Two new exercises mlocate / tail

Doc/Sdi/UnixIntro/unixIntro.xml

@@ -272,8 +272,8 @@ chmod go-r id_rsa <co linkends="sdi_fig_sshPermissions-7"
 
         <callout arearefs="sdi_fig_sshPermissions-6-co"
                  xml:id="sdi_fig_sshPermissions-6">
-          <para>Configuration files do not necessitate execution privileges.
-          </para>
+          <para>Configuration files do not necessitate execution
+          privileges.</para>
         </callout>
 
         <callout arearefs="sdi_fig_sshPermissions-7-co"
@@ -306,5 +306,86 @@ drwxr-xr-x+ 30 goik fb1prof    0 Oct 13 16:04 ..
       <screen>~&gt; ssh localhost
 Welcome to Ubuntu 18.04.3 LTS ...</screen>
     </figure>
+
+    <qandaset defaultlabel="qanda" xml:id="unixintro_qanda_mlocate">
+      <title>Enabling index based file search</title>
+
+      <qandadiv>
+        <qandaentry>
+          <question>
+            <itemizedlist>
+              <listitem>
+                <para>Install the <productname>mlocate</productname>
+                package.</para>
+              </listitem>
+
+              <listitem>
+                <para>Index your current file system using the
+                <command>updatedb</command> command</para>
+              </listitem>
+
+              <listitem>
+                <para>Use the <command>locate</command>
+                <option>aptitude</option> command to search for filenames
+                containing the string »<code>aptitude</code>«.</para>
+              </listitem>
+
+              <listitem>
+                <para>Create a new file
+                <filename>mylocaltest.txt</filename>.</para>
+              </listitem>
+
+              <listitem>
+                <para>Use <command>locate</command>
+                <option>localtest</option>. What do you observe?</para>
+              </listitem>
+
+              <listitem>
+                <para>Rebuild the index again.</para>
+              </listitem>
+
+              <listitem>
+                <para>Use <command>locate</command> again searching for files
+                containing the »<code>localtest</code>« string again.</para>
+              </listitem>
+            </itemizedlist>
+          </question>
+
+          <answer>
+            <para>The first <command>locate</command>
+            <option>localtest</option> call fails since the
+            <filename>mylocaltest.txt</filename> file is not part of the index
+            yet. After rebuilding it will be found.</para>
+          </answer>
+        </qandaentry>
+      </qandadiv>
+    </qandaset>
+
+    <qandaset defaultlabel="qanda" xml:id="unixintro_qanda_tail">
+      <title>Using the <command>tail</command> <option>-f</option>
+      command</title>
+
+      <qandadiv>
+        <qandaentry>
+          <question>
+            <itemizedlist>
+              <listitem>
+                <para>Login to your VM</para>
+              </listitem>
+
+              <listitem>
+                <para>Issue <command>tail</command> <option>-f</option>
+                <option>/var/log/auth.log</option>.</para>
+              </listitem>
+
+              <listitem>
+                <para>Ask your partner to log into the same VM and watch for
+                incoming changes.</para>
+              </listitem>
+            </itemizedlist>
+          </question>
+        </qandaentry>
+      </qandadiv>
+    </qandaset>
   </section>
 </chapter>