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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<title>debtree - Package dependency graphs</title>
</head>

<body>
<h1>debtree &mdash; package dependency graphs on steroids</h1>

<table>
<tbody valign="top">
<tr>
<td>
<h3><a href="index.html">Introduction</a></h3>

<h3>Advanced usage examples</h3>

<ol>
<li><a href="usage1.html">Create a build dependency graph</a></li>
<li><a href="usage2.html">Visualize what would happen when installing a package</a></li>
<li><b>Dependencies on virtual packages</b></li>
<li><a href="usage4.html">Reverse dependencies</a></li>
</ol>
<hr />

<p>
The top graph for <tt>pident</tt> incudes three dependencies on virtual
packages and shows how virtual packages and the packages that provide
them can be displayed.
</p><p>
The first is a fairly common dependency on <tt>debconf | debconf-2.0</tt>
where the latter is a virtual package provided by either <tt>debconf</tt>
or <tt>cdebconf</tt>. <tt>debconf</tt> has square brackets because it is
also included in the alternative dependencies; <tt>cdebconf</tt> has curly
brackets because its dependencies are not included anywhere in the graph.
</p><p>
The second is the virtual package <tt>inet-superserver</tt>. Because the
maximum number of providers was set to 5 and there are 4 packages that
actually provide this virtual package, all providing packages are shown.
<tt>openbsd-inetd</tt> has square brackets because it was also displayed
as the preferred alternative; for the others no dependencies are shown
and thus their names have curly brackets.
</p><p>
The third is the virtual package <tt>ident-server</tt>. There are 7 packages
that provide this virtual package, which is more than the maximum that was
set. Therefore no individual providing packages are shown, but the total
number of providing packages is shown alongside the arrow for the
relationship. Note that the requested package <tt>pidentd</tt> is one of
the providing package.
</p><p>
Adding the option <tt>-I</tt> (show installed packages) when generating this
graph, could result in the bottom graph, which has the following changes:
</p>
<ul>
<li>
as <tt>debconf</tt> is installed, <tt>debconf-2.0</tt> is no longer
shown and thus the providing packages are not shown either; the ellipsis in
the second row indicates there are other packages that can satisfy the
alternative dependency
</li><li>
as <tt>openbsd-inetd</tt> is installed, only that providing package is shown
as alternative and thus again <tt>inet-superserver</tt> and its providing
packages are no longer included
</li><li>
as <tt>pidentd</tt> is installed, only that providing package is shown for
<tt>ident-server</tt>; as <tt>ident-server</tt> is provided by the requested
package, this virtual package is still shown; the ellipsis in the second row
indicates there are other (undisplayed) providing packages
</li>
</ul>

<p>Note that for this second graph the option <tt>--max-providers<tt> is no
longer relevant.</p>

</td>
<td width="10" />
<td width="400">

<p><tt><font size="-1">
$ debtree --max-providers=5 pident
</font></tt></p>
<hr />
<img src="thumbs/usage3.1.png" alt="Dependency graph for pidentd" />
<hr />
<table>
<tr>
<td>Generated .dot file:</td>
<td><a href="usage3.1.dot">DOT</a></td>
</tr><tr>
<td>Full-sized images:</td>
<td><a href="usage3.1.ps" target="_blank">PS</a>&nbsp;|&nbsp;PNG&nbsp;|&nbsp;<a href="usage3.1.svg" target="_blank">SVG</a></td>
</tr>
</table>

<br />

<p><tt><font size="-1">
$ debtree -I pident
</font></tt></p>
<hr />
<img src="thumbs/usage3.2.png" alt="Dependency graph for pidentd (with installed packages)" />
<hr />
<table>
<tr>
<td>Generated .dot file:</td>
<td><a href="usage3.2.dot">DOT</a></td>
</tr><tr>
<td>Full-sized images:</td>
<td><a href="usage3.2.ps" target="_blank">PS</a>&nbsp;|&nbsp;PNG&nbsp;|&nbsp;<a href="usage3.2.svg" target="_blank">SVG</a></td>
</tr>
</table>

</td>
</tr>
</tbody>
</table>

</body>
</html>