source: introduction/important/position.xml@ 5cd0959d

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<sect1 id="intro-important-position">
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<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
<acronym>LFS</acronym> based system.</para>

<para>In traditional Unix systems, <filename>/usr</filename> usually 
contains files that come with the system distribution, and the <filename>
/usr/local</filename> tree is free for the local administrator to add things 
to.  The only really hard and fast rule is that Unix distributions should not 
touch <filename>/usr/local</filename>, except perhaps for creating the basic 
directories within it.</para>

<para>With Linux distributions, like Red Hat, Debian etc. a possible rule is
that <filename>/usr</filename> is managed by the distribution's 
package system and <filename>/usr/local</filename> is not.  This way the 
package manager's database knows about every file within
<filename>/usr</filename>.</para>

<para><acronym>LFS</acronym> 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>/usr</filename> and
<filename>/usr/local</filename>.</para>

<itemizedlist>

<listitem><para>On a network of several machines all running <acronym>LFS</acronym>, 
or mixed <acronym>LFS</acronym> and other Linux distributions, 
<filename>/usr/local</filename> could be used to hold packages
that are common between all the computers in the network.  It can be
<acronym>NFS</acronym> 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 
<acronym>LFS</acronym> system <filename>/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>/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 <acronym>LFS</acronym>, but 
want a place to put files that you don't want to rebuild each time.  This way 
you can wipe the <acronym>LFS</acronym> 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>
/usr/site</filename>, rather than <filename>/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>/usr</filename> and
<filename>/usr/local</filename>, and if the file it is looking
for is in <filename>/usr/site</filename> instead, the installer will 
probably fail unless you specifically tell it where to look.</para>

<para><emphasis>What is the <acronym>BLFS</acronym> position on this?</emphasis>
</para>

<para>All of the <acronym>BLFS</acronym> instructions install programs in
<filename>/usr</filename> with optional instructions to install into
<filename>/opt</filename> for some specific packages.</para>

</sect1>