]> git.donarmstrong.com Git - debian/debian-policy.git/blobdiff - policy.sgml
Synchronized with patch 115 from Manojs tree
[debian/debian-policy.git] / policy.sgml
index c8537a4b275c666ef351c444e0092867b11f946a..b1c1018af0a515ebfd9b33364516cb0c4bd378d5 100644 (file)
@@ -86,9 +86,9 @@
          <tt>/usr/share/common-licenses/GPL</tt> in the Debian GNU/Linux
          distribution or on the World Wide Web at
          <url id="http://www.gnu.org/copyleft/gpl.html"
-              name="The GNU General Public Licence">. You can also obtain it by writing to the
-         Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-         Boston, MA 02111-1307, USA.
+              name="The GNU General Public Licence">. You can also
+         obtain it by writing to the Free Software Foundation, Inc.,
+         59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
        </p>
       </copyright>
     </titlepag>
                    interfaces not changing, and the package
                    management software authors need to ensure
                    compatibility with these interface
-                   definitions. (Control file and and changelog file
+                   definitions. (Control file and changelog file
                    formats are examples.)
                  </p>
                </item>
          <em>may</em>, and the adjectives <em>required</em>,
          <em>recommended</em> and <em>optional</em>, are used to
          distinguish the significance of the various guidelines in
-         this policy document. Packages that do not conform the the
+         this policy document. Packages that do not conform to the
          guidelines denoted by <em>must</em> (or <em>required</em>)
          will generally not be considered acceptable for the Debian
          distribution. Non-conformance with guidelines denoted by
        </p>
       </sect>
     </chapt>
+
     <chapt>
       <heading>The Debian Archive</heading>
       <p>
          <p>
            Every package must be accompanied by a verbatim copy of
            its copyright and distribution license in the file
-           <tt>/usr/share/doc/<em>&lt;package-name&gt;</em>/copyright</tt>
+           <tt>/usr/share/doc/<em>&lt;package&gt;</em>/copyright</tt>
            (see <ref id="copyrightfile"> for further details).
          </p>
          <p>
            <item>
              <p>
                These packages provide a reasonably small but not too
-               limited character-mode system.  This is what will
-               install by default if the user doesn't select anything
+               limited character-mode system.  This is what will be
+               installed by default if the user doesn't select anything
                else.  It doesn't include many large applications, but
                it does include Emacs (this is more of a piece of
                infrastructure than an application) and a reasonable
       <sect>
        <heading>Source packages</heading>
 
-       <sect1>
+       <sect1 id="standardsversion">
          <heading>Standards conformance</heading>
-          <sect id="standardsversion">
 
          <p>
            In the source package's <tt>Standards-Version</tt> control
        format.
       </p>
 
-      <sect><heading>Syntax of control files</heading>
+      <sect id="controlsyntax"><heading>Syntax of control files</heading>
 
        <p>
          A control file consists of one or more paragraphs of fields.
          ignored there; it is conventional to put a single space
          after the colon.  For example, a field might be:
          <example>
-           Package: libc6
+Package: libc6
          </example>
          the field name is <tt>Package</tt> and the field value
          <tt>libc6</tt>.
 
        <p>
          The architectures we build on and build for are determined
-         by <prgn>make</prgn> variables using
+         by <prgn>make</prgn> variables using the utility
          <prgn>dpkg-architecture</prgn>.  You can determine the
          Debian architecture and the GNU style architecture
          specification string for the build machine (the machine type
              Though there is nothing stopping an author who is also
              the Debian maintainer from using it for all their
              changes, it will have to be renamed if the Debian and
-             upstream maintainers become different
-             people.
+             upstream maintainers become different people.  In such a
+             case, however, it might be better to maintain the
+             package as a non-native package.
            </p>
          </footnote>.
        </p>
        <p>
          That format is a series of entries like this:
          <example>
-           <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
+<var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
 
-           * <var>change details</var>
-             <var>more change details</var>
-           * <var>even more change details</var>
+  * <var>change details</var>
+    <var>more change details</var>
+  * <var>even more change details</var>
 
          -- <var>maintainer name and email address</var>  <var>date</var>
+ -- <var>maintainer name and email address</var>  <var>date</var>
          </example>
        </p>
 
          <prgn>dpkg</prgn> changelog format (though there is
          currently only one useful <var>keyword</var>,
          <tt>urgency</tt>).
+         <footnote>
+           <p>
+             Usual urgency values are <tt>low</tt>, <tt>medium</tt>,
+             <tt>high</tt> and <tt>critical</tt>.  They have an
+             effect on how quickly a package will be considered for
+             inclusion into the <tt>testing</tt> distribution, and
+             give an indication of the importance of any fixes
+             included in this upload.
+           </p>
+         </footnote>
        </p>
 
        <p>
        </p>
 
        <p>
-         The maintainer name and email address need <em>not</em>
-         necessarily be those of the usual package maintainer.
-         They should be the details of the person doing
-         <em>this</em> version.  The information here will be
-         copied to the <tt>.changes</tt> file, and then later used
-         to send an acknowledgement when the upload has been
-         installed.
+         If this upload resolves bugs recorded in the Bug Tracking
+         System (BTS), they may be automatically closed on the
+         inclusion of this package into the Debian archive by
+         including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
+         in the change details.
+         <footnote>
+           <p>
+             To be precise, the string should match the following
+             Perl regular expression:
+             <tt>/closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i</tt>
+             Then all of the bug numbers listed will be closed by the
+             archive maintenance script (<prgn>katie</prgn>), or in
+             the case of an NMU, marked as fixed.
+           </p>
+         </footnote>
+       </p>
+
+       <p>
+         The maintainer name and email address used in the changelog
+         should be the details of the person uploading <em>this</em>
+         version.  They are <em>not</em> necessarily those of the
+         usual package maintainer.  The information here will be
+         copied to the <tt>Changed-By</tt> field in the
+         <tt>.changes</tt> file, and then later used to send an
+         acknowledgement when the upload has been installed.
        </p>
 
        <p>
            </p>
          </footnote>; it should include the time zone specified
          numerically, with the time zone name or abbreviation
-         optionally present as a comment.
+         optionally present as a comment in parentheses.
        </p>
 
        <p>
        <p>
          When <prgn>dpkg-gencontrol</prgn>,
          <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
-         generate control files they do variable substitutions on
-         their output just before writing it.  Variable
+         generate control files they perform variable substitutions
+         on their output just before writing it.  Variable
          substitutions have the form
          <tt>${<var>variable-name</var>}</tt>.  The optional file
-         <tt>debian/substvars</tt> contains variable substitutions
-         to be used; variables can also be set directly from
+         <tt>debian/substvars</tt> contains variable substitutions to
+         be used; variables can also be set directly from
          <tt>debian/rules</tt> using the <tt>-V</tt> option to the
-         source packaging commands, and certain predefined
-         variables are available.
+         source packaging commands, and certain predefined variables
+         are also available.
        </p>
 
        <p>
-         The is usually generated and modified dynamically by
-         <tt>debian/rules</tt> targets; in this case it must be
-         removed by the <prgn>clean</prgn> target.
+         The <tt>debian/substvars</tt> file is usually generated and
+         modified dynamically by <tt>debian/rules</tt> targets; in
+         this case it must be removed by the <prgn>clean</prgn>
+         target.
        </p>
 
        <p>
        </p>
 
        <p>
-         <prgn>dpkg-gencontrol</prgn> adds an entry to this file
-         for the <tt>.deb</tt> file that will be created by
-         <prgn>dpkg-deb</prgn> from the control file that it
-         generates, so for most packages all that needs to be done
-         with this file is to delete it in <prgn>clean</prgn>.
+         When <prgn>dpkg-gencontrol</prgn> is run for a binary
+         package, it adds an entry to <tt>debian/files</tt> for the
+         <tt>.deb</tt> file that will be created when <prgn>dpkg-deb
+         --build</prgn> is run for that binary package.  So for most
+         packages all that needs to be done with this file is to
+         delete it in the <prgn>clean</prgn> target.
        </p>
 
        <p>
              packages, but only when extracting
              them.
            </p>
-         </footnote>
-         <footnote>
            <p>
              Hard links may be permitted at some point in the
              future, but would require a fair amount of
        </p>
 
        <p>
-         These scripts should be the files <tt>preinst</tt>,
+         These scripts are the files <tt>preinst</tt>,
          <tt>postinst</tt>, <tt>prerm</tt> and <tt>postrm</tt> in the
          control area of the package.  They must be proper executable
-         files; if they are scripts (which is recommended) they must
+         files; if they are scripts (which is recommended), they must
          start with the usual <tt>#!</tt> convention.  They should be
          readable and executable by anyone, and not world-writable.
        </p>
          well.
        </p>
 
-       <p>
-         It is necessary for the error recovery procedures that the
-         scripts be idempotent: i.e., invoking the same script several
-         times in the same situation should do no harm.  If the first
-         call failed, or aborted half way through for some reason,
-         the second call should merely do the things that were left
-         undone the first time, if any, and exit with a success
-         status.
-       </p>
-
        <p>
          When a package is upgraded a combination of the scripts from
-         the old and new packages is called in amongst the other
-         steps of the upgrade procedure.  If your scripts are going
-         to be at all complicated you need to be aware of this, and
-         may need to check the arguments to your scripts.
+         the old and new packages is called during the upgrade
+         procedure.  If your scripts are going to be at all
+         complicated you need to be aware of this, and may need to
+         check the arguments to your scripts.
        </p>
 
        <p>
          <prgn>postrm</prgn> afterwards.
        </p>
 
-       <p> Programs called from maintainer scripts should not
-         normally have a path prepended to them. Before installation
-         is started the package management system checks to see if
-         the programs <prgn>ldconfig</prgn>,
+       <p>
+         Programs called from maintainer scripts should not normally
+         have a path prepended to them. Before installation is
+         started, the package management system checks to see if the
+         programs <prgn>ldconfig</prgn>,
          <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
          and <prgn>update-rc.d</prgn> can be found via the
          <tt>PATH</tt> environment variable. Those programs, and any
-         other program that one would expect to on the <tt>PATH</tt>,
-         should thus be invoked without an absolute
+         other program that one would expect to be on the
+         <tt>PATH</tt>, should thus be invoked without an absolute
          pathname. Maintainer scripts should also not reset the
-         <tt>PATH</tt>, though they might choose to modify it by pre-
-         or appending package-specific directories. These
+         <tt>PATH</tt>, though they might choose to modify it by
+         prepending or appending package-specific directories. These
          considerations really apply to all shell scripts.</p>
       </sect>
+
       <sect>
        <heading>Maintainer scripts Idempotency</heading>
 
        <p>
-         It is very important to make maintainer scripts
-         idempotent.
-         <footnote>
+         It is necessary for the error recovery procedures that the
+         scripts be idempotent.  This means that if it is run
+         successfully, and then it is called again, it doesn't bomb
+         out or cause any harm, but just ensures that everything is
+         the way it ought to be.  If the first call failed, or
+         aborted half way through for some reason, the second call
+         should merely do the things that were left undone the first
+         time, if any, and exit with a success status if everything
+         is OK.
+         <footnote> 
            <p>
-             That means that if it runs successfully or fails
-             and then you call it again it doesn't bomb out,
-             but just ensures that everything is the way it
-             ought to be.
+             This is so that if an error occurs, the user interrupts
+             <prgn>dpkg</prgn> or some other unforeseen circumstance
+             happens you don't leave the user with a badly-broken
+             package when <prgn>dpkg</prgn> attempts to repeat the
+             action.
            </p>
-         </footnote> This is so that if an error occurs, the
-         user interrupts <prgn>dpkg</prgn> or some other
-         unforeseen circumstance happens you don't leave the
-         user with a badly-broken package.
+         </footnote>
        </p>
       </sect>
+
       <sect>
        <heading>Controlling terminal for maintainer scripts</heading>
 
            </item>
            <item>
              <p><var>old-postinst</var> <tt>abort-upgrade</tt>
-               <var>new version</var></p>
+               <var>new-version</var></p>
            </item>
            <item>
              <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
          The procedure on installation/upgrade/overwrite/disappear
          (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
          stage of <tt>dpkg --install</tt>) is as follows.  In each
-         case if an error occurs the actions are, in general, run
-         backwards - this means that the maintainer scripts are run
-         with different arguments in reverse order.  These are the
-         `error unwind' calls listed below.
+         case, if a major error occurs (unless listed below) the
+         actions are, in general, run backwards - this means that the
+         maintainer scripts are run with different arguments in
+         reverse order.  These are the `error unwind' calls listed
+         below.
 
          <enumlist>
            <item>
                    <p>If a version of the package is already
                      installed, call
                      <example>
-                       <var>old-prerm</var> upgrade <var>new-version</var>
+<var>old-prerm</var> upgrade <var>new-version</var>
                      </example></p>
                  </item>
                  <item>
                      If the script runs but exits with a non-zero
                      exit status, <prgn>dpkg</prgn> will attempt:
                      <example>
-                       <var>new-prerm</var> failed-upgrade <var>old-version</var>
+<var>new-prerm</var> failed-upgrade <var>old-version</var>
                      </example>
                      Error unwind, for both the above cases:
                      <example>
-                       <var>old-postinst</var> abort-upgrade <var>new-version</var>
+<var>old-postinst</var> abort-upgrade <var>new-version</var>
                      </example>
                    </p>
                  </item>
                      package and <tt>--auto-deconfigure</tt> is
                      specified, call, for each such package:
                      <example>
-                       <var>deconfigured's-prerm</var> deconfigure \
-                       in-favour <var>package-being-installed</var> <var>version</var> \
-                       removing <var>conflicting-package</var> <var>version</var>
+<var>deconfigured's-prerm</var> deconfigure \
+  in-favour <var>package-being-installed</var> <var>version</var> \
+    removing <var>conflicting-package</var> <var>version</var>
                      </example>
                      Error unwind:
                      <example>
-                       <var>deconfigured's-postinst</var> abort-deconfigure \
-                       in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
-                       removing <var>conflicting-package</var> <var>version</var>
+<var>deconfigured's-postinst</var> abort-deconfigure \
+  in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
+    removing <var>conflicting-package</var> <var>version</var>
                      </example>
                      The deconfigured packages are marked as
                      requiring configuration, so that if
                  <item>
                    <p>To prepare for removal of the conflicting package, call:
                      <example>
-                       <var>conflictor's-prerm</var> remove in-favour <var>package</var> <var>new-version</var>
+<var>conflictor's-prerm</var> remove \
+  in-favour <var>package</var> <var>new-version</var>
                      </example>
                      Error unwind:
                      <example>
-                       <var>conflictor's-postinst</var> abort-remove \
-                       in-favour <var>package</var> <var>new-version</var>
+<var>conflictor's-postinst</var> abort-remove \
+  in-favour <var>package</var> <var>new-version</var>
                      </example>
                    </p>
                  </item>
                  <item>
                    <p>If the package is being upgraded, call:
                      <example>
-                       <var>new-preinst</var> upgrade <var>old-version</var>
+<var>new-preinst</var> upgrade <var>old-version</var>
                      </example></p>
                  </item>
                  <item>
                      files from a previous version installed (i.e., it
                      is in the `configuration files only' state):
                      <example>
-                       <var>new-preinst</var> install <var>old-version</var>
+<var>new-preinst</var> install <var>old-version</var>
                      </example></p>
 
                  <item>
                    <p>Otherwise (i.e., the package was completely purged):
                      <example>
-                       <var>new-preinst</var> install
+<var>new-preinst</var> install
                      </example>
-                     Error unwind versions, respectively:
+                     Error unwind actions, respectively:
                      <example>
-                       <var>new-postrm</var> abort-upgrade <var>old-version</var>
-                       <var>new-postrm</var> abort-install <var>old-version</var>
-                       <var>new-postrm</var> abort-install
+<var>new-postrm</var> abort-upgrade <var>old-version</var>
+<var>new-postrm</var> abort-install <var>old-version</var>
+<var>new-postrm</var> abort-install
                      </example>
                    </p>
                  </item>
                The new package's files are unpacked, overwriting any
                that may be on the system already, for example any
                from the old version of the same package or from
-               another package (backups of the old files are left
-               around, and if anything goes wrong the package
+               another package.  Backups of the old files are kept
+               temporarily, and if anything goes wrong the package
                management system will attempt to put them back as
-               part of the error unwind).
+               part of the error unwind.
              </p>
 
              <p>
                It is an error for a package to contains files which
                are on the system in another package, unless
                <tt>Replaces</tt> is used (see <ref id="replaces">).
-               Currently the <tt>--force-overwrite</tt> flag is
+               <!--
+               The following paragraph is not currently the case:
+               Currently the <tt>- - force-overwrite</tt> flag is
                enabled, downgrading it to a warning, but this may not
                always be the case.
+               -->
              </p>
 
              <p>
 
              <p>
                Packages which overwrite each other's files produce
-               behavior which though deterministic is hard for the
+               behavior which, though deterministic, is hard for the
                system administrator to understand.  It can easily
                lead to `missing' programs if, for example, a package
                is installed which overwrites a file from another
              </p>
 
              <p>
-               A directory will never be replaced by a symbolic links
+               A directory will never be replaced by a symbolic link
                to a directory or vice versa; instead, the existing
                state (symlink or not) will be left alone and
                <prgn>dpkg</prgn> will follow the symlink if there is
                  <item>
                    <p>If the package is being upgraded, call
                      <example>
-                       <var>old-postrm</var> upgrade <var>new-version</var>
+<var>old-postrm</var> upgrade <var>new-version</var>
                      </example></p>
                  </item>
                  <item>
                    <p>If this fails, <prgn>dpkg</prgn> will attempt:
                      <example>
-                       <var>new-postrm</var> failed-upgrade <var>old-version</var>
+<var>new-postrm</var> failed-upgrade <var>old-version</var>
                      </example>
                      Error unwind, for both cases:
                      <example>
-                       <var>old-preinst</var> abort-upgrade <var>new-version</var>
+<var>old-preinst</var> abort-upgrade <var>new-version</var>
                      </example>
                    </p>
                  </item>
              <p>Any packages all of whose files have been overwritten during the
                installation, and which aren't required for
                dependencies, are considered to have been removed.
-               For each such package,
+               For each such package
                <enumlist>
                  <item>
                    <p><prgn>dpkg</prgn> calls:
                      <example>
-                       <var>disappearer's-postrm</var> disappear \
-                       <var>overwriter</var> <var>overwriter-version</var>
+<var>disappearer's-postrm</var> disappear \
+  <var>overwriter</var> <var>overwriter-version</var>
                      </example>
                    </p>
                  </item>
            <item>
              <p>
                The new package's status is now sane, and recorded as
-               `unpacked'.  Here is another point of no return - if
-               the conflicting package's removal fails we do not
-               unwind the rest of the installation; the conflicting
-               package is left in a half-removed limbo.
+               `unpacked'.
+             </p>
+
+             <p>
+               Here is another point of no return - if the
+               conflicting package's removal fails we do not unwind
+               the rest of the installation; the conflicting package
+               is left in a half-removed limbo.
              </p>
            </item>
+
            <item>
              <p>
                If there was a conflicting package we go and do the
        <p>
          When we configure a package (this happens with <tt>dpkg
            --install</tt>, or with <tt>--configure</tt>), we first
-         update the conffiles and then call:
+         update any <tt>conffile</tt>s and then call:
          <example>
-           <var>postinst</var> configure <var>most-recently-configured-version</var>
+<var>postinst</var> configure <var>most-recently-configured-version</var>
          </example>
        </p>
 
            <item>
              <p>
                <example>
-                 <var>prerm</var> remove
+<var>prerm</var> remove
                </example>
              </p>
            </item>
            <item>
              <p>
-               The package's files are removed (except conffiles).
+               The package's files are removed (except <tt>conffile</tt>s).
              </p>
            </item>
            <item>
-             <p><example>
-                 <var>postrm</var> remove
-               </example></p>
+             <p>
+               <example>
+<var>postrm</var> remove
+               </example>
+             </p>
            </item>
            <item>
-             <p>All the maintainer scripts except the postrm are removed.
+             <p>
+               All the maintainer scripts except the <tt>postrm</tt>
+               are removed.
              </p>
 
              <p>
                If we aren't purging the package we stop here.  Note
-               that packages which have no postrm and no conffiles
-               are automatically purged when removed, as there is no
-               difference except for the <prgn>dpkg</prgn>
-               status.</p>
+               that packages which have no <tt>postrm</tt> and no
+               <tt>conffile</tt>s are automatically purged when
+               removed, as there is no difference except for the
+               <prgn>dpkg</prgn> status.</p>
            </item>
            <item>
              <p>
                <tt>.dpkg-{old,new,tmp}</tt>, etc.) are removed.</p>
            </item>
            <item>
-             <p><example>
-                 <var>postrm</var> purge
-               </example></p>
+             <p>
+               <example>
+<var>postrm</var> purge
+               </example>
+             </p>
            </item>
            <item>
              <p>The package's file list is removed.</p>
            </item>
          </enumlist>
          No attempt is made to unwind after errors during
-         removal.</p>
+         removal.
+       </p>
       </sect>
     </chapt>
 
 
     <chapt id="relationships"><heading>Declaring relationships between
-       packages      </heading>
+       packages</heading>
 
       <p>
        Packages can declare in their control file that they have
       </p>
 
       <p>
-       This is done using the <tt>Depends</tt>, <tt>Recommends</tt>,
-       <tt>Suggests</tt>, <tt>Enhances</tt>, <tt>Conflicts</tt>,
-       <tt>Provides</tt> and <tt>Replaces</tt> control file fields.
+       This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
+       <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
+       <tt>Conflicts</tt>, <tt>Provides</tt> and <tt>Replaces</tt>
+       control file fields.
       </p>
 
       <p>
 
       <p>
         This is done using the <tt>Build-Depends</tt>,
-        <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt>, and
+        <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
         <tt>Build-Conflicts-Indep</tt> control file fields.
       </p>
 
           control file fields of the package, which declare
           dependencies on other packages, the package names listed may
           also include lists of alternative package names, separated
-          by vertical bar symbols <tt>|</tt> (pipe symbols).  In such
-          a case, the presence of any one of the alternative packages
-          is installed, that part of the dependency is considered to
-          be satisfied.
+          by vertical bar (pipe) symbols <tt>|</tt>.  In such a case,
+          if any one of the alternative packages is installed, that
+          part of the dependency is considered to be satisfied.
        </p>
 
        <p>
-         All the fields except <tt>Provides</tt> may restrict their
-         applicability to particular versions of each named package.
-         This is done in parentheses after each individual package
-         name; the parentheses should contain a relation from the
-         list below followed by a version number, in the format
+         All of the fields except for <tt>Provides</tt> may restrict
+         their applicability to particular versions of each named
+         package.  This is done in parentheses after each individual
+         package name; the parentheses should contain a relation from
+         the list below followed by a version number, in the format
          described in <ref id="versions">.
        </p>
 
          The relations allowed are <tt>&lt;&lt;</tt>, <tt>&lt;=</tt>,
          <tt>=</tt>, <tt>&gt;=</tt> and <tt>&gt;&gt;</tt> for
          strictly earlier, earlier or equal, exactly equal, later or
-         equal and strictly later, respectively.  The forms
-         <tt>&lt;</tt> and <tt>&gt;</tt> were used to mean
+         equal and strictly later, respectively.  The deprecated
+         forms <tt>&lt;</tt> and <tt>&gt;</tt> were used to mean
          earlier/later or equal, rather than strictly earlier/later,
          so they should not appear in new packages (though
          <prgn>dpkg</prgn> still supports them).
 
        <p>
          Whitespace may appear at any point in the version
-         specification, and must appear where it's necessary to
+         specification subject to the rules in <ref
+         id="controlsyntax">, and must appear where it's necessary to
          disambiguate; it is not otherwise significant.  For
          consistency and in case of future changes to
          <prgn>dpkg</prgn> it is recommended that a single space be
          used after a version relationship and before a version
-         number; it is usual also to put a single space after each
-         comma, on either side of each vertical bar, and before each
-         open parenthesis.
+         number; it is also conventional to put a single space after
+         each comma, on either side of each vertical bar, and before
+         each open parenthesis.
        </p>
 
        <p>
-         For example:
+         For example, a list of dependencies might appear as:
          <example>
-           Package: metamail
-           Version: 2.7-3
-           Depends: libc5 (>= 5.2.18-4), mime-support, csh | tcsh
+Package: mutt
+Version: 1.3.17-1
+Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
          </example>
        </p>
 
          (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
          <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
          may be restricted to a certain set of architectures.  This
-         is done in brackets after each individual package name and
+         is indicated in brackets after each individual package name and
          the optional version specification.  The brackets enclose a
          list of Debian architecture names separated by whitespace.
          Exclamation marks may be prepended to each of the names.
        <p>
          For example:
          <example>
-           Source: glibc
-           Build-Depends-Indep: texinfo
-           Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
-           hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
+Source: glibc
+Build-Depends-Indep: texinfo
+Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
+hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
          </example>
        </p>
       </sect>
        </p>
 
        <p>
-         All but <tt>Pre-Depends</tt> and <tt>Conflicts</tt>
-         (discussed below) take effect <em>only</em> when a package
-         is to be configured.  They do not prevent a package being on
-         the system in an unconfigured state while its dependencies
-         are unsatisfied, and it is possible to replace a package
-         whose dependencies are satisfied and which is properly
-         installed with a different version whose dependencies are
-         not and cannot be satisfied; when this is done the depending
-         package will be left unconfigured (since attempts to
-         configure it will give errors) and will not function
-         properly.
+         A <tt>Depends</tt> field takes effect <em>only</em> when a
+         package is to be configured.  It does not prevent a package
+         being on the system in an unconfigured state while its
+         dependencies are unsatisfied, and it is possible to replace
+         a package whose dependencies are satisfied and which is
+         properly installed with a different version whose
+         dependencies are not and cannot be satisfied; when this is
+         done the depending package will be left unconfigured (since
+         attempts to configure it will give errors) and will not
+         function properly.  If it is necessary, a
+         <tt>Pre-Depends</tt> field can be used, which has a partial
+         effect even when a package is being unpacked, as explained
+         in detail below.  (The other three dependency fields,
+         <tt>Recommends</tt>, <tt>Suggests</tt> and
+         <tt>Enhances</tt>, are only used by the various front-ends
+         to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
        </p>
 
        <p>
        </p>
 
        <p>
-         Thus <tt>Depends</tt> allows package maintainers to impose
-         an order in which packages should be configured.
+         The <tt>Depends</tt> field thus allows package maintainers
+         to impose an order in which packages should be configured.
+       </p>
+
+       <p>
+         The meaning of the five dependency fields is as follows:
          <taglist>
            <tag><tt>Depends</tt></tag>
            <item>
 
-             <p>This declares an absolute dependency.
+             <p>
+               This declares an absolute dependency.  A package will
+               not be configured unless all of the packages listed in
+               its <tt>Depends</tt> field have been correctly
+               configured.
              </p>
 
              <p>
                The <tt>Depends</tt> field should be used if the
                depended-on package is required for the depending
                package to provide a significant amount of
-               functionality.</p>
+               functionality.
+             </p>
+             <p>
+               The <tt>Depends</tt> field should also be used if the
+               <prgn>postinst</prgn>, <prgn>prerm</prgn> or
+               <prgn>postrm</prgn> scripts require the package to be
+               present in order to run.  Note, however, that the
+               <prgn>postrm</prgn> cannot rely on any non-essential
+               packages to be present during the <tt>purge</tt>
+               phase.
            </item>
 
            <tag><tt>Recommends</tt></tag>
                also forces <prgn>dpkg</prgn> to complete installation
                of the packages named before even starting the
                installation of the package which declares the
-               Pre-dependency.
+               pre-dependency, as follows:
              </p>
 
              <p>
-               <tt>Pre-Depends</tt> should be used sparingly,
-               preferably only by packages whose premature upgrade or
-               installation would hamper the ability of the system to
-               continue with any upgrade that might be in progress.
+               When a package declaring a pre-dependency is about to
+               be <em>unpacked</em> the pre-dependency can be
+               satisfied if the depended-on package is either fully
+               configured, <em>or even if</em> the depended-on
+               package(s) are only unpacked or half-configured,
+               provided that they have been configured correctly at
+               some point in the past (and not removed or partially
+               removed since).  In this case, both the
+               previously-configured and currently unpacked or
+               half-configured versions must satisfy any version
+               clause in the <tt>Pre-Depends</tt> field.
              </p>
 
              <p>
-               When the package declaring it is being configured, a
-               <tt>Pre-Dependency</tt> will be considered satisfied
-               only if the depending package has been correctly
-               configured, just as if an ordinary <tt>Depends</tt>
-               had been used.
+               When the package declaring a pre-dependency is about
+               to be <em>configured</em>, the pre-dependency will be
+               treated as a normal <tt>Depends</tt>, that is, it will
+               be considered satisfied only if the depended-on
+               package has been correctly configured.
              </p>
 
              <p>
-               However, when a package declaring a Pre-dependency is
-               being unpacked the predependency can be satisfied even
-               if the depended-on package(s) are only unpacked or
-               half-configured, provided that they have been
-               configured correctly at some point in the past (and
-               not removed or partially removed since).  In this case
-               both the previously-configured and currently unpacked
-               or half-configured versions must satisfy any version
-               clause in the <tt>Pre-Depends</tt> field.
+               <tt>Pre-Depends</tt> should be used sparingly,
+               preferably only by packages whose premature upgrade or
+               installation would hamper the ability of the system to
+               continue with any upgrade that might be in progress.
              </p>
+
+             <p>
+               <tt>Pre-Depends</tt> are also required if the
+               <prgn>preinst</prgn> script depends on the named
+               package.  It is best to avoid this situation if
+               possible.
            </item>
          </taglist>
        </p>
        </p>
 
 
-      <sect id="conflicts"><heading>Alternative binary packages -
-         <tt>Conflicts</tt> and <tt>Replaces</tt>
-       </heading>
+      <sect id="conflicts"><heading>Conflicting binary packages -
+          <tt>Conflicts</tt></heading>
 
        <p>
           When one binary package declares a conflict with another
-         <prgn>dpkg</prgn> will refuse to allow them to be installed
-         on the system at the same time.
+         using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
+         refuse to allow them to be installed on the system at the
+         same time.
        </p>
 
        <p>
          If one package is to be installed, the other must be removed
          first - if the package being installed is marked as
-         replacing (<ref id="replaces">) the one on the system, or
-         the one on the system is marked as deselected, or both
+         replacing (see <ref id="replaces">) the one on the system,
+         or the one on the system is marked as deselected, or both
          packages are marked <tt>Essential</tt>, then
          <prgn>dpkg</prgn> will automatically remove the package
          which is causing the conflict, otherwise it will halt the
-         installation of the new package with an error. This
-         mechanism specifically doesn't work when the installed
-         package is <tt>Essential</tt>, but the new package is not.
+         installation of the new package with an error.  This
+         mechanism is specifically designed to produce an error when
+         the installed package is <tt>Essential</tt>, but the new
+         package is not.
        </p>
 
-
        <p>
          A package will not cause a conflict merely because its
          configuration files are still installed; it must be at least
          prevent their installation, and allows a package to conflict
          with others providing a replacement for it.  You use this
          feature when you want the package in question to be the only
-         package providing something.
+         package providing some feature.
        </p>
 
        <p>
         <p>
          As well as the names of actual (`concrete') packages, the
          package relationship fields <tt>Depends</tt>,
+         <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
+         <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
          <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
-         <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Conflicts</tt>,
-         <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt> may
-         mention virtual packages.
+         <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
+         may mention `virtual packages'.
        </p>
 
        <p>
-         A virtual package is one which appears in the
+         A <em>virtual package</em> is one which appears in the
          <tt>Provides</tt> control file field of another package.
          The effect is as if the package(s) which provide a
          particular virtual package name had been listed by name
          packages which provide it.  This is so that, for example,
          supposing we have
          <example>
-           Package: vm
-           Depends: emacs
+Package: foo
+Depends: bar
          </example>
-         and someone else releases an xemacs package they can say
+         and someone else releases an enhanced version of the
+         <tt>bar</tt> package (for example, a non-US variant), they
+         can say:
          <example>
-           Package: xemacs
-           Provides: emacs
-         </example> and all will work in the interim (until a purely
-         virtual package name is decided on and the <tt>emacs</tt>
-         and <tt>vm</tt> packages are changed to use it).
+Package: bar-plus
+Provides: bar
+         </example>
+         and the <tt>bar-plus</tt> package will now also satisfy the
+         dependency for the <tt>foo</tt> package.
        </p>
 
        <p>
        </p>
 
        <p>
-         If you want to specify which of a set of real packages should be the
-         default to satisfy a particular dependency on a virtual package, you
-         should list the real package as an alternative before the virtual.
+         If you want to specify which of a set of real packages
+         should be the default to satisfy a particular dependency on
+         a virtual package, you should list the real package as an
+         alternative before the virtual one.
        </p>
       </sect>
 
 
-      <sect id="replaces"><heading><tt>Replaces</tt> - overwriting
-         files and replacing packages
-       </heading>
+      <sect id="replaces"><heading>Overwriting files and replacing
+         packages - <tt>Replaces</tt></heading>
 
        <p>
-         The <tt>Replaces</tt> control file field has two purposes,
-         which come into play in different situations.
+         The <tt>Replaces</tt> control file field has two distinct
+         purposes, which come into play in different situations.
        </p>
 
-       <p>
-         Virtual packages (<ref id="virtual">) are not considered
-         when looking at a <tt>Replaces</tt> field - the packages
-         declared as being replaced must be mentioned by their real
-         names.
-       </p>
-
-       <sect1><heading>Overwriting files in other packages
-         </heading>
+       <sect1><heading>Overwriting files in other packages</heading>
 
          <p>
            Firstly, as mentioned before, it is usually an error for a
            package to contain files which are on the system in
-           another package, though currently the
-           <tt>--force-overwrite</tt> flag is enabled by default,
-           downgrading the error to a warning,
+           another package.
          </p>
 
          <p>
-           If the overwriting package declares that it replaces the
-           one containing the file being overwritten then
-           <prgn>dpkg</prgn> will proceed, and replace the file from
-           the old package with that from the new.  The file will no
-           longer be listed as `owned' by the old package.
+           However, if the overwriting package declares that it
+           <tt>Replaces</tt> the one containing the file being
+           overwritten, then <prgn>dpkg</prgn> will replace the file
+           from the old package with that from the new.  The file
+           will no longer be listed as `owned' by the old package.
          </p>
 
          <p>
            If a package is completely replaced in this way, so that
            <prgn>dpkg</prgn> does not know of any files it still
-           contains, it is considered to have disappeared.  It will
+           contains, it is considered to have `disappeared'.  It will
            be marked as not wanted on the system (selected for
-           removal) and not installed.  Any conffiles details noted
-           in the package will be ignored, as they will have been
-           taken over by the replacing package(s).  The package's
-           <prgn>postrm</prgn> script will be run to allow the
-           package to do any final cleanup required.  See <ref
-                                                               id="mscriptsinstact">.
+           removal) and not installed.  Any <tt>conffile</tt>s
+           details noted for the package will be ignored, as they
+           will have been taken over by the overwriting package.  The
+           package's <prgn>postrm</prgn> script will be run with a
+           special argument to allow the package to do any final
+           cleanup required.  See <ref id="mscriptsinstact">.
          </p>
 
          <p>
-           In the future <prgn>dpkg</prgn> will discard files which
-           would overwrite those from an already installed package
-           which declares that it replaces the package being
-           installed.  This is so that you can install an older
-           version of a package without problems.
+           If an installed package, <tt>foo</tt> say, declares that
+           it replaces another, <tt>bar</tt>, and an attempt is made
+           to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
+           files in the <tt>bar</tt> package which would overwrite
+           those already present in <tt>foo</tt>.  This is so that
+           you can install an older version of a package without
+           problems.
          </p>
 
          <p>
-           This usage of <tt>Replaces</tt> only takes effect when
-           both packages are at least partially on the system at
-           once, so that it can only happen if they do not conflict
-           or if the conflict has been overridden.</p>
+           For this usage of <tt>Replaces</tt>, virtual packages (see
+           <ref id="virtual">) are not considered when looking at a
+           <tt>Replaces</tt> field - the packages declared as being
+           replaced must be mentioned by their real names.
+         </p>
+
+         <p>
+           Furthermore, this usage of <tt>Replaces</tt> only takes
+           effect when both packages are at least partially on the
+           system at once, so that it can only happen if they do not
+           conflict or if the conflict has been overridden.
+         </p>
+
        </sect1>
 
        <sect1><heading>Replacing whole packages, forcing their
-           removal
-         </heading>
+           removal</heading>
 
          <p>
            Secondly, <tt>Replaces</tt> allows the packaging system to
            resolve which package should be removed when there is a
            conflict - see <ref id="conflicts">.  This usage only
            takes effect when the two packages <em>do</em> conflict,
-           so that the two effects do not interfere with each other.
+           so that the two usages of this field do not interfere with
+           each other.
          </p>
+
+         <p>
+           In this situation, the package declared as being replaced
+           can be a virtual package, so for example, all mail
+           transport agents (MTAs) would have the following fields in
+           their control files:
+           <example>
+Provides: mail-transport-agent
+Conflicts: mail-transport-agent
+Replaces: mail-transport-agent
+           </example>
+           ensuring that only one MTA can be installed at any one
+           time.
        </sect1>
       </sect>
 
 
         <p>
           A source package may declare a dependency or a conflict on a
-          binary package.  This is done with the control file fields
-          <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
-          <tt>Build-Conflicts</tt>, and
-          <tt>Build-Conflicts-Indep</tt>.  Their semantics are that
-          the dependencies and conflicts they define must be satisfied
-          (as defined earlier for binary packages), when one of the
-          targets in <tt>debian/rules</tt> that the particular field
-          applies to is invoked.
+          binary package, indicating which packages are required to be
+          present on the system in order to build the binary packages
+          from the source package.  This is done with the control file
+          fields <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
+          <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>.
+          The dependencies and conflicts they define must be satisfied
+          (as defined earlier for binary packages) in order to invoke
+          the targets in <tt>debian/rules</tt>, as follows:
 
          <taglist>
            <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
            <item>
              <p>
                 The <tt>Build-Depends</tt> and
-               <tt>Build-Conflicts</tt> fields apply to the targets
+               <tt>Build-Conflicts</tt> fields must be satisfied when
+               any of the following targets is invoked:
                <tt>build</tt>, <tt>binary</tt>, <tt>binary-arch</tt>
                and <tt>binary-indep</tt>.
              </p>
            <item>
              <p>
                 The <tt>Build-Depends-Indep</tt> and
-               <tt>Build-Conflicts-Indep</tt> fields apply to the
-               targets <tt>binary</tt> and <tt>binary-indep</tt>.
+               <tt>Build-Conflicts-Indep</tt> fields must be
+               satisfied when any of the following targets is
+               invoked: <tt>binary</tt> and <tt>binary-indep</tt>.
              </p>
            </item>
          </taglist>
       </heading>
 
       <p>
-       <prgn>dpkg</prgn> can do a certain amount of automatic
-       handling of package configuration files.
-      </p>
-
-      <p>
-       Whether this mechanism is appropriate depends on a number of
-       factors, but basically there are two approaches to any
-       particular configuration file.
-      </p>
-
-      <p>
-       The easy method is to ship a best-effort configuration in the
-       package, and use <prgn>dpkg</prgn>'s conffile mechanism to
-       handle updates.  If the user is unlikely to want to edit the
-       file, but you need them to be able to without losing their
-       changes, and a new package with a changed version of the file
-       is only released infrequently, this is a good approach.
-      </p>
-
-      <p>
-       The hard method is to build the configuration file from
-       scratch in the <prgn>postinst</prgn> script, and to take the
-       responsibility for fixing any mistakes made in earlier
-       versions of the package automatically.  This will be
-       appropriate if the file is likely to need to be different on
-       each system.
+       This chapter has been superseded by <ref id="config files">.
       </p>
 
 
-    <chapt id="sharedlibs"><heading>Shared libraries
-      </heading>
+    <chapt id="sharedlibs"><heading>Shared libraries</heading>
 
       <p>
        Packages containing shared libraries must be constructed with
        a little care to make sure that the shared library is always
        available.  This is especially important for packages whose
-       shared libraries are vitally important, such as the libc.
+       shared libraries are vitally important, such as the C library
+       (currently <tt>libc6</tt>).
       </p>
 
       <p>
-       Firstly, your package should install the shared libraries
-       under their normal names.  For example, the
-       <prgn>libgdbm1</prgn> package should install
-       <tt>libgdbm.so.1.7.3</tt> as
+       Firstly, the package should install the shared libraries under
+       their normal names.  For example, the <tt>libgdbmg1</tt>
+       package should install <tt>libgdbm.so.1.7.3</tt> as
        <tt>/usr/lib/libgdbm.so.1.7.3</tt>.  The files should not be
-       renamed or re-linked by any prerm or postrm scripts;
-       <prgn>dpkg</prgn> will take care of renaming things safely
-       without affecting running programs, and attempts to interfere
-       with this are likely to lead to problems.
+       renamed or re-linked by any <prgn>prerm</prgn> or
+       <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
+       of renaming things safely without affecting running programs,
+       and attempts to interfere with this are likely to lead to
+       problems.
       </p>
 
       <p>
-       Secondly, your package should include the symlink that
+       Secondly, the package should include the symbolic link that
        <prgn>ldconfig</prgn> would create for the shared libraries.
-       For example, the <prgn>libgdbm1</prgn> package should include
-       a symlink from <tt>/usr/lib/libgdbm.so.1</tt> to
-       <tt>libgdbm.so.1.7.3</tt>.  This is needed so that
-       <prgn>ld.so</prgn> can find the library in between the time
-       <prgn>dpkg</prgn> installs it and <prgn>ldconfig</prgn> is run
-       in the <prgn>postinst</prgn> script.  Furthermore, older
-       versions of the package management system required the library
-       must be placed before the symlink pointing to it in the
-       <tt>.deb</tt> file.  This is so that by the time
-       <prgn>dpkg</prgn> comes to install the symlink (overwriting
-       the previous symlink pointing at an older version of the
-       library) the new shared library is already in place.
-       Unfortunately, this was not not always possible, since it
-       highly depends on the behavior of the file system. Some
-       file systems (such as reiserfs) will reorder the files so it
-       doesn't matter in what order you create them. Starting with
-       release <tt>1.7.0</tt> <prgn>dpkg</prgn> will reorder the
-       files itself when building a package.
+       For example, the <prgn>libgdbmg1</prgn> package should include
+       a symbolic link from <tt>/usr/lib/libgdbm.so.1</tt> to
+       <tt>libgdbm.so.1.7.3</tt>.  This is needed so that the dynamic
+       linker (for example <prgn>ld.so</prgn> or
+       <prgn>ld-linux.so.*</prgn>) can find the library between the
+       time that <prgn>dpkg</prgn> installs it and the time that
+       <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
+       script.
+       <footnote>
+         <p>
+           The package management system requires the library to be
+           placed before the symbolic link pointing to it in the
+           <tt>.deb</tt> file.  This is so that when
+           <prgn>dpkg</prgn> comes to install the symlink
+           (overwriting the previous symlink pointing at an older
+           version of the library), the new shared library is already
+           in place.  In the past, this was achieved by creating the
+           library in the temporary packaging directory before
+           creating the symlink.  Unfortunately, this was not always
+           effective, since the building of the tar file in the
+           <tt>.deb</tt> depended on the behavior of the underlying
+           file system.  Some file systems (such as reiserfs) reorder
+           the files so that the order of creation is forgotten.
+           Starting with release <tt>1.7.0</tt>, <prgn>dpkg</prgn>
+           will reorder the files itself as necessary when building a
+           package.  Thus it is no longer important to concern
+           oneself with the order of file creation.
+         </p>
+       </footnote>
       </p>
 
       <p>
-       Thirdly, the development package should contain a symlink for
-       the shared library without a version number.  For example, the
-       <tt>libgdbm1-dev</tt> package should include a symlink from
-       <tt>/usr/lib/libgdm.so</tt> to <tt>libgdm.so.1.7.3</tt>.  This
-       symlink is needed by <prgn>ld</prgn> when compiling packages
-       as it will only look for <tt>libgdm.so</tt> and
-       <tt>libgdm.a</tt> when compiling dynamically or statically,
-       respectively.
+       Thirdly, the associated development package should contain a
+       symlink for the shared library without a version number.  For
+       example, the <tt>libgdbmg1-dev</tt> package should include a
+       symlink from <tt>/usr/lib/libgdbm.so</tt> to
+       <tt>libgdbm.so.1.7.3</tt>.  This symlink is needed by the
+       linker (<prgn>ld</prgn>) when compiling packages, as it will
+       only look for <tt>libgdbm.so</tt> when compiling dynamically.
+      </p>
+
+      <p>
+       Any package installing shared libraries in one of the default
+       library directories of the dynamic linker (which are currently
+       <tt>/usr/lib</tt> and <tt>/lib</tt>) or a directory that is
+       listed in <tt>/etc/ld.so.conf</tt>
+       <footnote>
+         <p>
+           These are currently
+           <list>
+             <item><p>/usr/X11R6/lib/Xaw3d</p></item>
+             <item><p>/usr/local/lib</p></item>
+             <item><p>/usr/lib/libc5-compat</p></item>
+             <item><p>/lib/libc5-compat</p></item>
+             <item><p>/usr/X11R6/lib</p></item>
+           </list>
+         </p>
+       </footnote>
+       must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
+       script if and only if the first argument is <tt>configure</tt>
+       and should call it in the <prgn>postrm</prgn> script if the
+       first argument is <tt>remove</tt>.
       </p>
 
       <p>
-       Any package installing shared libraries in a directory that's listed
-       in <tt>/etc/ld.so.conf</tt> or in one of the default library
-       directories of <prgn>ld.so</prgn> (currently, these are <tt>/usr/lib</tt>
-       and <tt>/lib</tt>) must call <prgn>ldconfig</prgn> in its <prgn>postinst</prgn>
-       script if and only if the first argument is `configure'. However, it
-       is important not to call <prgn>ldconfig</prgn> in the postrm or preinst
-       scripts in the case where the package is being upgraded (see <ref
-                                                                         id="unpackphase">), as <prgn>ldconfig</prgn> will see the temporary names
-       that <prgn>dpkg</prgn> uses for the files while it is
+       However, <prgn>postrm</prgn> and <prgn>preinst</prgn> scripts
+       <em>must not</em> call <prgn>ldconfig</prgn> in the case where
+       the package is being upgraded (see <ref id="unpackphase"> for
+       details), as <prgn>ldconfig</prgn> will see the temporary
+       names that <prgn>dpkg</prgn> uses for the files while it is
        installing them and will make the shared library links point
        to them, just before <prgn>dpkg</prgn> continues the
-       installation and removes the links!
+       installation and renames the temporary files!
       </p>
 
-      <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
-       </heading>
+      <sect>
+       <heading>Handling shared library dependencies - the
+         <tt>shlibs</tt> system</heading>
+
+       <p>
+         If a package contains a binary or library which links to a
+         shared library, we must ensure that when the package is
+         installed on the system, all of the libraries needed are
+         also installed.  This requirement led to the creation of the
+         <tt>shlibs</tt> system, which is very simple in its design:
+         any package which <em>provides</em> a shared library also
+         provides information on the package dependencies required to
+         ensure the presence of this library, and any package which
+         <em>uses</em> a shared library uses this information to
+         determine the dependencies it requires.  The files which
+         contain the mapping from shared libraries to the necessary
+         dependency information are called <tt>shlibs</tt> files.
+       </p>
+
+       <p>
+         Thus, when a package is built which contains any shared
+         libraries, it must provide a <tt>shlibs</tt> file for other
+         packages to use, and when a package is built which contains
+         any shared libraries or compiled binaries, it must run
+         <prgn>dpkg-shlibdeps</prgn> on these to determine the
+         libraries used and hence the dependencies needed by this
+         package.
+         <footnote>
+           <p>
+             In the past, the shared libraries linked to were
+             determined by calling <prgn>ldd</prgn>, but now
+             <prgn>objdump</prgn> to do this.  The only change this
+             makes to package building is that
+             <prgn>dpkg-shlibdeps</prgn> must also be run on shared
+             libraries, whereas in the past this was unnecessary.
+             The rest of this footnote explains the advantage that
+             this method gives.
+           </p>
 
-       <p>
-         This file is for use by <prgn>dpkg-shlibdeps</prgn> and is
-         required when your package provides shared libraries.
-       </p>
+           <p>
+             We say that a binary <tt>foo</tt> <em>directly</em> uses
+             a library <tt>libbar</tt> if it is explicitly linked
+             with that library (that is, it uses the flag
+             <tt>-lbar</tt> during the linking stage).  Other
+             libraries that are needed by <tt>libbar</tt> are linked
+             <em>indirectly</em> to <tt>foo</tt>, and the dynamic
+             linker will load them automatically when it loads
+             <tt>libbar</tt>.  A package should needs to depend on
+             the libraries it directly uses, and the dependencies for
+             those libraries should automatically pull in the other
+             libraries.
+           </p>
 
-       <p>
-         Each line is of the form:
-         <example>
-           <var>library-name</var> <var>version-or-soname</var> <var>dependencies ...</var>
-         </example>
-       </p>
+           <p>
+             Unfortunately, the <prgn>ldd</prgn> program shows both
+             the directly and indirectly used libraries, meaning that
+             the dependencies determined included both direct and
+             indirect dependencies.  The use of <prgn>objdump</prgn>
+             avoids this problem by determining only the directly
+             used libraries.
+           </p>
 
-       <p>
-         <var>library-name</var> is the name of the shared library,
-         for example <tt>libc5</tt>.
+           <p>
+             A good example of where this helps is the following.  We
+             could update <tt>libimlib</tt> with a new version that
+             supports a new graphics format called dgf (but retaining
+             the same major version number).  If we used the old
+             <prgn>ldd</prgn> method, every package that uses
+             <tt>libimlib</tt> would need to be recompiled so it
+             would also depend on <tt>libdgf</tt> or it wouldn't run
+             due to missing symbols.  However with the new system,
+             packages using <tt>libimlib</tt> can rely on
+             <tt>libimlib</tt> itself having the dependency on
+             <tt>libdgf</tt> and so they would not need rebuilding.
+           </p>
+         </footnote>
        </p>
 
        <p>
-         <var>version-or-soname</var> is the soname of the library -
-         i.e., the thing that must exactly match for the library to be
-         recognized by <prgn>ld.so</prgn>.  Usually this is the major
-         version number of the library.
+         In the following sections, we will first describe where the
+         various <tt>shlibs</tt> files are to be found, then how to
+         use <prgn>dpkg-shlibdeps</prgn>, and finally the
+         <tt>shlibs</tt> file format and how to create them if your
+         package contains a shared library.
        </p>
+      </sect>
 
-       <p>
-         <var>dependencies</var> has the same syntax as a dependency
-         field in a binary package control file.  It should give
-         details of which package(s) are required to satisfy a binary
-         built against the version of the library contained in the
-         package.  See <ref id="depsyntax">.
-       </p>
+      <sect><heading>The <tt>shlibs</tt> files present on the system
+       </heading>
 
        <p>
-         For example, if the package <tt>foo</tt> contains
-         <tt>libfoo.so.1.2.3</tt>, where the soname of the library is
-         <tt>libfoo.so.1</tt>, and the first version of the package
-         which contained a minor number of at least <tt>2.3</tt> was
-         <var>1.2.3-1</var>, then the package's <var>shlibs</var>
-         could say:
-         <example>
-           libfoo 1    foo (>= 1.2.3-1)
-         </example>
+         There are several places where <tt>shlibs</tt> files are
+         found.  The following list gives them in the order in which
+         they are read by <prgn>dpkg-shlibdeps</prgn>.  (The first
+         one which gives the required information is used.)
        </p>
 
        <p>
-         The version-specific dependency is to avoid warnings from
-         <prgn>ld.so</prgn> about using older shared libraries with
-         newer binaries.</p>
-      </sect>
-
-      <sect><heading>Further Technical information on
-         <tt>shlibs</tt></heading>
-
-       <sect1><heading><em>What</em> are the <tt>shlibs</tt> files?
-         </heading>
-
-         <p>
-           The <tt>debian/shlibs</tt> file provides a way of checking
-           for shared library dependencies on packaged binaries.
-           They are intended to be used by package maintainers to
-           make their lives easier.
-         </p>
-
-         <p>
-           Other <tt>shlibs</tt> files that exist on a Debian system are
-           <list>
-             <item> <p><tt>/etc/dpkg/shlibs.default</tt></p></item>
-             <item> <p><tt>/etc/dpkg/shlibs.override</tt></p></item>
-             <item> <p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
-             <item> <p><tt>debian/shlibs.local</tt></p></item>
-           </list>
-           These files are used by <prgn>dpkg-shlibdeps</prgn> when
-           creating a binary package.</p>
-       </sect1>
-
-       <sect1><heading><em>How</em> does <prgn>dpkg-shlibdeps</prgn>
-           work?
-         </heading>
-         <p>
-           <prgn>dpkg-shlibdeps</prgn>
-           determines the shared libraries directly
-           <footnote>
+         <taglist>
+           <tag><tt>debian/shlibs.local</tt></tag>
+           <item>
              <p>
-               It used to do this by calling <prgn>ldd</prgn>, but it
-               now calls <prgn>objdump</prgn> to do this. This
-               requires a couple of changes in the way that packages
-               are built.
+               This lists overrides for this package.  Its use is
+               described below (see <ref id="shlibslocal">).
              </p>
+           </item>
+
+           <tag><tt>/etc/dpkg/shlibs.override</tt></tag>
+           <item>
              <p>
-               A binary <tt>foo</tt> directly uses a library
-               <tt>libbar</tt> if it is linked with that
-               library. Other libraries that are needed by
-               <tt>libbar</tt> are linked indirectly to <tt>foo</tt>,
-               and the dynamic linker will load them automatically
-               when it loads <tt>libbar</tt>. Running<prgn>ldd</prgn>
-               lists all of the libraries used, both directly and
-               indirectly; but <prgn>objdump</prgn> only lists the
-               directly linked libraries. A package only needs to
-               depend on the libraries it is directly linked to,
-               since the dependencies for those libraries should
-               automatically pull in the other libraries.
+               This lists global overrides.  This list is normally
+               empty.  It is maintained by the local system
+               administrator.
              </p>
+           </item>
+
+           <tag><tt>DEBIAN/shlibs</tt> files in the `build directory'</tag>
+           <item>
              <p>
-               This change does mean a change in the way packages are
-               build though: currently <prgn>dpkg-shlibdeps</prgn> is
-               only run on binaries. But since we will now rely on the
-               libraries depending on the libraries they themselves
-               need, the packages containing those libraries will
-               need to run <prgn>dpkg-shlibdeps</prgn> on the
-               libraries.
+               When packages are being built, any
+               <tt>debian/shlibs</tt> files are copied into the
+               control file area of the temporary build directory and
+               given the name <tt>shlibs</tt>.  These files give
+               details of any shared libraries included in the
+               package.
+               <footnote>
+                 <p>
+                   An example may help here.  Let us say that the
+                   source package <tt>foo</tt> generates two binary
+                   packages, <tt>libfoo2</tt> and
+                   <tt>foo-runtime</tt>.  When building the binary
+                   packages, the two packages are created in the
+                   directories <tt>debian/libfoo2</tt> and
+                   <tt>debian/foo-runtime</tt> respectively.
+                   (<tt>debian/tmp</tt> could be used instead of one
+                   of these.)  Since <tt>libfoo2</tt> provides the
+                   <tt>libfoo</tt> shared library, it will require a
+                   <tt>shlibs</tt> file, which will be installed in
+                   <tt>debian/libfoo2/DEBIAN/shlibs</tt>, eventually
+                   to become
+                   <tt>/var/lib/dpkg/info/libfoo2.shlibs</tt>.  Then
+                   when <prgn>dpkg-shlibdeps</prgn> is run on the
+                   executable
+                   <tt>debian/foo-runtime/usr/bin/foo-prog</tt>, it
+                   will examine the
+                   <tt>debian/libfoo2/DEBIAN/shlibs</tt> file to
+                   determine whether <tt>foo-prog</tt>'s library
+                   dependencies are satisfied by any of the libraries
+                   provided by <tt>libfoo2</tt>.  For this reason,
+                   <prgn>dpkg-shlibdeps</prgn> must only be run once
+                   all of the individual binary packages'
+                   <tt>shlibs</tt> files have been installed into the
+                   build directory.
+                 </p>
+               </footnote>
              </p>
+           </item>
+
+           <tag><tt>/var/lib/dpkg/info/*.shlibs</tt></tag>
+           <item>
              <p>
-               A good example where this would help us is the current
-               mess with multiple version of the <tt>mesa</tt>
-               library. With the <prgn>ldd</prgn>-based system, every
-               package that uses <tt>mesa</tt> needs to add a
-               dependency on <tt>svgalib|svgalib-dummy</tt> in order
-               to handle the glide <tt>mesa</tt> variant.  With an
-               <prgn>objdump</prgn>-based system this isn't necessary
-               anymore and would have saved everyone a lot of work.
+               These are the <tt>shlibs</tt> files corresponding to
+               all of the packages installed on the system, and are
+               maintained by the relevant package maintainers.
              </p>
+           </item>
+
+           <tag><tt>/etc/dpkg/shlibs.default</tt></tag>
+           <item>
              <p>
-               Another example: we could update <tt>libimlib</tt>
-               with a new version that supports a new graphics format
-               called dgf. If we use the old <prgn>ldd</prgn> method,
-               every package that uses <tt>libimlib</tt> would need
-               to be recompiled so it would also depend on
-               <tt>libdgf</tt> or it wouldn't run due to missing
-               symbols. However with the new system, packages using
-               <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
-               having the dependency on <tt>libdgf</tt> and wouldn't
-               need to be updated.
+               This file lists any shared libraries whose packages
+               have failed to provide correct <tt>shlibs</tt> files.
+               It was used when the <tt>shlibs</tt> setup was first
+               introduced, but it is now normally empty.  It is
+               maintained by the <tt>dpkg</tt> maintainer.
              </p>
-           </footnote>
-           used by the compiled binaries and libraries passed through
-           on its command line.
-         </p>
+           </item>
+         </taglist>
+       </p>
+      </sect>
 
-         <p>
-           For each shared library linked to,
-           <prgn>dpkg-shlibdeps</prgn> needs to know
-           <list compact="compact">
-             <item><p>the package containing the library, and</p></item>
-             <item><p>the library version number,</p></item>
-           </list>
-           and it scans the following files in this order:
-           <enumlist compact="compact">
-             <item><p><tt>debian/shlibs.local</tt></p></item>
-             <item><p><tt>/etc/dpkg/shlibs.override</tt></p></item>
-             <item><p><tt>/var/lib/dpkg/info/*.shlibs</tt></p></item>
-             <item><p><tt>/etc/dpkg/shlibs.default</tt></p></item>
-           </enumlist>
-         </p>
-       </sect1>
+      <sect>
+       <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
+           <tt>shlibs</tt> files</heading>
 
-       <sect1><heading><em>Who</em> maintains the various
-           <tt>shlibs</tt> files?
-         </heading>
+       <p>
+         Put a call to <prgn>dpkg-shlibdeps</prgn> into your
+         <tt>debian/rules</tt> file.  If your package contains only
+         compiled binaries and libraries (but no scripts), you can
+         use a command such as:
+         <example>
+dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
+  debian/tmp/usr/lib/*
+         </example>
+         Otherwise, you will need to explicitly list the compiled
+         binaries and libraries.
+         <footnote>
+           <p>
+             If you are using <tt>debhelper</tt>, the
+             <prgn>dh_shlibdeps</prgn> program will do this work for
+             you.  It will also correctly handle multi-binary
+             packages.
+           </p>
+         </footnote>
+       </p>
 
-         <p>
-           <list compact="compact">
-             <item>
-               <p><tt>/etc/dpkg/shlibs.default</tt> - the maintainer
-                 of dpkg</p>
-             </item>
-             <item>
-               <p>
-                 <tt>/var/lib/dpkg/info/<var>package</var>.shlibs</tt>
-                 - the maintainer of each package</p>
-             </item>
-             <item>
-               <p>
-                 <tt>/etc/dpkg/shlibs.override</tt> - the local
-                 system administrator</p>
-             </item>
-             <item>
-               <p><tt>debian/shlibs.local</tt> - the maintainer of
-                 the package
-               </p>
-             </item>
-           </list>
-           The <tt>shlibs.default</tt> file is managed by
-           <prgn>dpkg</prgn>. The entries in <tt>shlibs.default</tt>
-           that are provided by <prgn>dpkg</prgn> are just there to
-           fix things until the shared library packages all have
-           <tt>shlibs</tt> files.
-         </p>
-       </sect1>
+       <p>
+         This command puts the dependency information into the
+         <tt>debian/substvars</tt> file, which is then used by
+         <prgn>dpkg-gencontrol</prgn>.  You will need to place a
+         <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
+         field in the control file for this to work.
+       </p>
 
-       <sect1><heading><em>How</em> to use <prgn>dpkg-shlibdeps</prgn> and
-           the <tt>shlibs</tt> files
-         </heading>
+       <p>
+         If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
+         done.  If it does complain you might need to create your own
+         <tt>debian/shlibs.local</tt> file, as explained below (see
+         <ref id="shlibslocal">).
+       </p>
+
+       <p>
+         If you have multiple binary packages, you will need to call
+         <prgn>dpkg-shlibdeps</prgn> on each one which contains
+         compiled libraries or binaries.  In such a case, you will
+         need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
+         utilities to specify a different <tt>substvars</tt> file.
+         For more details on this and other options, see <manref
+         name="dpkg-shlibdeps" section="1">.
+       </p>
+      </sect>
+
+      <sect id="shlibs"><heading>The <tt>shlibs</tt> File Format
+       </heading>
+
+       <p>
+         Each <tt>shlibs</tt> file has the same format.  Lines
+         beginning with <tt>#</tt> are considered to be commments and
+         are ignored.  Each line is of the form:
+         <example>
+<var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
+         </example>
+       </p>
 
-         <sect2><heading>If your package doesn't provide a shared
-             library
-           </heading>
+       <p>
+         We will explain this by reference to the example of the
+         <tt>zlib1g</tt> package, which (at the time of writing)
+         installs the shared library <tt>/usr/lib/libz.so.1.1.3</tt>.
+       </p>
 
+       <p>
+         <var>library-name</var> is the name of the shared library,
+         in this case <tt>libz</tt>.  (This must match the name part
+         of the soname, see below.)
+       </p>
+
+       <p>
+         <var>soname-version-number</var> is the version part of the
+         soname of the library.  The soname is the thing that must
+         exactly match for the library to be recognized by the
+         dynamic linker, and is usually of the form
+         <tt><var>name</var>.so.<var>major-version</var></tt>, in our
+         example, <tt>libz.so.1</tt>.
+         <footnote>
            <p>
-             Put a call to <prgn>dpkg-shlibdeps</prgn> into your
-             <tt>debian/rules</tt> file.  If your package contains
-             only binaries (e.g. no scripts) use:
+             This can be determined using the command
              <example>
-               dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/*
+objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
              </example>
-             If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
-             done. If it does complain you might need to create your
-             own <tt>debian/shlibs.local</tt> file.</p>
-         </sect2>
+           </p>
+         </footnote>
+         The version part is the part which comes after
+         <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
+       </p>
 
-         <sect2><heading>If your package provides a shared library
-           </heading>
+       <p>
+         <var>dependencies</var> has the same syntax as a dependency
+         field in a binary package control file.  It should give
+         details of which packages are required to satisfy a binary
+         built against the version of the library contained in the
+         package.  See <ref id="depsyntax"> for details.
+       </p>
 
+       <p>
+         In our example, if the first version of the <tt>zlib1g</tt>
+         package which contained a minor number of at least
+         <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
+         <tt>shlibs</tt> entry for this library could say:
+         <example>
+libz 1 zlib1g (>= 1:1.1.3)
+         </example>
+         The version-specific dependency is to avoid warnings from
+         the dynamic linker about using older shared libraries with
+         newer binaries.
+       </p>
+      </sect>
+
+      <sect>
+       <heading>Providing a <tt>shlibs</tt> file</heading>
+
+       <p>
+         If your package provides a shared library, you should create
+         a <tt>shlibs</tt> file following the format described above.
+         It is usual to call this file <tt>debian/shlibs</tt> (but if
+         you have multiple binary packages, you might want to call it
+         <tt>debian/shlibs.<var>package</var></tt> instead).  Then
+         let <tt>debian/rules</tt> install it in the control area:
+         <example>
+install -m644 debian/shlibs debian/tmp/DEBIAN
+         </example>
+         or, in the case of a multi-binary package:
+         <example>
+install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
+         </example>
+         An alternative way of doing this is to create the
+         <tt>shlibs</tt> file in the control area directly from
+         <tt>debian/rules</tt> without using a <tt>debian/shlibs</tt>
+         file at all,
+         <footnote>
            <p>
-             Create a <tt>debian/shlibs</tt> file and let
-             <tt>debian/rules</tt> install it in the control area:
-             <example>
-               install -m644 debian/shlibs debian/tmp/DEBIAN
-             </example>
-             If your package contains additional binaries see above.
+             This is what <prgn>dh_makeshlibs</prgn> in the
+             <tt>debhelper</tt> suite does.
            </p>
-         </sect2>
-       </sect1>
+         </footnote>
+         since the <tt>debian/shlibs</tt> file itself is ignored by
+         <prgn>dpkg-shlibdeps</prgn>.
+       </p>
 
-       <sect1><heading><em>How</em> to write
-           <tt>debian/shlibs.local</tt>
-         </heading>
+       <p>
+         As <prgn>dpkg-shlibdeps</prgn> reads the
+         <tt>DEBIAN/shlibs</tt> files in all of the binary packages
+         being built from this source package, all of the
+         <tt>DEBIAN/shlibs</tt> files should be installed before
+         <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
+         packages.
+       </p>
+      </sect>
 
-         <p>
-           This file is intended only as a <em>temporary</em> fix if
-           your binaries depend on a library which doesn't provide
-           its own <tt>/var/lib/dpkg/info/*.shlibs</tt> file yet.
-         </p>
+      <sect id="shlibslocal">
+       <heading>Writing the <tt>debian/shlibs.local</tt> file</heading>
 
-         <p>
-           Let's assume you are packaging a binary <tt>foo</tt>. Your
-           output in building the package might look like this.
-           <example>
-             $ ldd foo
-             libbar.so.1 => /usr/X11R6/lib/libbar.so.1.0 (0x4001e000)
-             libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4002c000)
-             libc.so.6 => /lib/libc.so.6 (0x40114000)
-             /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
-           </example>
-           And when you ran <prgn>dpkg-shlibdeps</prgn>
-           <example>
-             $ dpkg-shlibdeps -O foo
-             dpkg-shlibdeps: warning: unable to find dependency information for shared library libbar
-             (soname 1, path /usr/X11R6/lib/libbar.so.1.0, dependency field Depends)
-             shlibs:Depends=libc6 (>= 2.2.1), xlibs (>= 4.0.1-11)
-           </example>
-           The <prgn>foo</prgn> binary depends on the
-           <prgn>libbar</prgn> shared library, but no package seems
-           to provide a <tt>*.shlibs</tt> file in
-           <tt>/var/lib/dpkg/info/</tt>.  Let's determine the package
-           responsible:
-         </p>
+       <p>
+         This file is intended only as a <em>temporary</em> fix if
+         your binaries or libraries depend on a library whose package
+         does not yet provide a correct <tt>shlibs</tt> file.
+       </p>
 
-         <p>
-           <example>
-             $ dpkg -S /usr/X11R6/lib/libbar.so.1.0
-             bar1: /usr/X11R6/lib/libbar.so.1.0
-             $ dpkg -s bar1 | grep Version
-             Version: 1.0-1
-           </example>
-           This tells us that the <prgn>bar1</prgn> package, version
-           1.0-1 is the one we are using. Now we can create our own
-           <tt>debian/shlibs.local</tt> to temporarily fix the above
-           problem. Include the following line into your
-           <tt>debian/shlibs.local</tt> file.
-           <example>
-             libbar 1 bar1 (>= 1.0-1)
-           </example>
-           Now your package build should work. As soon as the
-           maintainer of <prgn>libbar1</prgn> provides a
-           <tt>shlibs</tt> file, you can remove your
-           <tt>debian/shlibs.local</tt> file.
-         </p>
-       </sect1>
+       <p>
+         We will assume that you are trying to package a binary
+         <tt>foo</tt>.  When you try running
+         <prgn>dpkg-shlibdeps</prgn> you get the following error
+         message (<tt>-O</tt> displays the dependency information on
+         <tt>stdout</tt> instead of writing it to
+         <tt>debian/substvars</tt>, and the lines have been wrapped
+         for ease of reading):
+         <example>
+$ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
+dpkg-shlibdeps: warning: unable to find dependency
+  information for shared library libbar (soname 1,
+  path /usr/lib/libbar.so.1, dependency field Depends)
+shlibs:Depends=libc6 (>= 2.2.2-2)
+         </example>
+         You can then run <prgn>ldd</prgn> on the binary to find the
+         full location of the library concerned:
+         <example>
+$ ldd foo
+libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
+libc.so.6 => /lib/libc.so.6 (0x40032000)
+/lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
+         </example>
+         So the <prgn>foo</prgn> binary depends on the
+         <prgn>libbar</prgn> shared library, but no package seems to
+         provide a <tt>*.shlibs</tt> file handling
+         <tt>libbar.so.1</tt> in <tt>/var/lib/dpkg/info/</tt>.  Let's
+         determine the package responsible:
+         <example>
+$ dpkg -S /usr/lib/libbar.so.1
+bar1: /usr/lib/libbar.so.1
+$ dpkg -s bar1 | grep Version
+Version: 1.0-1
+         </example>
+         This tells us that the <tt>bar1</tt> package, version 1.0-1,
+         is the one we are using.  Now we can file a bug against the
+         <tt>bar1</tt> package and create our own
+         <tt>debian/shlibs.local</tt> to locally fix the problem.
+         Including the following line into your
+         <tt>debian/shlibs.local</tt> file:
+         <example>
+libbar 1 bar1 (>= 1.0-1)
+         </example>
+         should allow the package build to work.
+       </p>
+
+       <p>
+         As soon as the maintainer of <tt>bar1</tt> provides a
+         correct <tt>shlibs</tt> file, you should remove this line
+         from your <tt>debian/shlibs.local</tt> file.  (You should
+         probably also then have a versioned <tt>Build-Depends</tt>
+         on <tt>bar1</tt> to help ensure that others do not have the
+         same problem building your package.)
+       </p>
       </sect>
     </chapt>
 
     <chapt><heading>The Operating System</heading>
 
-
       <sect>
        <heading>File system hierarchy</heading>
 
          <p>
            For example, the <prgn>emacs</prgn> package will contain
            <example>
-             mkdir -p /usr/local/lib/emacs/site-lisp || true
+mkdir -p /usr/local/lib/emacs/site-lisp || true
            </example>
            in the <tt>postinst</tt> script, and
            <example>
-             rmdir /usr/local/lib/emacs/site-lisp || true
-             rmdir /usr/local/lib/emacs || true
+rmdir /usr/local/lib/emacs/site-lisp || true
+rmdir /usr/local/lib/emacs || true
            </example>
            in the <tt>prerm</tt> script.</p>
 
            permissions 2775 (group-writable and set-group-id) and be
            owned by <tt>root.staff</tt>.</p>
        </sect1>
+       <sect1>
+         <heading>The system-wide mail directory</heading>
+         <p>
+           The system-wide mail directory is <tt>/var/mail</tt>. This
+           directory is part of the base system and should not owned
+           by any particular mail agents.  The use of the old
+           location <tt>/var/spool/mail</tt> is deprecated, even
+           though the spool may still be physically located there.
+           To maintain partial upgrade compatibility for systems
+           which have <tt>/var/spool/mail</tt> as their physical mail
+           spool, packages using <tt>/var/mail</tt> must depend on
+           either <package>libc6</package> (&gt;= 2.1.3-13), or on
+           <package>base-files</package> (&gt;= 2.2.0), or on later
+           versions of either one of these packages.
+         </p>
+       </sect1>
+
       </sect>
 
+
+
       <sect>
        <heading>Users and groups</heading>
 
            <prgn>bind</prgn> would have a lower number than the
            script that starts <prgn>inn</prgn> so that it runs first:
            <example>
-             /etc/rc2.d/S17bind
-             /etc/rc2.d/S70inn
+/etc/rc2.d/S17bind
+/etc/rc2.d/S70inn
            </example>
          </p>
        </sect1>
            should include a <tt>test</tt> statement at the top of the
            script, like this:
            <example>
-             test -f <var>program-executed-later-in-script</var> || exit 0
+test -f <var>program-executed-later-in-script</var> || exit 0
            </example></p>
 
          <p>
            To get the default behavior for your package, put in your
            <tt>postinst</tt> script
            <example>
-             update-rc.d <var>package</var> defaults &gt;/dev/null
+update-rc.d <var>package</var> defaults &gt;/dev/null
            </example>
            and in your <tt>postrm</tt>
            <example>
-             if [ purge = "$1" ]; then
-             update-rc.d <var>package</var> remove &gt;/dev/null
-             fi
+if [ purge = "$1" ]; then
+  update-rc.d <var>package</var> remove &gt;/dev/null
+fi
            </example></p>
 
          <p>
 
          <p>
            <example>
-             #!/bin/sh
-             #
-             # Original version by Robert Leslie
-             # &lt;rob@mars.org&gt;, edited by iwj and cs
-
-             test -x /usr/sbin/named || exit 0
-
-              # Source defaults file.
-              PARAMS=''
-              if [ -f /etc/default/bind ]; then
-                . /etc/default/bind
-              fi
-
-
-             case "$1" in
-             start)
-             echo -n "Starting domain name service: named"
-             start-stop-daemon --start --quiet --exec /usr/sbin/named \
-                               -- $PARAMS
-             echo "."
-             ;;
-             stop)
-             echo -n "Stopping domain name service: named"
-             start-stop-daemon --stop --quiet  \
-             --pidfile /var/run/named.pid --exec /usr/sbin/named
-             echo "."
-             ;;
-             restart)
-             echo -n "Restarting domain name service: named"
-             start-stop-daemon --stop --quiet  \
-             --pidfile /var/run/named.pid --exec /usr/sbin/named
-             start-stop-daemon --start --verbose --exec /usr/sbin/named \
-                               -- $PARAMS
-             echo "."
-             ;;
-             force-reload|reload)
-             echo -n "Reloading configuration of domain name service: named"
-             start-stop-daemon --stop --signal 1 --quiet  \
-             --pidfile /var/run/named.pid --exec /usr/sbin/named
-             echo "."
-             ;;
-             *)
-             echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
-             exit 1
-             ;;
-             esac
-
-             exit 0
+#!/bin/sh
+#
+# Original version by Robert Leslie
+# &lt;rob@mars.org&gt;, edited by iwj and cs
+
+test -x /usr/sbin/named || exit 0
+
+# Source defaults file.
+PARAMS=''
+if [ -f /etc/default/bind ]; then
+  . /etc/default/bind
+fi
+
+
+case "$1" in
+start)
+  echo -n "Starting domain name service: named"
+  start-stop-daemon --start --quiet --exec /usr/sbin/named \
+                    -- $PARAMS
+  echo "."
+  ;;
+stop)
+  echo -n "Stopping domain name service: named"
+  start-stop-daemon --stop --quiet  \
+    --pidfile /var/run/named.pid --exec /usr/sbin/named
+  echo "."
+  ;;
+restart)
+  echo -n "Restarting domain name service: named"
+  start-stop-daemon --stop --quiet  \
+    --pidfile /var/run/named.pid --exec /usr/sbin/named
+  start-stop-daemon --start --verbose --exec /usr/sbin/named \
+                    -- $PARAMS
+  echo "."
+  ;;
+force-reload|reload)
+  echo -n "Reloading configuration of domain name service: named"
+  start-stop-daemon --stop --signal 1 --quiet  \
+    --pidfile /var/run/named.pid --exec /usr/sbin/named
+  echo "."
+  ;;
+*)
+  echo "Usage: /etc/init.d/bind {start|stop|restart|reload|force-reload}" >&2
+  exit 1
+  ;;
+esac
+
+exit 0
            </example>
          </p>
 
          </p>
          <p>
            <example>
-             # Specified parameters to pass to named. See named(8).
-              # You may uncomment the following line, and edit to taste.
-              #PARAMS="-u nobody"
+# Specified parameters to pass to named. See named(8).
+# You may uncomment the following line, and edit to taste.
+#PARAMS="-u nobody"
            </example>
          </p>
 
            and having named running in all runlevels, it can say in
            its <tt>postinst</tt>:
            <example>
-             update-rc.d bind defaults >/dev/null
+update-rc.d bind defaults >/dev/null
            </example>
            And in its <tt>postrm</tt>, to remove the links when the
            package is purged:
            <example>
-             if [ purge = "$1" ]; then
-             update-rc.d bind remove >/dev/null
-             fi
+if [ purge = "$1" ]; then
+  update-rc.d bind remove >/dev/null
+fi
            </example></p>
        </sect1></sect>
 
          via cron, it should place a file with the name of the
          package in one of the following directories:
          <example>
-           /etc/cron.daily
-           /etc/cron.weekly
-           /etc/cron.monthly
+/etc/cron.daily
+/etc/cron.weekly
+/etc/cron.monthly
          </example>
          As these directory names imply, the files within them are
          executed on a daily, weekly, or monthly basis,
        <p>
          If a certain job has to be executed more frequently than
          daily, the package should install a file
-         <tt>/etc/cron.d/<var>package-name</var></tt>. This file uses
+         <tt>/etc/cron.d/<var>package</var></tt>. This file uses
          the same syntax as <tt>/etc/crontab</tt> and is processed by
          <prgn>cron</prgn> automatically. The file must also be
          treated as a configuration file. (Note, that entries in the
                mention ``him'' directly.  For example, if you think
                of saying
                <example>
-                 I'm starting network daemons: nfsd mountd.
+I'm starting network daemons: nfsd mountd.
                </example>
                just say
                <example>
-                 Starting network daemons: nfsd mountd.
-               </example></p></item>
-         </list></p>
+Starting network daemons: nfsd mountd.
+               </example>
+             </p>
+           </item>
+         </list>
+       </p>
 
        <p>
          The following formats should be used</p>
                daemons.  The output should look like this (a single
                line, no leading spaces):
                <example>
-                 Starting &lt;description&gt;: &lt;daemon-1&gt; &lt;daemon-2&gt; &lt;...&gt; &lt;daemon-n&gt;.
+Starting &lt;description&gt;: &lt;daemon-1&gt; &lt;daemon-2&gt; &lt;...&gt; &lt;daemon-n&gt;.
                </example>
                The &lt;description&gt; should describe the subsystem
                the daemon or set of daemons are part of, while
              <p>
                For example, the output of /etc/init.d/lpd would look like:
                <example>
-                 Starting printer spooler: lpd.
+Starting printer spooler: lpd.
                </example></p>
 
              <p>
                This can be achieved by saying
                <example>
-                 echo -n "Starting printer spooler: lpd"
-                 start-stop-daemon --start --quiet lpd
-                 echo "."
+echo -n "Starting printer spooler: lpd"
+start-stop-daemon --start --quiet lpd
+echo "."
                </example>
                in the script. If you have more than one daemon to
                start, you should do the following:
                <example>
-                 echo -n "Starting remote file system services:"
-                 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
-                 echo -n " mountd"; start-stop-daemon --start --quiet mountd
-                 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
-                 echo "."
+echo -n "Starting remote file system services:"
+echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
+echo -n " mountd"; start-stop-daemon --start --quiet mountd
+echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
+echo "."
                </example>
                This makes it possible for the user to see what takes
                so long and when the final daemon has been
                example above the system administrator can easily
                comment out a line if he don't wants to start a
                specific daemon, while the displayed message still
-               looks good.</p></item>
-
+               looks good.
+             </p>
+           </item>
 
            <item>
              <p>when something needs to be configured.</p>
                If you have to set up different parameters of the
                system upon boot up, you should use this format:
                <example>
-                 Setting &lt;parameter&gt; to `&lt;value&gt;'.
-               </example></p>
+Setting &lt;parameter&gt; to `&lt;value&gt;'.
+               </example>
+             </p>
 
              <p>
                You can use the following echo statement to get the quotes right:
                <example>
-                 echo "Setting DNS domainname to \`"value"'."
-               </example></p>
+echo "Setting DNS domainname to \`"value"'."
+               </example>
+             </p>
 
              <p>
                Note that the left quotation mark (`) is different
-               from the right (').</p></item>
+               from the right (').
+             </p>
+           </item>
 
            <item>
              <p>when a daemon is stopped.</p>
              <p>
                So stopping the printer daemon will like like this:
                <example>
-                 Stopping printer spooler: lpd.
+Stopping printer spooler: lpd.
                </example></p></item>
 
            <item>
                via `netdate' or killing all processes when the system
                comes down. Your message should like this:
                <example>
-                 Doing something very useful...done.
+Doing something very useful...done.
                </example>
                You should print the `done.' right after the job has been completed,
                so that the user gets informed why he has to wait. You can get this
                behavior by saying
                <example>
-                 echo -n "Doing something very useful..."
-                 do_something
-                 echo "done."
+echo -n "Doing something very useful..."
+do_something
+echo "done."
                </example>
-               in your script.</p></item>
+               in your script.
+             </p>
+           </item>
 
            <item>
              <p>when the configuration is reloaded.</p>
                When a daemon is forced to reload its configuration
                files you should use the following format:
                <example>
-                 Reloading &lt;daemon's-name&gt; configuration...done.
-               </example></p></item>
+Reloading &lt;daemon's-name&gt; configuration...done.
+               </example>
+             </p>
+           </item>
 
            <item>
              <p>when none of the above rules apply.</p>
                If you have to print a message that doesn't fit into
                the styles described above, you can use something
                appropriate, but please have a look at the overall
-               rules listed above.</p></item>
-         </list></p></sect>
-
+               rules listed above.
+             </p>
+           </item>
+         </list>
+       </p>
+      </sect>
 
       <sect>
        <heading>Menus</heading>
          Here is an example of a wrapper script for this purpose:
 
          <example>
-           #!/bin/sh
-           BAR=${BAR:-/var/lib/fubar}
-           export BAR
-           exec /usr/lib/foo/foo "$@"
+#!/bin/sh
+BAR=${BAR:-/var/lib/fubar}
+export BAR
+exec /usr/lib/foo/foo "$@"
          </example></p>
 
        <p>
        <p>
          Generally the following compilation parameters should be used:
          <example>
-           CC = gcc
-           CFLAGS = -O2 -Wall # sane warning options vary between programs
-           LDFLAGS = # none
-           install -s # (or use strip on the files in debian/tmp)
+CC = gcc
+CFLAGS = -O2 -Wall # sane warning options vary between programs
+LDFLAGS = # none
+install -s # (or use strip on the files in debian/tmp)
          </example></p>
 
        <p>
 
 
          <example>
-           CFLAGS = -O2 -Wall
-           INSTALL = install
-            INSTALL_FILE    = $(INSTALL) -p    -o root -g root  -m  644
-            INSTALL_PROGRAM = $(INSTALL) -p    -o root -g root  -m  755
-           INSTALL_SCRIPT  = $(INSTALL) -p    -o root -g root  -m  755
-            INSTALL_DIR     = $(INSTALL) -p -d -o root -g root  -m  755
-
-           ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
-           CFLAGS += -g
-           endif
-           ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
-           INSTALL_PROGRAM += -s
-           endif
+CFLAGS = -O2 -Wall
+INSTALL = install
+INSTALL_FILE    = $(INSTALL) -p    -o root -g root  -m  644
+INSTALL_PROGRAM = $(INSTALL) -p    -o root -g root  -m  755
+INSTALL_SCRIPT  = $(INSTALL) -p    -o root -g root  -m  755
+INSTALL_DIR     = $(INSTALL) -p -d -o root -g root  -m  755
+
+ifneq (,$(findstring debug,$(DEB_BUILD_OPTIONS)))
+CFLAGS += -g
+endif
+ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
+INSTALL_PROGRAM += -s
+endif
          </example>
 
          Please note that the above example is merely informative,
          Note that all installed shared libraries should be
          stripped with
          <example>
-           strip --strip-unneeded &lt;your-lib&gt;
+strip --strip-unneeded &lt;your-lib&gt;
          </example>
          (The option `--strip-unneeded' makes <tt>strip</tt> remove
          only the symbols which aren't needed for relocation
 
        <p>
          You should follow the directions in the <em>Debian Packaging
-           Manual</em> for putting the shared library in its package,
-         and you must include a <tt>shlibs</tt> control area
-         file with details of the dependencies for packages which
-         use the library.</p>
+           Manual</em> (or other documentation of the Debian
+         packaging tools) for putting the shared library in its
+         package, and you must include a <tt>shlibs</tt> control area
+         file with details of the dependencies for packages which use
+         the library.</p>
 
        <p>
          Shared libraries should not be installed
          For example, in your <prgn>Makefile</prgn> or
          <tt>debian/rules</tt>, do things like:
          <example>
-           ln -fs gcc $(prefix)/bin/cc
-           ln -fs gcc debian/tmp/usr/bin/cc
-           ln -fs ../sbin/sendmail $(prefix)/bin/runq
-           ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
+ln -fs gcc $(prefix)/bin/cc
+ln -fs gcc debian/tmp/usr/bin/cc
+ln -fs ../sbin/sendmail $(prefix)/bin/runq
+ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
          </example></p>
 
        <p>
          file (for more information see <manref name="logrotate"
                                                 section="8">):
          <example>
-           /var/log/foo/* {
-           rotate 12
-           weekly
-           compress
-           postrotate
-           /etc/init.d/foo force-reload
-           endscript
-           }
+/var/log/foo/* {
+rotate 12
+weekly
+compress
+postrotate
+/etc/init.d/foo force-reload
+endscript
+}
          </example>
          Which rotates all files under `/var/log/foo', saves 12
          compressed generations, and sends a HUP signal at the end of
       </sect>
     </chapt>
 
-    <chapt>
+    <chapt id="customized-programs">
       <heading>Customized programs</heading>
 
       <sect id="arch-spec">
          If a program needs to specify an <em>architecture specification
            string</em> in some place, the following format should be used:
          <example>
-           &lt;arch&gt;-&lt;os&gt;
+&lt;arch&gt;-&lt;os&gt;
          </example>
          where `&lt;arch&gt;' is one of the following: i386, alpha, arm, m68k,
          powerpc, sparc and `&lt;os&gt;' is one of: linux, gnu.  Use
              <p>Cgi-bin executable files are installed in the
                directory
                <example>
-                 /usr/lib/cgi-bin/&lt;cgi-bin-name&gt;
+/usr/lib/cgi-bin/&lt;cgi-bin-name&gt;
                </example>
                and should be referred to as
                <example>
-                 http://localhost/cgi-bin/&lt;cgi-bin-name&gt;
-               </example></p></item>
-
+http://localhost/cgi-bin/&lt;cgi-bin-name&gt;
+               </example>
+             </p>
+           </item>
 
            <item><p>Access to html documents</p>
 
                    backward compatibility, see <ref id="usrdoc"></footnote>
                and can be referred to as
                <example>
-                 http://localhost/doc/&lt;package&gt;/&lt;filename&gt;
-               </example></p></item>
-
+http://localhost/doc/&lt;package&gt;/&lt;filename&gt;
+               </example>
+             </p>
+           </item>
 
            <item><p>Web Document Root</p>
 
                register the Web Application via the menu package. If
                access to the web-root is unavoidable then use
                <example>
-                 /var/www
+/var/www
                </example>
                as the Document Root. This might be just a
                symbolic link to the location where the sysadmin has
          </enumlist></p></sect>
 
 
-      <sect>
+      <sect id="mail-transport-agents">
        <heading>Mail transport, delivery and user agents</heading>
 
        <p>
          serious brain damage!</p>
 
        <p>
-         The mail spool is <tt>/var/spool/mail</tt> and the interface
+         The mail spool is <tt>/var/mail</tt> and the interface
          to send a mail message is <tt>/usr/sbin/sendmail</tt> (as
-         per the FHS).  The mail spool is part of the base system
-         and not part of the MTA package.</p>
+         per the FHS).  On older systems, the mail spool may be
+         physically located in /var/spool/mail, but all access to the
+         mail spool should be via the /var/mail symlink. The mail
+         spool is part of the base system and not part of the MTA
+         package.
+       </p> 
 
        <p>
          All Debian MUAs, MTAs, MDAs and other mailbox accessing
          name will not just be used by that package.  For example, in
          this situation the INN package says:
          <example>
-           Please enter the `mail name' of your system.  This is the
-           hostname portion of the address to be shown on outgoing
-           news and mail messages.  The default is
-           <var>syshostname</var>, your system's host name.  Mail
-           name [`<var>syshostname</var>']:
+Please enter the `mail name' of your system.  This is the
+hostname portion of the address to be shown on outgoing
+news and mail messages.  The default is
+<var>syshostname</var>, your system's host name.  Mail
+name [`<var>syshostname</var>']:
          </example>
          where <var>syshostname</var> is the output of <tt>hostname
-           --fqdn</tt>.</p></sect>
-
+           --fqdn</tt>.
+       </p>
+      </sect>
 
       <sect>
        <heading>News system configuration</heading>
            <item>
                BDF fonts should be converted to PCF fonts with the
                <tt>bdftopcf</tt> utility (available in the
-               <tt>xutils</tt> package, <tt>gzip</tt>ped, and
+               <tt>xutils</tt> package), <tt>gzip</tt>ped, and
                placed in a directory that corresponds to their
                resolution:
                <list>
        </p>
       </sect>
 
+      <sect>
+       <heading>Perl programs and modules</heading>
+       <p>
+         Perl programs and modules should follow the current Perl             
+          policy as defined in the file found on                               
+         <ftpsite>ftp.debian.org</ftpsite> in                                 
+         <ftppath>/debian/doc/package-developer/perl-policy.txt.gz</ftppath>  
+         or your local mirror.  In addition, it is included in the            
+         <tt>debian-policy</tt> package.                                
+       </p>
+      </sect>
 
       <sect>
        <heading>Emacs lisp programs</heading>
          may be provided.  This symbolic link can be created from
          <tt>debian/rules</tt> like this:
          <example>
-           ln -s ../man7/undocumented.7.gz \
-           debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
+ln -s ../man7/undocumented.7.gz \
+debian/tmp/usr/share/man/man[1-9]/the_requested_manpage.[1-9].gz
          </example>
          This manpage claims that the lack of a manpage has been
          reported as a bug, so you may only do this if it really has
          <tt>dir</tt>
          file, in its post-installation script:
          <example>
-           install-info --quiet --section Development Development \
-           /usr/share/info/foobar.info
+install-info --quiet --section Development Development \
+/usr/share/info/foobar.info
          </example></p>
 
        <p>
        <p>
          You should remove the entries in the pre-removal script:
          <example>
-           install-info --quiet --remove /usr/share/info/foobar.info
+install-info --quiet --remove /usr/share/info/foobar.info
          </example></p>
 
        <p>
          this is to put the following in the package's
          <prgn>postinst</prgn>:
           <example>
-           if [ "$1" = "configure" ]; then
-           if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
-            -a -d /usr/share/doc/#PACKAGE# ]; then
-           ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
-           fi
-           fi
+if [ "$1" = "configure" ]; then
+  if [ -d /usr/doc -a ! -e /usr/doc/#PACKAGE# \
+       -a -d /usr/share/doc/#PACKAGE# ]; then
+    ln -sf ../share/doc/#PACKAGE# /usr/doc/#PACKAGE#
+  fi
+fi
           </example>
           And the following in the package's <prgn>prerm</prgn>:
           <example>
-           if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
-           -a -L /usr/doc/#PACKAGE# ]; then
-           rm -f /usr/doc/#PACKAGE#
-           fi
+if [ \( "$1" = "upgrade" -o "$1" = "remove" \) \
+     -a -L /usr/doc/#PACKAGE# ]; then
+  rm -f /usr/doc/#PACKAGE#
+fi
           </example>
        </p>
       </sect>
        <p>
          Every package must be accompanied by a verbatim copy of its
          copyright and distribution license in the file
-         /usr/share/doc/&lt;package-name&gt;/copyright. This file must
+         /usr/share/doc/&lt;package&gt;/copyright. This file must
          neither be compressed nor be a symbolic link.</p>
 
        <p>
 
 
        <p>
-         /usr/share/doc/&lt;package-name&gt; may be a symbolic link to a
+         /usr/share/doc/&lt;package&gt; may be a symbolic link to a
          directory in /usr/share/doc only if two packages both come from
          the same source and the first package has a "Depends"
          relationship on the second.  These rules are important