<listitem>

	  <para><command>make check-old</command></para>

	  <para>When new files, directories or libraries (or new versions

	of existing files) are installed, the old versions might become

	obsolete. This command will show all obsolete files.

	    </para>

	</listitem>

	<listitem>

	  <para><command>make delete-old</command></para>

	  <para>Deleting obsolete files is recommended.

	In some cases deleting obsolete files is required

	to avoid various compilation problems. More on that below.

	    </para>

    <warning>

      <title>Warning</title>

      <para>Before deleting old versions of shared libraries, you need

	to make sure that no ports depend on those. Any port that

	does depend on old versions of shared libraries will have to be

	rebuilt prior to your deleting old versions. Otherwise,

	you might find that some ports don't work anymore.

	</para>

    </warning>

	</listitem>

    <sect2 id="delete-old">

      <title>Deleting obsolete files, directories, libraries</title>

      <para>Now you need to make sure there are no obsolete

	files which might cause various compilation problems with

	the base operating system, the kernel and ports.

	</para>

	<para>Do</para>

      <screen>&prompt.root; <userinput>cd /usr/src</userinput></screen>

	<para>and start with</para>

      <screen>&prompt.root; <userinput>make check-old</userinput></screen>

	<para>This will check for old files, directories and shared

	libraries. If any obsolete files are found, you can

	then do</para>

      <screen>&prompt.root; <userinput>make delete-old</userinput></screen>

	<tip>

                <para>Have a look at <filename>/usr/src/Makefile</filename>

		for more targets of interest, e.g.</para>

			<screen>

# check-old           - List obsolete directories/files/libraries.

# check-old-dirs      - List obsolete directories.

# check-old-files     - List obsolete files.

# check-old-libs      - List obsolete libraries.

# delete-old          - Delete obsolete directories/files/libraries.

# delete-old-dirs     - Delete obsolete directories.

# delete-old-files    - Delete obsolete files.

# delete-old-libs     - Delete obsolete libraries.

			</screen>

		<para>More detailed comments are provided for each target in

			the makefile itself.</para>

	</tip>

	<para>You will be prompted before deleting each file or

	directory. Be particularly careful when offered to

	delete a shared library. If there are ports which

	depend on it, these ports will not run if you choose

	to delete it.

	</para>

	<para> You might want to use

  <ulink url="http://www.freshports.org/sysutils/libchk/">libchk</ulink> 

	port to find out which ports, if any, depend on an old

	version of shared library. You are advised to rebuild

	all such ports, to use the new version of shared

	libraries. Then, if you are satisfied that there are

	no more ports which depend on the old version  

	of shared library, you can delete it.

	</para>

	<para>If you don't delete obsolete shared libraries, you might

	end up getting messages like this:

	</para>

	<screen>

/usr/bin/ld: warning: libz.so.4, needed by /usr/local/lib/libtiff.so, may conflict with libz.so.5

/usr/bin/ld: warning: librpcsvc.so.4, needed by /usr/local/lib/libXext.so, may conflict with librpcsvc.so.5

	</screen>

	<para>In both examples linker is complaining about ports

	compiled with old versions of shared libraries, while the

	new versions are available. Conflicts are possible if

	these ports depend on other ports which are built with

	the new version of the same shared library.</para>

	<para>Fortunately the solution is very simple. First

	find which port installed the file in question:</para>

	<screen>

&prompt.root; <userinput>pkg_info -W  /usr/local/lib/libtiff.so</userinput>

/usr/local/lib/libtiff.so was installed by package tiff-3.9.4

&prompt.root; <userinput>pkg_info -W /usr/local/lib/libXext.so</userinput>

/usr/local/lib/libXext.so was installed by package libXext-1.1.1,1

	</screen>

	<para>Then just rebuild the ports in question.</para>

    </sect2>