities SYSTEM "../../general.ent">
%general-entities;
]>
<sect1 id="position">
<?dbhtml filename="position.html"?>
<sect1info>
<othername>$LastChangedBy$</othername>
<date>$Date$</date>
</sect1info>
<title>The /usr Versus /usr/local Debate</title>
<para><emphasis>Should I install XXX in <filename>/usr</filename> or
<filename>/usr/local</filename>?</emphasis></para>
<para>This is a question without an obvious answer for an
LFS based system.</para>
<para>In traditional Unix systems,
<filename class='directory'>/usr</filename> usually contains files that come
with the system distribution, and the
<filename class='directory'>/usr/local</filename> tree is free for the local
administrator to manage. The only really hard and fast rule is that Unix
distributions should not touch
<filename class='directory'>/usr/local</filename>, except perhaps to create
the basic directories within it.</para>
<para>With Linux distributions like Red Hat, Debian, etc., a possible rule is
that <filename class='directory'>/usr</filename> is managed by the
distribution's package system and
<filename class='directory'>/usr/local</filename> is not. This way the
package manager's database knows about every file within
<filename class='directory'>/usr</filename>.</para>
<para>LFS users build their own system and so deciding where
the system ends and local files begin is not straightforward. So the choice
should be made in order to make things easier to administer. There are
several reasons for dividing files between
<filename class='directory'>/usr</filename> and
<filename class='directory'>/usr/local</filename>.</para>
<itemizedlist>
<listitem>
<para>On a network of several machines all running LFS, or mixed LFS and
other Linux distributions,
<filename class='directory'>/usr/local</filename> could be used to hold
packages that are common between all the computers in the network. It can
be NFS mounted or mirrored from a single server. Here local indicates
local to the site.</para>
</listitem>
<listitem>
<para>On a network of several computers all running an identical
LFS system, <filename class='directory'>/usr/local</filename> could hold
packages that are different between the machines. In this case local
refers to the individual computers.</para>
</listitem>
<listitem>
<para>Even on a single computer,
<filename class='directory'>/usr/local</filename> can be useful if you
have several distributions installed simultaneously, and want
a place to put packages that will be the same on all of them.</para>
</listitem>
<listitem>
<para>Or you might regularly rebuild your LFS, but
want a place to put files that you don't want to rebuild each time. This
way you can wipe the LFS file system and start from a clean
partition every time without losing everything.</para>
</listitem>
</itemizedlist>
<para>Some people ask why not use your own directory tree, e.g.,
<filename class='directory'>/usr/site</filename>, rather than
<filename class='directory'>/usr/local</filename>?</para>
<para>There is nothing stopping you, many sites do make their own trees,
however it makes installing new software more difficult. Automatic installers
often look for dependencies in
<filename class='directory'>/usr</filename> and
<filename class='directory'>/usr/local</filename>, and if the file it is
looking for is in <filename class='directory'>/usr/site</filename> instead,
the installer will probably fail unless you specifically tell it where to
look.</para>
<para><emphasis>What is the BLFS position on this?</emphasis></para>
<para>All of the BLFS instructions install programs in
<filename class='directory'>/usr</filename> with optional instructions to
install into <filename class='directory'>/opt</filename> for some specific
packages.</para>
</sect1>