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<?xml version="1.0"?>
<article>
  <articleinfo>
    <title>DebianReference/SystemTips</title>
  </articleinfo>
  <para/>
  <section>
    <title>Do not use Edit(GUI) button.</title>
    <para> </para>
    <para>Copyright 2007, 2008  Osamu Aoki GPL, (Please agree to GPL, GPL2, and any version of GPL which is compatible with DSFG if you update any part of wiki page) </para>
    <para>Generated HTML is at "<ulink url="http://people.debian.org/~osamu/pub/getwiki/html/ch10.en.html">Debian Reference: Chapter 10. System tips</ulink>". </para>
    <para>I welcome your contributions to update this wiki page. You must follow these rules: </para>
    <itemizedlist>
      <listitem>
        <para>Do not use Edit(GUI) button of <ulink url="/MoinMoin">MoinMoin</ulink>. </para>
      </listitem>
      <listitem>You can update anytime for: <itemizedlist><listitem>grammar errors </listitem><listitem>spelling errors </listitem><listitem>moved URL location </listitem><listitem>package name transition adjustment (emacs23 etc.) </listitem><listitem>clearly broken script. </listitem></itemizedlist></listitem>
      <listitem>Before updating this wiki content: <itemizedlist><listitem><para>Read "<ulink url="http://wiki.debian.org/DebianReference/Test">Guide for contributing to Debian Reference</ulink>". </para></listitem></itemizedlist></listitem>
    </itemizedlist>
    <para/>
  </section>
  <section>
    <title>System tips</title>
    <para>Here, I will describe basic tips to configure and manage systems, mostly from the console.   </para>
    <para/>
    <section>
      <title>The screen program</title>
      <para>The <code>screen</code> program is a very useful tool for people to access remote sites via unreliable or intermittent connections since it support interrupted network connections. </para>
      <table>
        <caption/>
        <tgroup cols="4">
          <colspec colname="xxx1"/>
          <colspec colname="xxx2"/>
          <colspec colname="xxx3"/>
          <colspec colname="xxx4"/>
          <tbody>
            <row>
              <entry>
                <para> List of programs to support interrupted network connections. </para>
              </entry>
              <entry>
                <para> 1 </para>
              </entry>
              <entry>
                <para> 2 </para>
              </entry>
              <entry>
                <para> 3 </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <emphasis role="strong">package</emphasis>
                </para>
              </entry>
              <entry>
                <para>
                  <emphasis role="strong">popcon</emphasis>
                </para>
              </entry>
              <entry>
                <para>
                  <emphasis role="strong">size</emphasis>
                </para>
              </entry>
              <entry>
                <para>
                  <emphasis role="strong">description</emphasis>
                </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>screen</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> terminal multiplexer with VT100/ANSI terminal emulation </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>xmove</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> allows you to move programs between X Window System displays </para>
              </entry>
            </row>
          </tbody>
        </tgroup>
      </table>
      <para/>
      <section>
        <title>The use scenario for the screen command</title>
        <para>The <code>screen</code>(1) program not only allows one terminal window to work with multiple processes, but also allows <emphasis role="strong">remote shell process to survive interrupted connections</emphasis>.  Here is a typical use scenario of the <code>screen</code>(1) program. </para>
        <orderedlist numeration="arabic">
          <listitem>You login to a remote machine. </listitem>
          <listitem>
            <para>You start the <code>screen</code> command on a single console. </para>
          </listitem>
          <listitem>
            <para>You execute multiple programs in <code>screen</code> windows created with <code>^A c</code> ("Control-A" followed by "c"). </para>
          </listitem>
          <listitem>
            <para>You switch among the multiple <code>screen</code> windows by <code>^A n</code> ("Control-A" followed by "n"). </para>
          </listitem>
          <listitem>Suddenly you need to leave your terminal, but you don't want to lose your active work by keeping the connection. </listitem>
          <listitem>
            <para>You <emphasis role="strong">detach</emphasis> the <code>screen</code> session by any methods such as: </para>
            <itemizedlist>
              <listitem>brutally unplugging your network connection, </listitem>
              <listitem>
                <para>typing <code>^A d</code> ("Control-A" followed by "d") and manually logging out from the remote connection, or </para>
              </listitem>
              <listitem>
                <para>typing <code>^A DD</code> ("Control-A" followed by "DD") to have <code>screen</code> detach and log you out. </para>
              </listitem>
            </itemizedlist>
          </listitem>
          <listitem>You log in again to the same remote machine (even from a different terminal). </listitem>
          <listitem>
            <para>You enter the "<code>screen -r</code>" command. </para>
          </listitem>
          <listitem>
            <para>The <code>screen</code> program will magically <emphasis role="strong">reattach</emphasis> all previous <code>screen</code> windows with all actively running programs. </para>
          </listitem>
        </orderedlist>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> You can save connection fees for metered network connections such as dial-up and packet ones, because you can leave a process active while disconnected, and then re-attach it later when you connect again. </para>
        <para/>
      </section>
      <section>
        <title>Key bindings for the screen command</title>
        <para>In <code>screen</code> session, all keyboard inputs are sent to your current window except for the command keystroke, by default <code>^A</code> ("Control-A").  All <code>screen</code> commands are entered by typing <code>^A</code> plus a single key [plus any parameters].  Here are important ones to remember: </para>
        <table>
          <caption/>
          <tgroup cols="2">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <tbody>
              <row>
                <entry>
                  <para> List of key bindings for screen. </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">key binding</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">meaning</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A ?</code>
                  </para>
                </entry>
                <entry>
                  <para> show a help screen (display key bindings) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A c</code>
                  </para>
                </entry>
                <entry>
                  <para> create a new window and switch to it </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A n</code>
                  </para>
                </entry>
                <entry>
                  <para> go to next window </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A p</code>
                  </para>
                </entry>
                <entry>
                  <para> go to previous window </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A 0</code>
                  </para>
                </entry>
                <entry>
                  <para> go to window number 0 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A 1</code>
                  </para>
                </entry>
                <entry>
                  <para> go to window number 1 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A w</code>
                  </para>
                </entry>
                <entry>
                  <para> show a list of windows </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A a</code>
                  </para>
                </entry>
                <entry>
                  <para> send a Ctrl-A to current window as keyboard input </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A h</code>
                  </para>
                </entry>
                <entry>
                  <para> write a hardcopy of current window to file </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A H</code>
                  </para>
                </entry>
                <entry>
                  <para> begin/end logging current window to file </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A ^X</code>
                  </para>
                </entry>
                <entry>
                  <para> lock the terminal (password protected) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A d</code>
                  </para>
                </entry>
                <entry>
                  <para> detach screen session from the terminal </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>^A DD</code>
                  </para>
                </entry>
                <entry>
                  <para> detach screen session and log out </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para>See <code>screen</code>(1) for details. </para>
        <para/>
      </section>
      <section>
        <title>A screen-like program for X window system</title>
        <para>The <code>xmove</code> package enables support for mobile X clients; that is, X clients can move between displays.  See <code>xmove</code>(1). </para>
        <para/>
      </section>
    </section>
    <section>
      <title>Data recording and presentation</title>
      <para/>
      <section>
        <title>The log daemon</title>
        <para>Many programs record their activities under the <code>/var/log/</code> directory. </para>
        <itemizedlist>
          <listitem>
            <para>The kernel log daemon: <code>klogd</code>(8) </para>
          </listitem>
          <listitem>
            <para>The system log daemon: <code>syslogd</code>(8) </para>
          </listitem>
        </itemizedlist>
        <para>See @{@thesystemmessage@}@ and @{@thekernelmessage@}@. </para>
        <para/>
      </section>
      <section>
        <title>Log analyzer</title>
        <para>Here are notable log analyzers ("<code>~Gsecurity::log-analyzer</code>" in <code>aptitude</code>). </para>
        <table>
          <caption/>
          <tgroup cols="4">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <tbody>
              <row>
                <entry>
                  <para> List of system log analyzers. </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">popcon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">description</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>logwatch</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para>log analyser with nice output written in Perl  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>fail2ban</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> bans IPs that cause multiple authentication errors </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>analog</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> web server log analyzer </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>awstats</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para>  powerful and featureful web server log analyzer</para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>sarg</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> squid analysis report generator </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>pflogsumm</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Postfix log entry summarizer </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>syslog-summary</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> summarize the contents of a syslog log file </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>lire</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> full-featured log analyzer and report generator </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>fwlogwatch</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Firewall log analyzer </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>squidview</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> monitors and analyses squid access.log files </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>visitors</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> fast web server log analyzer </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>swatch</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Log file viewer with regexp matching, highlighting, &amp; hooks </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>crm114</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> The Controllable Regex Mutilator and Spam Filter (CRM114) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>icmpinfo</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Interpret ICMP messages </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/idea.png" depth="15"/></imageobject><textobject><phrase>(!)</phrase></textobject></inlinemediaobject><ulink url="http://crm114.sourceforge.net/">CRM114</ulink> provides language infrastructure to write <emphasis role="strong">fuzzy</emphasis> filters with the <ulink url="http://www.laurikari.net/tre/">TRE regex library</ulink>.  Its popular use is spam mail filter but it can be used as log analyzer. </para>
        <para/>
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      </section>
      <section>
        <title>Recording the shell activities cleanly</title>
        <para>The simple use of the <code>script</code>(1) command (see: @{@recordingtheshellactivities@}@) to record shell activity produces a file with control characters.  This can be avoided by using the <code>col</code>(1) command: </para>
        <screen><![CDATA[$ script
Script started, file is typescript
]]></screen>
        <itemizedlist>
          <listitem>do whatever ... </listitem>
          <listitem>
            <para>Press <code>Ctrl-D</code> to exit <code>script</code> </para>
          </listitem>
        </itemizedlist>
        <para/>
        <screen><![CDATA[$ col -bx <typescript >cleanedfile
$ vim cleanedfile
]]></screen>
        <para>If you don't have the <code>script</code> command (for example, during the boot process in the initramfs), you can use following instead: </para>
        <screen><![CDATA[$ sh -i 2>&1 | tee typescript
]]></screen>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> Some <code>x-terminal-emulator</code> such as <code>gnome-terminal</code> can record.  You may wish to extend line buffer for scrollback.  </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> You may use <code>screen</code> command with "<code>^A H</code>" (see @{@keybindingsforthescreencommand@}@) to perform recording of console.   </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> You may use <code>emacs</code>  with "<code>M-x shell</code>", "<code>M-x eshell</code>", or "<code>M-x term</code>" to perform recording of console.  You may later use "<code>C-x C-w</code>" to write the buffer to a file. </para>
        <para/>
      </section>
      <section>
        <title>Customized display of text data</title>
        <para>Although pager tools such as <code>more</code>(1) and <code>less</code>(1) (see @{@thepager@}@) and custom tools for highlighting and formatting @{@highlightingandfingplaintextdata@}@ can display text data nicely, general purpose editors (see @{@thetexteditor@}@) are most versatile and customizable. </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> For <code>vim</code>(1) and its pager mode alias <code>view</code>(1), "<code>:set hls</code>" will enable highlighted search. </para>
        <para/>
      </section>
      <section>
        <title>Colorized shell echo</title>
        <para>Shell echo to most modern terminals can be colorized using <ulink url="http://en.wikipedia.org/wiki/ANSI_escape_code">ANSI escape code</ulink> (see <code>/usr/share/doc/xterm/ctlseqs.txt.gz</code>).  E.g.: </para>
        <screen><![CDATA[$ RED=$(printf "\x1b[31m")
$ NORMAL=$(printf "\x1b[0m")
$ REVERSE=$(printf "\x1b[7m")
$ echo "${RED}RED-TEXT${NORMAL} ${REVERSE}REVERSE-TEXT${NORMAL}"
]]></screen>
        <para/>
        <para/>
      </section>
      <section>
        <title>Colorized commands</title>
        <para>Colorized commands are handy for inspecting their output in the interactive environment.  I include following in my <code>~/.bashrc</code>. </para>
        <screen><![CDATA[if [ "$TERM" != "dumb" ]; then
    eval "`dircolors -b`"
    alias ls='ls --color=always'
    alias ll='ls --color=always -l'
    alias la='ls --color=always -A'
    alias less='less -R'
    alias ls='ls --color=always'
    alias grep='grep --color=always'
    alias egrep='egrep --color=always'
    alias fgrep='fgrep --color=always'
    alias zgrep='zgrep --color=always'
else
    alias ll='ls -l'
    alias la='ls -A'
fi
]]></screen>
        <para>The use of alias limits color effects to the interactive command usage.  It has advantage over exporting environment variable "<code>export GREP_OPTIONS='--color=auto'</code>" since color can be seen under pager programs such as "<code>less</code>". </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> You can turn off these colorizing aliases in the interactive environment by invoking shell with "<code>TERM=dumb bash</code>". </para>
        <para/>
      </section>
      <section>
        <title>Recording the graphic image of an X application</title>
        <para>There are few ways to record the graphic image of an X application, including an <code>xterm</code> display. </para>
        <table>
          <caption/>
          <tgroup cols="4">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <tbody>
              <row>
                <entry>
                  <para> List of graphic image manipulation tools. </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">popcon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">command</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>xbase-clients</code>
                  </para>
                </entry>
                <entry>
                  <para>  25829 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><code>xwd</code>(1) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>gimp</code>
                  </para>
                </entry>
                <entry>
                  <para> 8489 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> GUI menu  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>imagemagick</code>
                  </para>
                </entry>
                <entry>
                  <para> 5479 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><code>import</code>(1) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>scrot</code>
                  </para>
                </entry>
                <entry>
                  <para> 134 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><code>scrot</code>(1) </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para/>
      </section>
      <section>
        <title>Recording changes in configuration files</title>
        <para>There are specialized tools to record changes in configuration files with help of DVCS system. </para>
        <table>
          <caption/>
          <tgroup cols="4">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <tbody>
              <row>
                <entry>
                  <para> List of packages to record configuration history in VCS. </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">popcon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">description</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>etckeeper</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> store configuration files and its metadata with <ulink url="http://en.wikipedia.org/wiki/Git_(software)">Git</ulink> (default), <ulink url="http://en.wikipedia.org/wiki/Mercurial_(software)">Mercurial</ulink>, or <ulink url="http://en.wikipedia.org/wiki/Bazaar_(software)">Bazaar</ulink>. (new) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>changetrack</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> store configuration files with <ulink url="http://en.wikipedia.org/wiki/Revision_Control_System">RCS</ulink>. (old)  </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para>I recommend to use the <code>etckeeper</code> package with <code>git</code>(1) which put entire "<code>/etc</code>" under VCS control.  Its installation guide and tutorial are found in "<code>/usr/share/doc/etckeeper/README.gz</code>".   </para>
        <para>Essentially, running "<code>sudo etckeeper init</code>" initializes the git repository for "<code>/etc</code>" just like the process explained in @{@gitforrecordingcigurationhistory@}@) but with special hook scripts for more thorough setups.   </para>
        <para>As you change your configuration, you can use <code>git</code>(1) normally to record them.  It will automatically record changes nicely every time you run package management commands, too. </para>
        <para>You can browse history of "<code>/etc</code>" and package upgrade by executing "<code>cd /etc; sudo gitk</code>". </para>
        <para/>
      </section>
    </section>
    <section>
      <title>Data storage tips</title>
      <para>Booting your system with Linux <ulink url="http://en.wikipedia.org/wiki/Live_CD">live CDs</ulink> or <ulink url="http://www.debian.org/releases/stable/debian-installer/">debian-installer CDs</ulink> in rescue mode make it easy for you to reconfigure data storage on your boot device.  See also @{@thebinarydata@}@. </para>
      <para/>
      <section>
        <title>Partition configuration</title>
        <para>For partition configuration, although <code>fdisk</code>(8) has been considered standard, <code>parted</code>(8) deserves some attention.  "Disk partitioning data", "partition table", "partition map", and "disk label" are all synonyms. </para>
        <para>Most PCs use the classic <ulink url="http://en.wikipedia.org/wiki/Master_boot_record">Master Boot Record (MBR)</ulink> scheme to hold <ulink url="http://en.wikipedia.org/wiki/Disk_partitioning">disk partitioning</ulink> data in the first sector, i.e., <ulink url="http://en.wikipedia.org/wiki/Logical_block_addressing">LBA</ulink> sector 0 (512 bytes). </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/idea.png" depth="15"/></imageobject><textobject><phrase>(!)</phrase></textobject></inlinemediaobject> Some new PCs with <ulink url="http://en.wikipedia.org/wiki/Extensible_Firmware_Interface">Extensible Firmware Interface (EFI)</ulink>, including Intel-based Macs, use <ulink url="http://en.wikipedia.org/wiki/GUID_Partition_Table">GUID Partition Table (GPT)</ulink> scheme to hold <ulink url="http://en.wikipedia.org/wiki/Disk_partitioning">disk partitioning</ulink> data not in the first sector. </para>
        <para>Although <code>fdisk</code>(8) has been standard for the disk partitioning tool, <code>parted</code>(8) is replacing it. </para>
        <table>
          <caption/>
          <tgroup cols="5">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <colspec colname="xxx5"/>
            <tbody>
              <row>
                <entry>
                  <para> List of disk partition management packages </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">pocon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">description</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <ulink url="http://en.wikipedia.org/wiki/GUID_Partition_Table">GUID Partition Table</ulink>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>util-linux</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Miscellaneous system utilities including <code>fdisk</code>(8) and <code>cfdisk</code>(8) </para>
                </entry>
                <entry>
                  <para> Not supported </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>parted</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> The GNU Parted disk partition resizing program </para>
                </entry>
                <entry>
                  <para> Supported </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>gparted</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> GNOME partition editor based on <code>libparted</code> </para>
                </entry>
                <entry>
                  <para> Supported </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>qtparted</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> KDE partition editor based on <code>libparted</code> </para>
                </entry>
                <entry>
                  <para> Supported </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>gptsync</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Synchronize classic MBR partition table with the GPT one </para>
                </entry>
                <entry>
                  <para> Supported </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para/>
        <para/>
        <para/>
        <para/>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> Although <code>parted</code>(8) claims to create and to resize filesystem too, it is safer to do such things using best maintained specialized tools such as <code>mkfs</code>(8) (<code>mkfs.msdos</code>(8), <code>mkfs.ext2</code>(8), <code>mkfs.ext3</code>(8), ...) and <code>resize2fs</code>(8). </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/idea.png" depth="15"/></imageobject><textobject><phrase>(!)</phrase></textobject></inlinemediaobject> In order to switch between GPT and MBR, you need to erase first few blocks of disk contents directly (see @{@clearfilecontents@}@) and use "<code>parted /dev/sdx mklabel gpt</code>" or "<code>parted /dev/sdx mklabel msdos</code>" to set it.  Please note "msdos" is use here for MBR. </para>
        <para/>
      </section>
      <section>
        <title>Accessing partition using UUID</title>
        <para>Although reconfiguration of your partition may yield different names for partitions, you can access them consistently. This is also helpful if you have multiple disks and your BIOS doesn't give them consistent device names. </para>
        <itemizedlist>
          <listitem>
            <para>The <code>mount</code>(8) command with "<code>-U</code>" options can mount a block device using <ulink url="http://en.wikipedia.org/wiki/Universally_Unique_Identifier">UUID</ulink>, instead of using its file name such as "<code>/dev/sda3</code>".   </para>
          </listitem>
          <listitem>
            <para>The "<code>/etc/fstab</code>" file (see <code>fstab</code>(5)) can use <ulink url="http://en.wikipedia.org/wiki/Universally_Unique_Identifier">UUID</ulink>. </para>
          </listitem>
          <listitem>
            <para>Boot loaders (@{@stagecthebootloader@}@) may use <ulink url="http://en.wikipedia.org/wiki/Universally_Unique_Identifier">UUID</ulink> too. </para>
          </listitem>
        </itemizedlist>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> You can probe <ulink url="http://en.wikipedia.org/wiki/Universally_Unique_Identifier">UUID</ulink> of a block special device with the <code>vol_id</code>(8) command.  </para>
        <para/>
      </section>
      <section>
        <title>Filesystem configuration</title>
        <para>For <ulink url="http://en.wikipedia.org/wiki/Ext3">ext3</ulink> filesystem, the <code>e2fsprogs</code> package provides: </para>
        <itemizedlist>
          <listitem>
            <para><code>mkfs.ext3</code>(8) to create new <ulink url="http://en.wikipedia.org/wiki/Ext3">ext3</ulink> filesystem, </para>
          </listitem>
          <listitem>
            <para><code>fsck.ext3</code>(8) to check and to repair existing <ulink url="http://en.wikipedia.org/wiki/Ext3">ext3</ulink> filesystem, and </para>
          </listitem>
          <listitem>
            <para><code>tune2fs</code>(8) to configure superblock of <ulink url="http://en.wikipedia.org/wiki/Ext3">ext3</ulink> filesystem. </para>
          </listitem>
        </itemizedlist>
        <para>The <code>mkfs</code>(8) and <code>fsck</code>(8) commans are provided by the <code>e2fsprogs</code> package as front-ends to various filesystem dependent programs (<code>mkfs.fstype</code> and <code>fsck.fstype</code>). For <ulink url="http://en.wikipedia.org/wiki/Ext3">ext3</ulink> filesystem, they are <code>mkfs.ext3</code>(8) and <code>fsck.ext3</code>(8) (they are hardlinked to <code>mke2fs</code>(8) and <code>e2fsck</code>(8)). </para>
        <para>Similar commands are available for each filesystem supported by Linux. </para>
        <table>
          <caption/>
          <tgroup cols="4">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <tbody>
              <row>
                <entry>
                  <para> List of filesystem management packages </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">popcon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">description</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>e2fsprogs</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for the <ulink url="http://en.wikipedia.org/wiki/Ext2">ext2</ulink>/<ulink url="http://en.wikipedia.org/wiki/Ext3">ext3</ulink>/<ulink url="http://en.wikipedia.org/wiki/Ext4">ext4</ulink> filesystems. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>reiserfsprogs</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for the <ulink url="http://en.wikipedia.org/wiki/Reiserfs">Reiserfs</ulink> filesystem. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>dosfstools</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for the <ulink url="http://en.wikipedia.org/wiki/File_Allocation_Table">FAT</ulink> filesystem. (Microsoft: MS-DOS, Windows) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>xfsprogs</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for the <ulink url="http://en.wikipedia.org/wiki/XFS">XFS</ulink> filesystem. (SGI: IRIX) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>ntfsprogs</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for the <ulink url="http://en.wikipedia.org/wiki/NTFS">NTFS</ulink> filesystem. (Microsoft: Windows NT, ...) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>jfsutils</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for the <ulink url="http://en.wikipedia.org/wiki/JFS_(file_system)">JFS</ulink> filesystem. (IBM: AIX, OS/2) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>reiser4progs</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for the <ulink url="http://en.wikipedia.org/wiki/Reiser4">Reiser4</ulink> filesystem. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>hfsprogs</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for <ulink url="http://en.wikipedia.org/wiki/Hierarchical_File_System">HFS</ulink> and <ulink url="http://en.wikipedia.org/wiki/HFS_Plus">HFS+</ulink> filesystem. (Apple: Mac OS) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>btrfs-tools</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for the <ulink url="http://en.wikipedia.org/wiki/Btrfs">btrfs</ulink> filesystem. </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject><ulink url="http://en.wikipedia.org/wiki/Ext3">Ext3</ulink> filesystem is the default filesystem for the Linux system and strongly recommended to use it unless you have some specific reasons not to.  After Linux kernel 2.6.28 (Debian <code>squeeze</code>), <ulink url="http://en.wikipedia.org/wiki/Ext4">ext4</ulink> filesystem will be available and expected to be the default filesystem for the Linux system.  <ulink url="http://en.wikipedia.org/wiki/Btrfs">btrfs</ulink> filesystem is expected to be the next default filesystem after <ulink url="http://en.wikipedia.org/wiki/Ext4">ext4</ulink> filesystem for the Linux system. </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> Some tools allow access to filesystem without Linux kernel support (see @{@manipulatingfilehoutmountingdisk@}@). </para>
        <para/>
      </section>
      <section>
        <title>Filesystem creation and integrity check</title>
        <para>The <code>mkfs</code>(8) command creates the filesystem on a Linux system. The <code>fsck</code>(8) command provides the filesystem integrity check and repair on a Linux system.   </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> Check files in <code>/var/log/fsck/</code> for the result of the <code>fsck</code>(8) command run from the boot script. </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> It is generally not safe to run <code>fsck</code> on mounted filesystems. </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> Use "<code>shutdown -F -r now</code>" to force to run the <code>fsck</code>(8) command safely on all filesystems including root file system on reboot. See the <code>shutdown</code>(8) manpage for more. </para>
        <para/>
      </section>
      <section>
        <title>Optimization of filesystem by mount options</title>
        <para>Performance and characteristics of a filesystem can be optimized by mount options used on it (see <code>fstab</code>(5) and <code>mount</code>(8)).  For example: </para>
        <itemizedlist>
          <listitem>
            <para>"<code>defaults</code>" option implies default options: "<code>rw,suid,dev,exec,auto,nouser,async</code>". (general) </para>
          </listitem>
          <listitem>
            <para>"<code>noatime</code>" or "<code>relatime</code>" option is very effective for speeding up the read access. (general) </para>
          </listitem>
          <listitem>
            <para>"<code>user</code>" option allows an ordinary user to mount the file system. This option implies "<code>noexec,nosuid,nodev</code>" option combination. (general, used for CD and floppy) </para>
          </listitem>
          <listitem>
            <para>"<code>noexec,nodev,nosuid</code>" option combination is used to enhance security. (general) </para>
          </listitem>
          <listitem>
            <para>"<code>noauto</code>" option limits mounting by explicit operation only. (general) </para>
          </listitem>
          <listitem>
            <para>"<code>data=journal</code>" option for ext3fs can enhance data integrity against power failure with some loss of write speed. </para>
          </listitem>
        </itemizedlist>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject>  You need to provide kernel boot parameter "<code>rootflags=data=journal</code>" to deploy "<code>data=journal</code>" option for the root file system formatted with ext3fs. </para>
        <para/>
      </section>
      <section>
        <title>Optimization of filesystem via superblock</title>
        <para>Characteristics of a filesystem can be optimized via its superblock using the <code>tune2fs</code>(8) command.  For example on <code>/dev/hda1</code>: </para>
        <itemizedlist>
          <listitem>
            <para>Execution of "<code>sudo tune2fs -l /dev/hda1</code>" will display the contents of its filesystem superblock. </para>
          </listitem>
          <listitem>
            <para>Execution of "<code>sudo tune2fs -c 50 /dev/hda1</code>" will change frequency of filesystem checks (<code>fsck</code> execution during boot-up) to every 50 boots. </para>
          </listitem>
          <listitem>
            <para>Execution of "<code>sudo tune2fs -j /dev/hda1</code>" will add journaling capability to the filesystem, i.e. filesystem conversion from <ulink url="http://en.wikipedia.org/wiki/Ext2">ext2</ulink> to <ulink url="http://en.wikipedia.org/wiki/Ext3">ext3</ulink>.  (Do this on the unmounted filesystem.) </para>
          </listitem>
          <listitem>
            <para>Execution of "<code>sudo tune2fs -O extents,uninit_bg,dir_index /dev/hda1 &amp;&amp; fsck -pf /dev/hda1</code>" will convert it from <ulink url="http://en.wikipedia.org/wiki/Ext3">ext3</ulink> to <ulink url="http://en.wikipedia.org/wiki/Ext4">ext4</ulink>.  (Do this on the unmounted filesystem.) </para>
          </listitem>
        </itemizedlist>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/alert.png" depth="15"/></imageobject><textobject><phrase>/!\</phrase></textobject></inlinemediaobject> Filesystem conversion for the boot device to the <ulink url="http://en.wikipedia.org/wiki/Ext4">ext4</ulink> filesystem should be avoided until <ulink url="http://bugs.debian.org/511121">GRUB boot loader supports the ext4 filesystem well</ulink> and installed Linux Kernel version is newer than 2.6.28. </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> Despite its name, <code>tune2fs</code>(8) works not only on the <ulink url="http://en.wikipedia.org/wiki/Ext2">ext2</ulink> filesystem but also on the <ulink url="http://en.wikipedia.org/wiki/Ext3">ext3</ulink> and <ulink url="http://en.wikipedia.org/wiki/Ext4">ext4</ulink> filesystems. </para>
        <para/>
      </section>
      <section>
        <title>Optimization of harddisk</title>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/alert.png" depth="15"/></imageobject><textobject><phrase>/!\</phrase></textobject></inlinemediaobject> Please check your hardware and read manpage of <code>hdparam</code>(8) before playing with harddisk configuration because this may be quite dangerous for the data integrity. </para>
        <para>You can test disk access speed of a harddisk, e.g. <code>/dev/hda</code>, by "<code>hdparm -tT /dev/hda</code>". For some harddisk connected with (E)IDE, you can speed it up with "<code>hdparm -q -c3 -d1 -u1 -m16 /dev/hda</code>" by enabling the "(E)IDE 32-bit I/O support", enabling the "using_dma flag", setting "interrupt-unmask flag", and setting the "multiple 16 sector I/O" (dangerous!). </para>
        <para>You can test write cache feature of a harddisk, e.g. <code>/dev/sda</code>, by "<code>hdparm -W /dev/sda</code>". You can disable its write cache feature with "<code>hdparm -W 0 /dev/sda</code>". </para>
        <para>You may be able to read badly pressed CDROMs on modern high head CD-ROM drive by slowing it down with "<code>setcd -x 2</code>. </para>
        <para/>
      </section>
      <section>
        <title>Expand usable storage space via LVM</title>
        <para>For partitions created on <ulink url="http://en.wikipedia.org/wiki/Logical_Volume_Manager_(Linux)">Logical Volume Manager (Linux)</ulink> at install time, they can be resized easily by concatenating extents onto them or truncating extents from them over multiple storage devices without major system reconfiguration. </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> Deployment of the current LVM system may degrade guarantee against filesystem corruption offered by journaled file systems such as ext3fs unless their system performance is sacrificed by disabling write cache of harddisk. </para>
        <para/>
      </section>
      <section>
        <title>Expand usable storage space by mounting another partition</title>
        <para>If you have an empty partition (e.g., <code>/dev/sdx</code>), you can format it with <code>mkfs.ext3</code>(1) and <code>mount</code>(8) it to a directory where you need more space. (You need to copy original data contents.) </para>
        <screen><![CDATA[$ sudo mv work-dir old-dir
$ sudo mkfs.ext3 /dev/sdx
$ sudo mount -t ext3 /dev/sdx work-dir
$ sudo cp -a old-dir/* work-dir
$ sudo rm -rf old-dir
]]></screen>
        <para/>
      </section>
      <section>
        <title>Expand usable storage space using symlink</title>
        <para>If you have an empty directory (e.g., <code>/path/to/emp-dir</code>) in another partition with usable space, you can create a symlink to the directory with <code>ln</code>(8). </para>
        <screen><![CDATA[$ sudo mv work-dir old-dir
$ sudo mkdir -p /path/to/emp-dir
$ sudo ln -sf /path/to/emp-dir work-dir
$ sudo cp -a old-dir/* work-dir
$ sudo rm -rf old-dir
]]></screen>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> Some software may not function well with "symlink to a directory".   </para>
        <para/>
      </section>
      <section>
        <title>Expand usable storage space using aufs</title>
        <para>If you have usable space in another partition (e.g., <code>/path/to/</code>), you can create a directory in it and stack that on to a directory where you need space with <ulink url="http://en.wikipedia.org/wiki/Aufs">aufs</ulink>. </para>
        <para/>
        <screen><![CDATA[$ sudo mv work-dir old-dir
$ sudo mkdir -p /path/to/emp-dir
$ sudo mount -t aufs -o br:/path/to/emp-dir:old-dir none work-dir
]]></screen>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> Use of <ulink url="http://en.wikipedia.org/wiki/Aufs">aufs</ulink> for long term data storage is not good idea since it is under development and its design change may introduce issues. </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> In order to use <ulink url="http://en.wikipedia.org/wiki/Aufs">aufs</ulink>, its utility package <code>aufs-tools</code> and kernel module package for <ulink url="http://en.wikipedia.org/wiki/Aufs">aufs</ulink> such as <code>aufs-modules-2.6-amd64</code> need to be installed. </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/idea.png" depth="15"/></imageobject><textobject><phrase>(!)</phrase></textobject></inlinemediaobject><ulink url="http://en.wikipedia.org/wiki/Aufs">aufs</ulink> is used to provide writable root filesystem by many modern <ulink url="http://en.wikipedia.org/wiki/Live_CD">live CD</ulink> projects. </para>
        <para/>
      </section>
    </section>
    <section>
      <title>Data encryption tips</title>
      <para>Since gaining root privilege is relatively easy with physical access (see @{@securingtherootpassword@}@), it can not secure your private and sensitive data against possible theft of your PC. You must deploy data encryption technology to do it. Although <ulink url="http://en.wikipedia.org/wiki/GNU_Privacy_Guard">GNU privacy guard</ulink> (see @{@datasecurityinfrastructure@}@) can encrypt files, it takes some user efforts. </para>
      <para><ulink url="http://en.wikipedia.org/wiki/Dm-crypt">dm-crypt</ulink> and <ulink url="http://ecryptfs.sourceforge.net/">eCryptfs</ulink> facilitates automatic data encryption natively via Linux kernel modules with minimal user efforts. </para>
      <table>
        <caption/>
        <tgroup cols="4">
          <colspec colname="xxx1"/>
          <colspec colname="xxx2"/>
          <colspec colname="xxx3"/>
          <colspec colname="xxx4"/>
          <tbody>
            <row>
              <entry>
                <para> List of data encryption utilities. </para>
              </entry>
              <entry>
                <para> 1 </para>
              </entry>
              <entry>
                <para> 2 </para>
              </entry>
              <entry>
                <para> 3 </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <emphasis role="strong">package</emphasis>
                </para>
              </entry>
              <entry>
                <para>
                  <emphasis role="strong">popcon</emphasis>
                </para>
              </entry>
              <entry>
                <para>
                  <emphasis role="strong">size</emphasis>
                </para>
              </entry>
              <entry>
                <para>
                  <emphasis role="strong">function</emphasis>
                </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>cryptsetup</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> Utilities for encrypted block device (<ulink url="http://en.wikipedia.org/wiki/Dm-crypt">dm-crypt</ulink> / <ulink url="http://en.wikipedia.org/wiki/Linux_Unified_Key_Setup">LUKS</ulink>) </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>cryptmount</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> Utilities forencrypted block device (<ulink url="http://en.wikipedia.org/wiki/Dm-crypt">dm-crypt</ulink> / <ulink url="http://en.wikipedia.org/wiki/Linux_Unified_Key_Setup">LUKS</ulink>) with focus on mount/unmount by normal users </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>ecryptfs-utils</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> Utilities for encrypted stacked filesystem (<ulink url="http://ecryptfs.sourceforge.net/">eCryptfs</ulink>) </para>
              </entry>
            </row>
          </tbody>
        </tgroup>
      </table>
      <para><ulink url="http://en.wikipedia.org/wiki/Dm-crypt">Dm-crypt</ulink> is a cryptographic filesystem using <ulink url="http://en.wikipedia.org/wiki/Device_mapper">device-mapper</ulink>. <ulink url="http://en.wikipedia.org/wiki/Device_mapper">Device-mapper</ulink> maps one block device to another. </para>
      <para><ulink url="http://ecryptfs.sourceforge.net/">eCryptfs</ulink> is another cryptographic filesystem using stacked filesystem.  Stacked filesystem stacks itself on top of an existing directory of a mounted filesystem. </para>
      <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/idea.png" depth="15"/></imageobject><textobject><phrase>(!)</phrase></textobject></inlinemediaobject> Entire Debian system can be installed on a encrypted disk by the <ulink url="http://www.debian.org/devel/debian-installer/">debian installer</ulink> (lenny or newer) using <ulink url="http://en.wikipedia.org/wiki/Dm-crypt">dm-crypt</ulink>/<ulink url="http://en.wikipedia.org/wiki/Linux_Unified_Key_Setup">LUKS</ulink> and initramfs.   </para>
      <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> Data encryption costs CPU time etc.  Please weigh its benefits and costs. </para>
      <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> See @{@datasecurityinfrastructure@}@ for user space encryption utility: <ulink url="http://en.wikipedia.org/wiki/GNU_Privacy_Guard">GNU Privacy Guard</ulink>. </para>
      <para/>
      <section>
        <title>Removable disk encryption with dm-crypt/LUKS</title>
        <para>You can encrypt contents of removable mass storage devices, e.g. USB memory stick on <code>/dev/sdx</code>, using <ulink url="http://en.wikipedia.org/wiki/Dm-crypt">dm-crypt</ulink>/<ulink url="http://en.wikipedia.org/wiki/Linux_Unified_Key_Setup">LUKS</ulink>.  You simply formatting it as: </para>
        <screen><![CDATA[# badblocks -c 10240 -s -w -t random -v /dev/sdx
# shred -v -n 1 /dev/sdx
# fdisk /dev/sdx
... "n" "p" "1" "return" "return" "w"
# cryptsetup luksFormat /dev/sdx1
...
# cryptsetup luksOpen /dev/sdx1 sdx1
...
# ls -l /dev/mapper/
total 0
crw-rw---- 1 root root  10, 60 2008-10-04 18:44 control
brw-rw---- 1 root disk 254,  0 2008-10-04 23:55 sdx1
# mkfs.vfat /dev/mapper/sdx1
...
# cryptsetup luksClose sdx1
]]></screen>
        <para>Then, it can be mounted just like normal one on to <code>/media/&lt;disk_label&gt;</code>, except for asking password (see @{@removablemassstoragedevice@}@) under modern desktop environment, such as Gnome using <code>gnome-mount</code>(1).  The difference is that every data written to it is encrypted.  You may alternatively format media in different file format, e.g., ext3 with "<code>mkfs.ext3 /dev/sdx1</code>". </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/idea.png" depth="15"/></imageobject><textobject><phrase>(!)</phrase></textobject></inlinemediaobject> If you are really paranoid for the security of data, you may need to overwrite multiple times in the above example.  This operation is very time consuming though. </para>
        <para/>
      </section>
      <section>
        <title>Encrypted swap partition with dm-crypt</title>
        <para>If your original <code>/etc/fstab</code> contains: </para>
        <screen><![CDATA[/dev/sda7 swap sw 0 0
]]></screen>
        <para>then you can enable encrypted swap partition using <ulink url="http://en.wikipedia.org/wiki/Dm-crypt">dm-crypt</ulink> as </para>
        <screen><![CDATA[# swapoff -a
# echo "cswap /dev/sda7 /dev/urandom swap" >> /etc/crypttab
# perl -i -p -e "s/\/dev\/sda7/\/dev\/mapper\/cswap/" /etc/fstab
# swapon -a
]]></screen>
        <para/>
      </section>
      <section>
        <title>Automatically encrypting files with eCryptfs</title>
        <para>You can encrypt files written under "<code>~/Private/</code>" automatically using <ulink url="http://ecryptfs.sourceforge.net/">eCryptfs</ulink> and the <code>ecryptfs-utils</code> package. </para>
        <itemizedlist>
          <listitem>
            <para>run "<code>ecryptfs-setup-private</code>" and set up "<code>~/Private/</code>" by following prompts. </para>
          </listitem>
          <listitem>
            <para>activate "<code>~/Private/</code>" by issuing "<code>ecryptfs-mount-private</code>". </para>
          </listitem>
          <listitem>
            <para>move sensitive data files to "<code>~/Private/</code>" and make symlinks. </para>
          </listitem>
          <listitem>
            <para>move sensitive data directories to "<code>~/Private/</code>" and make symlinks. </para>
          </listitem>
          <listitem>
            <para>do the same for "<code>~/.gnupg</code>" and other directories containing sensitive data. </para>
          </listitem>
          <listitem>
            <para>create symlink from "<code>~/.ssh</code>" to "<code>~/Private/.ssh</code>" </para>
          </listitem>
          <listitem>
            <para>deactivate "<code>~/Private/</code>" by issuing "<code>ecryptfs-umount-private</code>". </para>
          </listitem>
          <listitem>
            <para>activate "<code>~/Private/</code>" by issuing "<code>ecryptfs-mount-private</code>" as you need encrypted data. </para>
          </listitem>
        </itemizedlist>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> Files and directories with "<code>go-r</code>" permission such as "<code>~/.cvspass</code>", "<code>~/.fetchmailrc</code>", "<code>~/.ssh/identity</code>", "<code>~/.ssh/id_rsa</code>", "<code>~/.ssh/id_dsa</code>", "<code>~/.gnupg/</code>", "<code>~/.gnome2/</code>", ... can be considered sensitive data.   </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> Since <ulink url="http://ecryptfs.sourceforge.net/">eCryptfs</ulink> selectively encrypt only the sensitive files, its system cost is much less than using <ulink url="http://en.wikipedia.org/wiki/Dm-crypt">dm-crypt</ulink> on the entire root or home device.  It does not require any special on-disk storage allocation effort but cannot keep all filesystem metadata confidential. </para>
        <para/>
      </section>
      <section>
        <title>Automatically mounting eCryptfs</title>
        <para>If you use your login password for wrapping encryption keys, you can automate mounting eCryptfs via  Pluggable Authentication Module by having active lines in <code>/etc/pam.d/common-auth</code> as:  </para>
        <screen><![CDATA[auth required pam_unix.so nullok_secure
auth required pam_ecryptfs.so unwrap
]]></screen>
        <para>and active lines in <code>/etc/pam.d/common-session</code> as:  </para>
        <screen><![CDATA[session required pam_unix.so
session optional pam_ecryptfs.so unwrap
]]></screen>
        <para>This is quite convienient. </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> If you use your login password for wrapping encryption keys, your encrypted data are as secure as your user login password (see @{@goodpassword@}@).  Unless you are careful to set up a <ulink url="http://en.wikipedia.org/wiki/Password_strength">strong password</ulink>, your data will be at risk when someone runs <ulink url="http://en.wikipedia.org/wiki/Password_cracking">password cracking</ulink> software after stealing your laptop (see @{@securingtherootpassword@}@).  The <code>squeeze</code> version of the <code>ecryptfs-utils</code> package comes with option to have independent password for wrapping and to set up user's entire home directory for encryption.  This is an actively developed package. </para>
        <para/>
      </section>
    </section>
    <section>
      <title>Monitoring, controlling, and starting program activities</title>
      <para>Program activities can be monitored and controlled using specialized tools. </para>
      <table>
        <caption/>
        <tgroup cols="4">
          <colspec colname="xxx1"/>
          <colspec colname="xxx2"/>
          <colspec colname="xxx3"/>
          <colspec colname="xxx4"/>
          <tbody>
            <row>
              <entry>
                <para> List of tools for monitoring and controlling program activities </para>
              </entry>
              <entry>
                <para> 1 </para>
              </entry>
              <entry>
                <para> 2 </para>
              </entry>
              <entry>
                <para> 3 </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <emphasis role="strong">package</emphasis>
                </para>
              </entry>
              <entry>
                <para>
                  <emphasis role="strong">popcon</emphasis>
                </para>
              </entry>
              <entry>
                <para>
                  <emphasis role="strong">size</emphasis>
                </para>
              </entry>
              <entry>
                <para>
                  <emphasis role="strong">description</emphasis>
                </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>time</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> The <code>time</code>(1) command runs a program to report system resource usages with respect to time. </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>coreutils</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> The <code>nice</code>(1) command runs a program with modified scheduling priority. </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>bsdutils</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> The <code>renice</code>(1) command modifies the scheduling priority of a running process. </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>powertop</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> On Intel-based laptops <code>powertop</code>(1) gives information about system power use. </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>procps</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> The <code>/proc</code> file system utilities: <code>ps</code>(1), <code>top</code>(1), <code>kill</code>(1), <code>watch</code>(1), ... </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>psmisc</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> The <code>/proc</code> file system utilities: <code>killall</code>(1), <code>fuser</code>(1), <code>pstree</code>(1) </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>cron</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> This package run processes according to a schedule (in background). </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>at</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> The <code>at</code>(1) or <code>batch</code>(1) commands run a job at a specified time or below certain load level. </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>lsof</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> The <code>lsof</code>(8) command lists open files by a running process using "<code>-p</code>" option. </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>strace</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> The <code>strace</code>(1) command traces system calls and signals. </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>ltrace</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> The <code>ltrace</code>(1) command traces library calls. </para>
              </entry>
            </row>
            <row>
              <entry>
                <para>
                  <code>xtrace</code>
                </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> - </para>
              </entry>
              <entry>
                <para> The <code>xtrace</code>(1) command traces communication between X11 client and server. </para>
              </entry>
            </row>
          </tbody>
        </tgroup>
      </table>
      <para/>
      <section>
        <title>Time a process</title>
        <para>Display time used by the process invoked by the command. </para>
        <para/>
        <screen><![CDATA[# time some_command >/dev/null
real    0m0.035s       # time on wall clock (elapsed real time)
user    0m0.000s       # time in user mode
sys     0m0.020s       # time in kernel mode
]]></screen>
        <para/>
      </section>
      <section>
        <title>The scheduling priority</title>
        <para>A nice value is used to control the scheduling priority for the process. </para>
        <table>
          <caption/>
          <tgroup cols="2">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <tbody>
              <row>
                <entry>
                  <para> List of nice values for the scheduling priority. </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">nice value</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">scheduling priority</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> 19 </para>
                </entry>
                <entry>
                  <para> lowest priority process (nice) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> 0 </para>
                </entry>
                <entry>
                  <para> very high priority process for user. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> -20 </para>
                </entry>
                <entry>
                  <para> very high priority process for root. (not-nice) </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para/>
        <screen><![CDATA[# nice  -19 top                                      # very nice
# nice --20 wodim -v -eject speed=2 dev=0,0 disk.img # very fast
]]></screen>
        <para>Sometimes an extreme nice value does more harm than good to the system.  Use this command carefully. </para>
        <para/>
      </section>
      <section>
        <title>The ps command</title>
        <para>The <code>ps</code>(1) command on the Debian support both BSD and SystemV features and helps to identify the process activity statically. </para>
        <table>
          <caption/>
          <tgroup cols="3">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <tbody>
              <row>
                <entry>
                  <para> List of ps command styles. </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">style</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">typical command</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">feature</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> BSD </para>
                </entry>
                <entry>
                  <para>
                    <code>ps aux</code>
                  </para>
                </entry>
                <entry>
                  <para> display %CPU %MEM </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> System V </para>
                </entry>
                <entry>
                  <para>
                    <code>ps -efH</code>
                  </para>
                </entry>
                <entry>
                  <para> display PPID </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para>For the zombie (defunct) children process, you can kill them by the parent process ID identified in the (<code>PPID</code>) field. </para>
        <para>The <code>pstree</code>(1) command display a tree of processes. </para>
        <para/>
      </section>
      <section>
        <title>The top command</title>
        <para>The <code>top</code>(1) command on the Debian has rich features and helps to identify what process is acting funny dynamically.   </para>
        <table>
          <caption/>
          <tgroup cols="2">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <tbody>
              <row>
                <entry>
                  <para> List of commands for top. </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">command key</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">response</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para><code>h</code> or <code>?</code> </para>
                </entry>
                <entry>
                  <para> To show help. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>f</code>
                  </para>
                </entry>
                <entry>
                  <para> To set/reset display field. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>o</code>
                  </para>
                </entry>
                <entry>
                  <para> To reorder display field. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>F</code>
                  </para>
                </entry>
                <entry>
                  <para> To set sort key field. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>k</code>
                  </para>
                </entry>
                <entry>
                  <para> To kill a process. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>r</code>
                  </para>
                </entry>
                <entry>
                  <para> To renice a process. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>q</code>
                  </para>
                </entry>
                <entry>
                  <para> To quit the <code>top</code> command. </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para/>
      </section>
      <section>
        <title>List files opened by a process</title>
        <para>You can list all files opened by a process with a process ID (PID), e.g. 1 as: </para>
        <screen><![CDATA[$ sudo lsof -p 1
]]></screen>
        <para>PID=1 is usually <code>init</code> program. </para>
        <para/>
      </section>
      <section>
        <title>Trace program activities</title>
        <para>You can trace program activity with <code>strace</code>(1), <code>ltrace</code>(1), or <code>xtrace</code>(1) commands for system calls and signals, library calls, or communication between X11 client and server.  For example: </para>
        <screen><![CDATA[$ sudo strace ls
...
]]></screen>
        <para/>
      </section>
      <section>
        <title>Identify processes using files or sockets</title>
        <para>You can also identify processes using files or sockets by <code>fuser</code>(1).  For example: </para>
        <screen><![CDATA[$ sudo fuser -v /var/log/mail.log
                     USER        PID ACCESS COMMAND
/var/log/mail.log:   root       2946 F.... syslogd
]]></screen>
        <para>You see that file <code>/var/log/mail.log</code> is open for writing by the <code>syslogd</code>(8) command. </para>
        <para/>
        <screen><![CDATA[$ sudo fuser -v smtp/tcp
                     USER        PID ACCESS COMMAND
smtp/tcp:            Debian-exim   3379 F.... exim4
]]></screen>
        <para>Now you know your system runs <code>exim4</code>(8) to handle <ulink url="http://en.wikipedia.org/wiki/Transmission_Control_Protocol">TCP</ulink> connections to <ulink url="http://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol">SMTP</ulink> port (25). </para>
        <para/>
      </section>
      <section>
        <title>Repeating a command with a constant interval</title>
        <para>The <code>watch</code>(1) command executes a program repeatedly with a constant interval while showing its output in fullscreen. </para>
        <para/>
        <screen><![CDATA[$ watch w
]]></screen>
        <para>This will display who is logged on to the system updated every 2 seconds. </para>
        <para/>
      </section>
      <section>
        <title>Repeating a command looping over files</title>
        <para>There are several ways to repeat a command looping over files matching some condition, e.g. matching glob pattern "<code>*.ext</code>". </para>
        <itemizedlist>
          <listitem>Shell for-loop method (see @{@shellloops@}@): <screen><![CDATA[for x in *.ext; do if [ -f "$x"]; then command "$x" ; fi; done
]]></screen></listitem>
          <listitem>
            <para><code>find</code>(1) and <code>xargs</code>(1) combination: </para>
            <screen><![CDATA[find . -type f -maxdepth 1 -name '*.ext' -print0 | xargs -0 -n 1 command
]]></screen>
          </listitem>
          <listitem>
            <para><code>find</code>(1) with "<code>-exec</code>" option with a command: </para>
            <screen><![CDATA[find . -type f -maxdepth 1 -name '*.ext' -exec command '{}' \;
]]></screen>
          </listitem>
          <listitem>
            <para><code>find</code>(1) with "<code>-exec</code>" option with a short shell script: </para>
            <screen><![CDATA[find . -type f -maxdepth 1 -name '*.ext' -exec sh -c "command '{}' && echo 'successful'" \;
]]></screen>
          </listitem>
        </itemizedlist>
        <para>The above examples are written to ensure proper handling of funny file names such as ones containing spaces.  See @{@idiomsfortheselectionoffiles@}@ for more advance uses of <code>find</code>(1). </para>
        <para/>
      </section>
      <section>
        <title>Starting a program from GUI</title>
        <para>You can set up to start a process from <ulink url="http://en.wikipedia.org/wiki/Graphical_user_interface">graphical user interface (GUI)</ulink>. </para>
        <para>Under Gnome desktop environment, a program program can be started with proper argument by <emphasis role="strong">drag-and-drop</emphasis> of an icon to the launcher icon or by "<emphasis role="strong">Open with ...</emphasis>" menu with right clicking. KDE can do the equivalent, too. Here is an example for Gnome to set up <code>mc</code> program started in <code>gnome-terminal</code>: </para>
        <itemizedlist>
          <listitem>
            <para>create an executable program "<code>mc-term</code>" as: </para>
          </listitem>
        </itemizedlist>
        <para/>
        <screen><![CDATA[# cat >/usr/local/mc-term <<EOF
#!/bin/sh
gnome-terminal -e "mc $1"
EOF
# chmod 755 /usr/local/mc-term
]]></screen>
        <itemizedlist>
          <listitem>create a desktop launcher <itemizedlist><listitem><para>right clicking desktop space to select "<code>Create Launcher ...</code>" </para><itemizedlist><listitem><para>set "Type" to "<code>Application</code>" </para></listitem><listitem><para>set "Name" to "<code>mc</code>" </para></listitem><listitem><para>set "Command" to "<code>mc-term %f</code>" </para></listitem><listitem>click "OK" </listitem></itemizedlist></listitem></itemizedlist></listitem>
          <listitem>create an open-with association <itemizedlist><listitem><para>right click folder to select "<code>Open with Other Application ...</code>" </para><itemizedlist><listitem><para>click open "Use a custom command" dialog and enter "<code>mc-term %f</code>" </para></listitem><listitem>click "Open". </listitem></itemizedlist></listitem></itemizedlist></listitem>
        </itemizedlist>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> Launcher is a file at "<code>~/Desktop</code>" with "<code>desktop</code>" as its extension. </para>
        <para/>
      </section>
      <section>
        <title>Customizing program to be started</title>
        <para>Some programs start another program automatically.  Here are check points for customizing this process: </para>
        <itemizedlist>
          <listitem>
            <para>configuration file of the parent program such as "<code>/etc/mc/mc.ext</code>". </para>
          </listitem>
          <listitem>
            <para>system configuration menu such as "System" -&gt; "Preferences" -&gt; "Preferred Application" for Gnome. </para>
          </listitem>
          <listitem>
            <para>environment variables such as "<code>BROWSER</code>", "<code>EDITOR</code>", "<code>VISUAL</code>", and "<code>PAGER</code>" (see <code>eviron</code>(7)). </para>
          </listitem>
          <listitem>
            <para>the <code>update-alternatives</code>(8) system for programs such as "<code>editor</code>", "<code>view</code>", "<code>x-www-browser</code>", "<code>gnome-www-browser</code>", and "<code>www-browser</code>" (see @{@settingadefaulttexteditor@}@). </para>
          </listitem>
          <listitem>
            <para>the "<code>$HOME/.mailcap</code>" and "<code>/etc/mailcap</code>" file contents which associate <ulink url="http://en.wikipedia.org/wiki/MIME">MIME</ulink> type with program (see <code>mailcap</code>(5)). </para>
          </listitem>
          <listitem>
            <para>the the "<code>$HOME/.mime.types</code>" and "<code>/etc/mime.types</code>" file contents which associate file name extension with <ulink url="http://en.wikipedia.org/wiki/MIME">MIME</ulink> type (see <code>run-mailcap</code>(1)). </para>
          </listitem>
        </itemizedlist>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> The <code>update-mime</code>(8) command updates the "<code>/etc/mailcap</code>" file using "<code>/etc/mailcap.order</code>" file (see <code>mailcap.order</code>(5)). </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> The <code>debianutils</code> package provides <code>sensible-browser</code>(1), <code>sensible-editor</code>(1), and <code>sensible-pager</code>(1) commands which make sensible decisions on which editor, pager, and web browser to call, respectively.  I recommend you to read these shell commands. </para>
        <para/>
      </section>
      <section>
        <title>Kill a process</title>
        <para>Use the <code>kill</code>(1) command to kill (or send a signal to) a process by the process ID. </para>
        <para>Use <code>killall</code>(1) or <code>pkill</code>(1) commands to do the same by the process command name and other attributes. </para>
        <table>
          <caption/>
          <tgroup cols="3">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <tbody>
              <row>
                <entry>
                  <para> List of frequently used signals for kill command. </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">signal value</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">signal name</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">function</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> HUP </para>
                </entry>
                <entry>
                  <para>  restart daemon </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> 15 </para>
                </entry>
                <entry>
                  <para> TERM </para>
                </entry>
                <entry>
                  <para> normal kill </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> 9 </para>
                </entry>
                <entry>
                  <para> KILL </para>
                </entry>
                <entry>
                  <para> kill hard </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para/>
      </section>
      <section>
        <title>Schedule tasks once</title>
        <para>Run the <code>at</code>(1) command to schedule a one-time job: </para>
        <screen><![CDATA[$ echo 'command -args'| at 3:40 monday
]]></screen>
        <para/>
      </section>
      <section>
        <title>Schedule tasks regularly</title>
        <para>Use <code>cron</code>(8) to schedule tasks regularly.  See <code>crontab</code>(1) and <code>crontab</code>(5). </para>
        <para>Run the command "<code>crontab -e</code>" to create or edit a crontab file to set up regularly scheduled events.   </para>
        <para>Example of a crontab file: </para>
        <screen><![CDATA[# use /bin/sh to run commands, no matter what /etc/passwd says
SHELL=/bin/sh
# mail any output to paul, no matter whose crontab this is
MAILTO=paul
# Min Hour DayOfMonth Month DayOfWeek command (Day... are OR'ed)
# run at 00:05, every day
5  0  *  * *   $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
# run at 14:15 on the first of every month -- output mailed to paul
15 14 1  * *   $HOME/bin/monthly
# run at 22:00 on weekdays(1-5), annoy Joe. % for newline, last % for cc:
0 22 *   * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?%.%%
23 */2 1 2 *   echo "run 23 minutes after 0am, 2am, 4am ..., on Feb 1"
5  4 *   * sun echo "run at 04:05 every sunday"
# run at 03:40 on the first Monday of each month
40 3 1-7 * *   [ "$(date +%a)" == "Mon" ] && command -args
]]></screen>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> For the system not running continuously, install the <code>anacron</code> package to schedule periodic command at the specified intervals as closely as machine-uptime permits. </para>
        <para/>
      </section>
      <section>
        <title>Alt-SysRq</title>
        <para>Insurance against system malfunction is provided by the kernel compile option "Magic <ulink url="/SysRq">SysRq</ulink> key" (SAK key) which is now the default for the Debian kernel.  Pressing Alt-<ulink url="/SysRq">SysRq</ulink> followed by one of the following keys does the magic of rescuing control of the system: </para>
        <table>
          <caption/>
          <tgroup cols="2">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <tbody>
              <row>
                <entry>
                  <para> List of SAK command keys. </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">key following Alt-<ulink url="/SysRq">SysRq</ulink></emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">function</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>r</code>
                  </para>
                </entry>
                <entry>
                  <para> Un<emphasis role="strong">r</emphasis>aw restores the keyboard after things like X crashes. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>0</code>
                  </para>
                </entry>
                <entry>
                  <para> Changing the console loglevel to <emphasis role="strong">0</emphasis> reduces error messages. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>k</code>
                  </para>
                </entry>
                <entry>
                  <para> SAK (system attention key) <emphasis role="strong">k</emphasis>ills all processes on the <emphasis role="strong">current virtual console</emphasis>. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>e</code>
                  </para>
                </entry>
                <entry>
                  <para> Send a SIGT<emphasis role="strong">E</emphasis>RM to all processes, except for <code>init</code>. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>i</code>
                  </para>
                </entry>
                <entry>
                  <para> Send a SIGK<emphasis role="strong">I</emphasis>LL to all processes, except for <code>init</code>. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>s</code>
                  </para>
                </entry>
                <entry>
                  <para><emphasis role="strong">S</emphasis>ync all mounted filesystems. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>u</code>
                  </para>
                </entry>
                <entry>
                  <para> Remount all mounted filesystems read-only (<emphasis role="strong">u</emphasis>mount). </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>b</code>
                  </para>
                </entry>
                <entry>
                  <para> Re<emphasis role="strong">b</emphasis>oot the system without syncing or unmounting. </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para>The combination of "Alt-<ulink url="/SysRq">SysRq</ulink> s", "Alt-<ulink url="/SysRq">SysRq</ulink> u", and "Alt-<ulink url="/SysRq">SysRq</ulink> r" is good for getting out of really bad situations. </para>
        <para>See <code>/usr/share/doc/linux-doc-2.6.*/Documentation/sysrq.txt.gz</code> . </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> The Alt-<ulink url="/SysRq">SysRq</ulink> feature may be considered a security risk by allowing users access to root-privileged functions.  Placing "<code>echo 0 &gt;/proc/sys/kernel/sysrq</code>" in <code>/etc/rc.local</code> or "<code>kernel.sysrq = 0</code>" in <code>/etc/sysctl.conf</code> will disable the Alt-<ulink url="/SysRq">SysRq</ulink> feature. </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> From SSH terminal etc., you can use the Alt-<ulink url="/SysRq">SysRq</ulink> feature by writing to the <code>/proc/sysrq-trigger</code>. For example, "<code>echo s &gt; /proc/sysrq-trigger; echo u &gt; /proc/sysrq-trigger</code>" from the root shell prompt will <emphasis role="strong">s</emphasis>ync and <emphasis role="strong">u</emphasis>mount all mounted filesystems. </para>
        <para/>
      </section>
    </section>
    <section>
      <title>System maintenance tips</title>
      <para/>
      <section>
        <title>Who is logged on</title>
        <para>You can check who is logged on to the system with <code>w</code>(1) or <code>who</code>(1) commands. </para>
        <para/>
      </section>
      <section>
        <title>Warn everyone</title>
        <para>You can send message to everyone who is logged on to the system with the <code>wall</code>(1) command: </para>
        <screen><![CDATA[$ echo "We are shutting down in 1 hour" | wall
]]></screen>
        <para/>
      </section>
      <section>
        <title>The hardware identification</title>
        <para>For the <ulink url="http://en.wikipedia.org/wiki/Peripheral_Component_Interconnect">PCI</ulink>-like devices (<ulink url="http://en.wikipedia.org/wiki/Accelerated_Graphics_Port">AGP</ulink>, <ulink url="http://en.wikipedia.org/wiki/PCI_Express">PCI-Express</ulink>, <ulink url="http://en.wikipedia.org/wiki/PC_Card#CardBus">CardBus</ulink>, <ulink url="http://en.wikipedia.org/wiki/ExpressCard">ExpressCard</ulink>, etc.), <code>lspci</code>(8) command (probably with "<code>-nn</code>" option) is a good start for the hardware identification </para>
        <para>Alternatively, you can identify the hardware by reading contents of <code>/proc/bus/pci/devices</code> or browsing directory tree under <code>/sys/bus/pci</code> (see @{@procfsandsysfs@}@). </para>
        <table>
          <caption/>
          <tgroup cols="4">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <tbody>
              <row>
                <entry>
                  <para> List of hardware identification tools. </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">popcon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">description</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>pciutils</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Linux PCI Utilities, <code>lspci</code>(8) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>usbutils</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Linux USB utilities, <code>lsusb</code>(8) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>pcmciautils</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> PCMCIA utilities for Linux 2.6, <code>pccardctl</code>(8) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>scsitools</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Collection of tools for SCSI hardware management, <code>lsscsi</code>(8) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>pnputils</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Plug and Play BIOS utilities, <code>lspnp</code>(8) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>procinfo</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Displays system information from <code>/proc</code>, <code>lsdev</code>(8) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>lshw</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Information about hardware configuration, <code>lshw</code>(1) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>discover</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Hardware identification system, <code>discover</code>(8) </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para/>
      </section>
      <section>
        <title>The hardware configuration</title>
        <para>Although most of the hardware configuration on modern GUI desktop systems such as Gnome and KDE can be managed through accompanying GUI configuration tools, it is a good idea to know some basics methods to configure them. </para>
        <table>
          <caption/>
          <tgroup cols="4">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <tbody>
              <row>
                <entry>
                  <para> List of hardware configuration tools. </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">popcon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">description</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>hal</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Hardware Abstraction Layer, <code>lshal</code>(1) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>console-tools</code>
                  </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Linux console font and keytable utilities. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>x11-xserver-utils</code>
                  </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> X server utilities. <code>xset</code>(1) and <code>xmodmap</code>(1) commands. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>acpid</code>
                  </para>
                </entry>
                <entry>
                  <para> 24513 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Daemon to manage events delivered by the Advanced Configuration and Power Interface (ACPI) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>acpi</code>
                  </para>
                </entry>
                <entry>
                  <para> 2563 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for ACPI devices </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>apmd</code>
                  </para>
                </entry>
                <entry>
                  <para> 1222  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Daemon to manage events delivered by the Advanced Power Management (APM) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>powersaved</code>
                  </para>
                </entry>
                <entry>
                  <para> 1038 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Daemon to manage battery, temperature, ac, cpufreq (<ulink url="/SpeedStep">SpeedStep</ulink>, Powernow!) control and monitor with ACPI and APM supports. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>noflushd</code>
                  </para>
                </entry>
                <entry>
                  <para> 95 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Allow idle hard disks to spin down </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>sleepd</code>
                  </para>
                </entry>
                <entry>
                  <para> 75 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Puts a laptop to sleep during inactivity </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>hdparm</code>
                  </para>
                </entry>
                <entry>
                  <para> 5192 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Hard disk access optimization.  Very effective but dangerous.  You must read <code>hdparm</code>(8) first. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>smartmontools</code>
                  </para>
                </entry>
                <entry>
                  <para> 3526 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Control and monitor storage systems using S.M.A.R.T. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>setserial</code>
                  </para>
                </entry>
                <entry>
                  <para> 2619 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Collection of tools for serial port management. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>memtest86+</code>
                  </para>
                </entry>
                <entry>
                  <para> 406 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Collection of tools for memory hardware management. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>scsitools</code>
                  </para>
                </entry>
                <entry>
                  <para> 185 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Collection of tools for SCSI hardware management. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>tpconfig</code>
                  </para>
                </entry>
                <entry>
                  <para> 276 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> A program to configure touchpad devices </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>setcd</code>
                  </para>
                </entry>
                <entry>
                  <para> 82 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Compact disc drive access optimization. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>big-cursor</code>
                  </para>
                </entry>
                <entry>
                  <para> *121 </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Larger mouse cursors for X </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>lspowertweak</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Simple front end to powertweak, <code>lspowertweak</code>(8) </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para>Here, ACPI is a newer framework for the power management system than APM. </para>
        <para/>
      </section>
      <section>
        <title>System and hardware time</title>
        <para>The following will set system and hardware time to MM/DD hh:mm, CCYY.   </para>
        <screen><![CDATA[# date MMDDhhmmCCYY
# hwclock --utc --systohc
# hwclock --show
]]></screen>
        <para>Times are normally displayed in the local time on the Debian system but the hardware and system time usually use UTC. </para>
        <para>If the hardware (BIOS) time is set to GMT, change the setting to <code>UTC=yes</code> in the <code>/etc/default/rcS</code>. </para>
        <para>If you wish to update system time via network, consider to use the NTP service with the packages such as <code>ntp</code>, <code>ntpdate</code>, and <code>chrony</code>. See: </para>
        <itemizedlist>
          <listitem>
            <para><ulink url="http://www.tldp.org/HOWTO/TimePrecision-HOWTO/index.html">Managing Accurate Date and Time HOWTO</ulink> . </para>
          </listitem>
          <listitem>
            <para><ulink url="http://www.ntp.org/">NTP Public Services Project</ulink> . </para>
          </listitem>
          <listitem>
            <para>The <code>ntp-doc</code> package </para>
          </listitem>
        </itemizedlist>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> The <code>ntptrace</code>(8) command in the <code>ntp</code> package can trace a chain of NTP servers back to the primary source. </para>
        <para/>
      </section>
      <section>
        <title>The terminal configuration</title>
        <para>There are several components to configure character console and <code>ncurses</code>(3) system features: </para>
        <itemizedlist>
          <listitem>
            <para>the <code>terminfo</code>(5) file </para>
          </listitem>
          <listitem>
            <para>the <code>TERM</code>(7) environment variable </para>
          </listitem>
          <listitem>
            <para>the <code>setterm</code>(1) command </para>
          </listitem>
          <listitem>
            <para>the <code>stty</code>(1) command </para>
          </listitem>
          <listitem>
            <para>the <code>tic</code>(1) command </para>
          </listitem>
          <listitem>
            <para>the <code>toe</code>(1) command </para>
          </listitem>
        </itemizedlist>
        <para>If the <code>terminfo</code> entry for <code>xterm</code> doesn't work with a non-Debian <code>xterm</code>, change your terminal type from <emphasis role="strong"><code>xterm</code></emphasis> to one of the feature-limited versions such as <emphasis role="strong"><code>xterm-r6</code></emphasis> when you log in to a Debian system remotely.  See <code>/usr/share/doc/libncurses5/FAQ</code> for more.  <emphasis role="strong"><code>dumb</code></emphasis> is the lowest common denominator for <code>terminfo</code>. </para>
        <para/>
      </section>
      <section>
        <title>The sound infrastructure</title>
        <para>Device drivers for sound cards for current Linux 2.6 are provided by <ulink url="http://en.wikipedia.org/wiki/Advanced_Linux_Sound_Architecture">Advanced Linux Sound Architecture (ALSA)</ulink>.  ALSA provides emulation mode for previous <ulink url="http://en.wikipedia.org/wiki/Open_Sound_System">Open Sound System (OSS)</ulink> for compatibility.   </para>
        <para>Run "<code>dpkg-reconfigure linux-sound-base</code>" to select the sound system to use ALSA via blacklisting of kernel modules. Unless you have very new sound hardware, udev infrastructure should configure your sound system. </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> Use "<code>cat /dev/urandom &gt; /dev/audio</code>" or the <code>speaker-test</code>(1) command to test speaker. (^C to stop) </para>
        <para><inlinemediaobject><imageobject><imagedata width="16" fileref="/htdocs/rightsidebar/img/icon-info.png" depth="16"/></imageobject><textobject><phrase>{i}</phrase></textobject></inlinemediaobject> If you can not get sound, your speaker may be connected to a muted output.  Modern sound system has many outputs.  The <code>alsamixer</code>(1) command in the <code>alsa-utils</code> package is useful to configure volume and mute settings. </para>
        <para>Application softwares may be configured not only to access sound devices directly but also to access them via some standardized sound server system. </para>
        <para/>
        <table>
          <caption/>
          <tgroup cols="4">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <tbody>
              <row>
                <entry>
                  <para> List of sound packages </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">pocon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">description</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>linux-sound-base</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Base package for ALSA and OSS sound systems </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>alsa-base</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> ALSA driver configuration files </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>alsa-utils</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Utilities for configuring and using ALSA </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>oss-compat</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> OSS compatibility under ALSA preventing "<code>/dev/dsp not found</code>" errors </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>esound-common</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Enlightened_Sound_Daemon">Enlightened Sound Daemon (ESD)</ulink> common (Enlightenment and GNOME) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>esound</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Enlightened_Sound_Daemon">Enlightened Sound Daemon (ESD)</ulink> server (Enlightenment and GNOME) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>esound-clients</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Enlightened_Sound_Daemon">Enlightened Sound Daemon (ESD)</ulink> client (Enlightenment and GNOME) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libesd-alsa0</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Enlightened_Sound_Daemon">Enlightened Sound Daemon (ESD)</ulink> library Enlightenment and GNOME) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libesd0</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Enlightened_Sound_Daemon">Enlightened Sound Daemon (ESD)</ulink> library (Enlightenment and GNOME) - OSS </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>arts</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/ARts">aRts</ulink> server (KDE) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libarts1c2a</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/ARts">aRts</ulink> library (KDE) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libartsc0</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/ARts">aRts</ulink> library (KDE) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>jackd</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/JACK_Audio_Connection_Kit">JACK Audio Connection Kit. (JACK)</ulink> server (low latency) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libjack0</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/JACK_Audio_Connection_Kit">JACK Audio Connection Kit. (JACK)</ulink> library (low latency) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libjack0.100.0-0</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/JACK_Audio_Connection_Kit">JACK Audio Connection Kit. (JACK)</ulink> library (low latency) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>nas</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Network_Audio_System">Network Audio System (NAS)</ulink> server </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libaudio2</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Network_Audio_System">Network Audio System (NAS)</ulink>  library </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>pulseaudio</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/PulseAudio">PulseAudio</ulink> server, replacement for ESD </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libpulse0</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/PulseAudio">PulseAudio</ulink> client library, replacement for ESD </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libpulsecore5</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/PulseAudio">PulseAudio</ulink> server library, replacement for ESD </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libgstreamer0.10-0</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/GStreamer">GStreamer</ulink>: Gnome sound engine </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libxine1</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Xine">xine</ulink>: KDE older sound engine </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libphonon4</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Phonon_(KDE)">Phonon</ulink>: KDE new sound engine </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para>There is usually a common sound engine for each popular desktop environment. Each sound engine used by the application can choose to connect to different sound servers. </para>
        <para/>
      </section>
      <section>
        <title>Disable the screen saver</title>
        <para>For disabling the screen saver, use following commands. </para>
        <table>
          <caption/>
          <tgroup cols="2">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <tbody>
              <row>
                <entry>
                  <para> List of commands for disabling the screen saver. </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">environment</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">command</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> The Linux console </para>
                </entry>
                <entry>
                  <para>
                    <code>setterm -powersave off</code>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> The X Window by turning off screensaver </para>
                </entry>
                <entry>
                  <para>
                    <code>xset s off</code>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> The X Window by disabling dpms </para>
                </entry>
                <entry>
                  <para>
                    <code>xset -dpms</code>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> The X Window by GUI configuration of screen saver </para>
                </entry>
                <entry>
                  <para>
                    <code>xscreensaver-command -prefs</code>
                  </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para/>
      </section>
      <section>
        <title>Disable the sound (beep)</title>
        <para>One can always unplug the PC speaker.  <inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/smile4.png" depth="15"/></imageobject><textobject><phrase>;-)</phrase></textobject></inlinemediaobject>  Removing <code>pcspkr</code> kernel module does this for you. </para>
        <para>The following will prevent the <code>readline</code> program used by the <code>bash</code> to beep when encountering "\a" (ASCII=7): </para>
        <screen><![CDATA[$ echo "set bell-style none">> ~/.inputrc
]]></screen>
        <para/>
      </section>
      <section>
        <title>Memory usage</title>
        <para>The kernel boot message in the <code>/var/log/dmesg</code> contains the total exact size of available memory.  </para>
        <para>The <code>free</code>(1) and <code>top</code>(1) commands display information on memory resources on the running system. </para>
        <para/>
        <screen><![CDATA[$ grep '^Memory' /var/log/dmesg
Memory: 990528k/1016784k available (1975k kernel code, 25868k reserved, 931k data, 296k init)
$ free -k
             total       used       free     shared    buffers     cached
Mem:        997184     976928      20256          0     129592     171932
-/+ buffers/cache:     675404     321780
Swap:      4545576          4    4545572
]]></screen>
        <para>For my <ulink url="/MacBook">MacBook</ulink> with 1GB=1048576k DRAM (video system steals some of this):  </para>
        <table>
          <caption/>
          <tgroup cols="2">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <tbody>
              <row>
                <entry>
                  <para> List of memory sizes reported. </para>
                </entry>
                <entry>
                  <para> </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">report</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> Total size in dmesg </para>
                </entry>
                <entry>
                  <para> 1016784k = 1GB - 31792k </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> Free in dmesg </para>
                </entry>
                <entry>
                  <para> 990528k </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> Total under shell </para>
                </entry>
                <entry>
                  <para> 997184k </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para> Free under shell </para>
                </entry>
                <entry>
                  <para> 20256k </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para>Do not worry about the large size of "<code>used</code>" and the small size of "<code>free</code>" in the "<code>Mem:</code>" line, but read the one under them (675404 and 321780 in the example below) and relax. </para>
        <para/>
      </section>
      <section>
        <title>System security and integrity check</title>
        <para>Poor system maintenance may expose your system to external exploitation.   </para>
        <para>For system security and integrity check, you should start with: </para>
        <itemizedlist>
          <listitem>
            <para><code>debsums</code> package: See <code>debsums</code>(1) and @{@toplevelreleasefileandauthenticity@}@. </para>
          </listitem>
          <listitem>
            <para><code>chkrootkit</code> package: See <code>chkrootkit</code>(1). </para>
          </listitem>
          <listitem>
            <para><code>clamav</code> package family: See <code>clamscan</code>(1) and <code>freahclam</code>(1). </para>
          </listitem>
          <listitem>
            <para><ulink url="http://www.debian.org/security/faq">Debian security FAQ</ulink>. </para>
          </listitem>
          <listitem>
            <para><ulink url="http://www.debian.org/doc/manuals/securing-debian-howto/">Securing Debian Manual</ulink>. </para>
          </listitem>
        </itemizedlist>
        <table>
          <caption/>
          <tgroup cols="4">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <tbody>
              <row>
                <entry>
                  <para> List of tools for system security and integrity check </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">popcon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">description</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>logcheck</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> This mails anomalies in the system logfiles to the administrator </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>debsums</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> This verifies installed package files against MD5 checksums. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>chkrootkit</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Rootkit">Rootkit</ulink> detector. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>clamav</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Anti-virus utility for Unix - command-line interface. </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>tiger</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Report system security vulnerabilities </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>tripwire</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> File and directory integrity checker </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>john</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Active password cracking tool  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>aide</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Advanced Intrusion Detection Environment - static binary </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>bastille</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Security hardening tool </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>integrit</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> A file integrity verification program </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>crack</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Password guessing program </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para>Here is a simple script to check for typical world writable incorrect file permissions. </para>
        <screen><![CDATA[# find / -perm 777 -a \! -type s -a \! -type l -a \! \( -type d -a -perm 1777 \)
]]></screen>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> Since the <code>debsums</code> package uses MD5 checksums stored locally, it can not be fully trusted as the system security audit tool against malicious attacks. </para>
        <para/>
      </section>
    </section>
    <section>
      <title>The kernel</title>
      <para>Debian distributes modularized Linux kernel as packages for supported architectures.   </para>
      <para/>
      <section>
        <title>Linux kernel 2.6</title>
        <para>There are few notable features on Linux kernel 2.6 compared to 2.4. </para>
        <itemizedlist>
          <listitem>Devices are created by the udev system (see @{@theudevsystem@}@). </listitem>
          <listitem>
            <para>Read/write accesses to IDE CD/DVD devices do not use the <code>ide-scsi</code> module. </para>
          </listitem>
          <listitem>
            <para>Network packet filtering functions use <code>iptable</code> kernel modules. </para>
          </listitem>
        </itemizedlist>
        <para/>
      </section>
      <section>
        <title>Kernel headers</title>
        <para>Most <emphasis role="strong">normal programs</emphasis> don't need kernel headers and in fact may break if you use them directly for compiling. They should be compiled against the headers in <code>/usr/include/linux</code> and <code>/usr/include/asm</code> provided by the <code>libc6-dev</code> package (created from the <code>glibc</code> source package) on the Debian system. </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/idea.png" depth="15"/></imageobject><textobject><phrase>(!)</phrase></textobject></inlinemediaobject> For compiling some kernel-specific programs such as the kernel modules from the external source and the automounter daemon (<code>amd</code>), you must include path to the corresponding kernel headers, e.g. <code>-I/usr/src/linux-particular-version/include/</code> , to your command line.  The <code>module-assistant</code> package helps users to build and install module package(s) easily for one or more custom kernels with the <code>m-a</code>(8) command. </para>
        <para/>
      </section>
      <section>
        <title>Kernel and module compile</title>
        <para>Debian has its own method of compiling the kernel and related modules. </para>
        <table>
          <caption/>
          <tgroup cols="4">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <tbody>
              <row>
                <entry>
                  <para> List of key packages to be installed for the kernel recompilation on the Debian system </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">popcon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">description</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>build-essential</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> essential packages for building Debian packages: <code>make</code>, <code>gcc</code>, ... </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>bzip2</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> compress and decompress utilities for bz2 files </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>libncurses5-dev</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> developer's libraries and docs for ncurses </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>git-core</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> git: distributed revision control system used by the Linux kernel </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>fakeroot</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> provide fakeroot environment for building package as non-root </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>initramfs-tools</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> tool to build an initramfs (Debian specific) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>kernel-package</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> tool to build Linux kernel packages (Debian specific) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>module-assistant</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> tool to help build module packages (Debian specific) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>devscripts</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> helper scripts for a Debian Package maintainer (Debian specific) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>linux-tree-2.6.*</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Linux kernel source tree for building Debian kernel images (Debian specific) </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para>If you use <code>initrd</code> in @{@stagecthebootloader@}@, make sure to read the related information in <code>initramfs-tools</code>(8), <code>update-initramfs</code>(8), <code>mkinitramfs</code>(8) and <code>initramfs.conf</code>(5).  </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/alert.png" depth="15"/></imageobject><textobject><phrase>/!\</phrase></textobject></inlinemediaobject> Do not put symlinks to the directories in the source tree (e.g. <code>/usr/src/linux*</code>) from <code>/usr/include/linux</code> and <code>/usr/include/asm</code> when compiling the Linux kernel source. (Some outdated documents suggest this.) </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/idea.png" depth="15"/></imageobject><textobject><phrase>(!)</phrase></textobject></inlinemediaobject> When compiling the latest Linux kernel on the Debian <code>stable</code> system, the use of backported latest tools from the Debian <code>unstable</code> may be needed. </para>
        <para/>
      </section>
      <section>
        <title>Kernel source compile: Debian standard method</title>
        <para>The Debian standard method for compiling kernel source to create a custom kernel package uses <code>make-kpkg</code>(1) command. The official documentation is in (the bottom of) <code>/usr/share/doc/kernel-package/README.gz</code>.  See <code>kernel-pkg.conf</code>(5) and <code>kernel-img.conf</code>(5) for customization. </para>
        <para>Here is an example for amd64 system: </para>
        <screen><![CDATA[# aptitude install linux-tree-<version>
$ cd /usr/src
$ tar -xjvf linux-source-<version>.tar.bz2
$ cd linux-source-<version>
$ cp /boot/config-<oldversion> .config
$ make menuconfig
 ...
$ make-kpkg clean
$ fakeroot make-kpkg --append_to_version -amd64 --initrd --revision=rev.01 kernel_image modules_image
$ cd ..
# dpkg -i linux-image*.deb
]]></screen>
        <itemizedlist>
          <listitem>
            <para>reboot to new kernel with "<code>shutdown -r now</code>" . </para>
          </listitem>
        </itemizedlist>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> When you intend to create a non-modularized kernel compiled only for one machine, invoke <code>make-kpkg</code> command without "<code>--initrd</code>" option since initrd is not used. Invocation of "<code>make oldconfig</code>" and "<code>make dep</code>" are not required since "<code>make-kpkg kernel_image</code>" invokes them. </para>
        <para/>
      </section>
      <section>
        <title>Module source compile: Debian standard method</title>
        <para>The Debian standard method for creating and installing a custom module package for a custom kernel package uses <code>module-assistant</code>(8) command and module-source packages. For example, following will build the <code>unionfs</code> kernel module package and installs it. </para>
        <screen><![CDATA[$ sudo aptitude install module-assistant
...
$ sudo aptitude install unionfs-source unionfs-tools unionfs-utils
$ sudo m-a update
$ sudo m-a prepare
$ sudo m-a auto-install unionfs
...
$ sudo apt-get autoremove
]]></screen>
        <para/>
      </section>
      <section>
        <title>Kernel source compile: classic method</title>
        <para>You can still build <ulink url="http://www.kernel.org/">Linux kernel from the pristine sources</ulink> with the classic method.  You must take care the details of the system configuration manually. </para>
        <screen><![CDATA[$ cd /usr/src
$ wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-<version>.tar.bz2
$ tar -xjvf linux-<version>.tar.bz2
$ cd linux-<version>
$ cp /boot/config-<version> .config
$ make menuconfig
 ...
$ make dep; make bzImage
$ make modules
# cp ./arch/x86_64/boot/bzImage /boot/vmlinuz-<version>
# make modules_install
# depmod -a
# update-initramfs -c -k <version>
]]></screen>
        <itemizedlist>
          <listitem>set up bootloader <itemizedlist><listitem><para>edit <code>/etc/lilo.conf</code> and run <code>/sbin/lilo</code>, if you use <code>lilo</code> . </para></listitem><listitem><para>edit <code>/boot/grub/menu.lst</code>, if you use <code>grub</code> . </para></listitem></itemizedlist></listitem>
          <listitem>
            <para>reboot to new kernel with "<code>shutdown -r now</code>" . </para>
          </listitem>
        </itemizedlist>
        <para/>
      </section>
      <section>
        <title>Non-free hardware drivers</title>
        <para>Although most of hardware drivers are available as free software and as a part of the Debian system, you may need to load some non-free external drivers to support some hardwares, such as Winmodem, on your system. </para>
        <para>Check pertinent resources: </para>
        <itemizedlist>
          <listitem>
            <para>
              <ulink url="http://en.wikipedia.org/wiki/Softmodem">http://en.wikipedia.org/wiki/Softmodem</ulink>
            </para>
          </listitem>
          <listitem>
            <para>
              <ulink url="http://en.wikipedia.org/wiki/Comparison_of_open_source_wireless_drivers">http://en.wikipedia.org/wiki/Comparison_of_open_source_wireless_drivers</ulink>
            </para>
          </listitem>
          <listitem>
            <para><ulink url="http://www.google.com">Google</ulink> or other search engines with keyword "Linmodem". </para>
          </listitem>
          <listitem>
            <para>
              <ulink url="http://ndiswrapper.sourceforge.net">http://ndiswrapper.sourceforge.net</ulink>
            </para>
          </listitem>
          <listitem>
            <para>
              <ulink url="http://linuxwireless.org">http://linuxwireless.org</ulink>
            </para>
          </listitem>
          <listitem>
            <para><ulink url="http://madwifi-project.org">http://madwifi-project.org</ulink> (there is ath5k which contains free drivers) </para>
          </listitem>
        </itemizedlist>
        <para/>
      </section>
    </section>
    <section>
      <title>The chroot</title>
      <para>The <code>chroot</code>(8) program is most basic way to run different instances of the GNU/Linux environment on a single system simultaneously without rebooting. I will explain simple <ulink url="http://en.wikipedia.org/wiki/Chroot">chroot</ulink> systems in the following as examples. </para>
      <para>For serious chroot setup with the detail configuration, please consider to use the specialized <code>schroot</code> package. </para>
      <para/>
      <section>
        <title>Run a different Debian distribution with chroot</title>
        <para>A chroot Debian environment can easily be created by the <code>debootstrap</code> or <code>cdebootstrap</code> command. </para>
        <para>For example, the following will create a <code>sid</code> chroot on <code>/sid-root</code> while having fast Internet access: </para>
        <para/>
        <screen><![CDATA[main # debootstrap sid /sid-root http://ftp.debian.org/debian/
]]></screen>
        <itemizedlist>
          <listitem>watch it download the whole system </listitem>
        </itemizedlist>
        <para/>
        <screen><![CDATA[main # echo "proc-sid    /sid-root/proc     proc   none 0 0" >> /etc/fstab
main # echo "devpts-sid  /sid-root/dev/pts  devpts defaults 0 0" >> /etc/fstab
main # mount -a
main # cp -f /etc/passwd /sid-root/etc/passwd
main # cp -f /etc/shadow /sid-root/etc/shadow
main # cp -f /etc/group  /sid-root/etc/group
main # cp -f /etc/hosts  /sid-root/etc/hosts
main # chroot /sid-root /bin/bash
chroot # cd /dev; /sbin/MAKEDEV generic ; cd -
chroot # vi /etc/apt/sources.list
]]></screen>
        <itemizedlist>
          <listitem>point the source to unstable </listitem>
        </itemizedlist>
        <para/>
        <screen><![CDATA[chroot # aptitude update
...
chroot # aptitude install locales
...
]]></screen>
        <itemizedlist>
          <listitem>add "en_US.UTF-8" as locale and make it default </listitem>
        </itemizedlist>
        <para/>
        <screen><![CDATA[Do you want to continue? [Y/n/?] y
chroot # aptitude install mc vim
...
Do you want to continue? [Y/n/?] y
...
chroot # exit
main #
]]></screen>
        <para>At this point you should have a fully working Debian sid system, where you can play around without fear of affecting your main Debian installation. </para>
        <para><inlinemediaobject><imageobject><imagedata width="15" fileref="/htdocs/rightsidebar/img/attention.png" depth="15"/></imageobject><textobject><phrase>&lt;!&gt;</phrase></textobject></inlinemediaobject> If you use bind mount for directories such as home directory in the chroot, you must be careful for its side effects.  I heard people lost their home directory after executing "<code>rm -rf /sid-root</code>" <emphasis role="strong">without unbinding</emphasis> their home directory in the chroot. A <emphasis role="strong">bind mount</emphasis> is not normally visible with "<code>df</code>", you need to execute "<code>df -a</code>" to see it.   </para>
        <para>This <code>debootstrap</code> trick can also be used to <ulink url="http://www.debian.org/releases/stable/installmanual">install Debian</ulink> to a system without using a Debian install disk, but instead from another GNU/Linux distribution. </para>
        <para/>
      </section>
      <section>
        <title>Setting up login for chroot</title>
        <para>Typing "<code>chroot /sid-root /bin/bash</code>" is easy, but it retains all sorts of environment variables that you may not want, and has other issues.  A much better approach is to run another login process on a separate virtual terminal where you can log in to the chroot directly. </para>
        <para>Since on default Debian systems <code>tty1</code> to <code>tty6</code> run Linux consoles and <code>tty7</code> runs the X Window System, let's set up <code>tty8</code> for a chrooted console as an example.  After creating a chroot system, type from the root shell of the main system: </para>
        <para/>
        <screen><![CDATA[main # echo "8:23:respawn:/usr/sbin/chroot /sid-root /sbin/getty 38400 tty8"  >> /etc/inittab
main # init q
]]></screen>
        <itemizedlist>
          <listitem>reload init </listitem>
        </itemizedlist>
        <para/>
      </section>
      <section>
        <title>Setting up X for chroot</title>
        <para>You want to run the latest X and GNOME safely in your chroot?  That's entirely possible!  The following example will make GDM run on virtual terminal <code>vt9</code>. </para>
        <para>First install a chroot system.  From the root of the main system, copy key configuration files to the chroot system. </para>
        <screen><![CDATA[main # cp /etc/X11/xorg.conf /sid-root/etc/X11/xorg.conf
main # chroot /sid-root
chroot # cd /dev; /sbin/MAKEDEV generic ; cd -
chroot # aptitude install gdm gnome x-window-system
chroot # vim /etc/gdm/gdm.conf
]]></screen>
        <itemizedlist>
          <listitem>
            <para>change "<code>[servers]</code>" section with "<code>s/vt7/vt9/</code>" to make the first virtual console in the chroot from <code>vt7</code> to <code>vt9</code>. </para>
          </listitem>
        </itemizedlist>
        <para/>
        <screen><![CDATA[chroot # /etc/init.d/gdm start
]]></screen>
        <para>Now you can easily switch back and forth between full X environments in your chroot and your main system just by switching between Linux virtual terminals; e.g.  by using Ctrl-Alt-F7 and Ctrl-Alt-F9.  Have fun! </para>
        <para/>
      </section>
      <section>
        <title>Run other distributions with chroot</title>
        <para>A chroot environment for another Linux distribution can easily be created. You install a system into separate partitions using the installer of the other distribution.  If its root partition is in <code>/dev/hda9</code>: </para>
        <screen><![CDATA[main # cd / ; mkdir /other-dist
main # mount -t ext3 /dev/hda9 /other-dist
main # chroot /other-dist /bin/bash
]]></screen>
        <para/>
      </section>
      <section>
        <title>Build packages under chroot</title>
        <para>There is a more specialized chroot package, <code>pbuilder</code>, which constructs a chroot system and builds a package inside the chroot.  It is an ideal system to use to check that a package's build-dependencies are correct, and to be sure that unnecessary and wrong build dependencies will not exist in the resulting package. </para>
        <para/>
      </section>
      <section>
        <title>Other virtualization tools</title>
        <para>There are several system <ulink url="http://en.wikipedia.org/wiki/Virtualization">virtualization</ulink> and <ulink url="http://en.wikipedia.org/wiki/Emulator">emulation</ulink> related packages in Debian beyond simple <ulink url="http://en.wikipedia.org/wiki/Chroot">chroot</ulink>. </para>
        <table>
          <caption/>
          <tgroup cols="4">
            <colspec colname="xxx1"/>
            <colspec colname="xxx2"/>
            <colspec colname="xxx3"/>
            <colspec colname="xxx4"/>
            <tbody>
              <row>
                <entry>
                  <para> List of virtualization tools </para>
                </entry>
                <entry>
                  <para> 1 </para>
                </entry>
                <entry>
                  <para> 2 </para>
                </entry>
                <entry>
                  <para> 3 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <emphasis role="strong">package</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">pocon</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">size</emphasis>
                  </para>
                </entry>
                <entry>
                  <para>
                    <emphasis role="strong">description</emphasis>
                  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>schroot</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Specialized tool for executing Debian binary packages in chroot </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>sbuild</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Tool for building Debian binary packages from Debian sources </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>pbuilder</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Personal package builder for Debian packages </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>debootstrap</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Bootstrap a basic Debian system (written in sh) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>cdebootstrap</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Bootstrap a Debian system (written in C) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>rootstrap</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> A tool for building complete Linux filesystem images </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>user-mode-linux</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/User-mode_Linux">User-mode Linux</ulink> (kernel) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>xen-tools</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> Tools to manage debian <ulink url="http://en.wikipedia.org/wiki/Xen">XEN</ulink> virtual server </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>bochs</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Bochs">Bochs</ulink>: IA-32 PC emulator </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>qemu</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Qemu">Qemu</ulink>: fast generic processor emulator </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>virtualbox-ose</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/VirtualBox">VirtualBox</ulink>: x86 virtualization solution on i386 and amd64 </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>wine</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Wine_(software)">Wine</ulink>: Windows API Implementation (standard suite) </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>dosbox</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/DOSBox">DOSBox</ulink>: x86 emulator with Tandy/Herc/CGA/EGA/VGA/SVGA graphics, sound and DOS </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>util-vserver</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/Linux-VServer">Linux-VServer</ulink> virtual private servers - user-space tools </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>vzctl</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/OpenVZ">OpenVZ</ulink> server virtualization solution - control tools  </para>
                </entry>
              </row>
              <row>
                <entry>
                  <para>
                    <code>vzquota</code>
                  </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para> - </para>
                </entry>
                <entry>
                  <para><ulink url="http://en.wikipedia.org/wiki/OpenVZ">OpenVZ</ulink> server virtualization solution - quota tools </para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
        <para>See Wikipedia article <ulink url="http://en.wikipedia.org/wiki/Comparison_of_virtual_machines">http://en.wikipedia.org/wiki/Comparison_of_virtual_machines</ulink> for detail comparison of different virtualization solutions. </para>
      </section>
    </section>
  </section>
</article>