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<chapter id="other-useful-applications" status="review">
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<title>Other Useful Applications</title>
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There are many very useful applications developed by the Ubuntu Server Team,
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and others that are well integrated with Ubuntu Server Edition, that might
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not be well known. This chapter will showcase some useful applications that can
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make administering an Ubuntu server, or many Ubuntu servers, that much easier.
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<sect1 id="update-motd" status="review">
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<title>Update MOTD</title>
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When logging into an Ubuntu server you may have noticed the informative Message Of The Day (MOTD). This information
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is obtained and displayed using a couple of packages:
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<emphasis>landscape-common:</emphasis> provides the core libraries of <application>landscape-client</application>,
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which can be used to manage systems using the web based <emphasis>Landscape</emphasis> application. The package includes
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the <application>/usr/bin/landscape-sysinfo</application> utility which is used to gather the information displayed
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<emphasis>update-motd:</emphasis> is used to automatically update the MOTD via <application>cron</application>.
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The <application>update-motd</application> utility has several options to further customize the MOTD:
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<emphasis>--disable:</emphasis> prevents automatic updates of the MOTD. Using this option creates the
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<filename>/var/lib/update-motd/disabled</filename> file, which if present stops <application>update-motd</application>
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from modifying <filename>/etc/motd</filename>.
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<emphasis>--enable:</emphasis> enables the automatic MOTD updates. If <filename>/var/lib/update-motd</filename>
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is present it will be removed.
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<emphasis>--force:</emphasis> does a one time update of <filename>/etc/motd</filename>, overriding <application>update-motd</application>
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if it has been disabled.
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<emphasis>d, hourly, weekly, monthly:</emphasis> option will run the scripts in <filename>/etc/update-motd.d/</filename> (default),
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<filename>/etc/update-motd.d/hourly</filename>, <filename>/etc/update-motd.d/weekly</filename>, or
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<filename>/etc/update-motd.d/monthly</filename> respectively.
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<application>update-motd</application> executes the scripts in <filename>/etc/update-motd.d</filename> in order based on the number
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prepended to the script. Separate <application>cron</application> scripts execute every ten minutes, hourly, weekly, and monthly
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running the corresponding scripts in <filename>/etc/update-motd.d</filename>. The output of the scripts is written to
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<filename>/var/run/update-motd/</filename>, keeping the numerical order, then concatenated with
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<filename>/etc/motd.tail</filename> and written to <filename>/etc/motd</filename>.
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You can add your own dynamic information to the MOTD. For example, to add local weather information:
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First, install the <application>weather-util</application> package:
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<command>sudo apt-get install weather-util</command>
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The <application>weather</application> utility uses METAR data from the National Oceanic and Atmospheric Administration
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and forecasts from the National Weather Service. In order to find local information you will need the 4-character ICAO
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location indicator. This can be determined by browsing to the
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<ulink url="http://www.weather.gov/tg/siteloc.shtml">National Weather Service</ulink> site.
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Although the National Weather Service is a United States government agency there are weather stations available world wide.
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However, local weather information for all locations outside the U.S. may not be available.
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Create <filename>/usr/local/bin/local-weather</filename>, a simple shell script to use
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<application>weather</application> with your local ICAO indicator:
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##########################################################################
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# Prints the local weather to /var/run/update-motd/60-local-weather
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##########################################################################
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# Replace KINT with your local weather station.
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# Local stations can be found here: http://www.weather.gov/tg/siteloc.shtml
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echo "" > /var/run/update-motd/60-local-weather
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weather -i KINT >> /var/run/update-motd/60-local-weather
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Make the script executable:
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<command>sudo chmod 755 /usr/local/bin/local-weather</command>
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Next, create a symlink to <filename>/etc/update-motd.d/60-local-weather</filename>:
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<command>sudo ln -s /usr/local/bin/local-weather /etc/update-motd.d/60-local-weather</command>
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Finally, update the MOTD:
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<command>sudo update-motd</command>
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You should now be greeted with some useful information, and some information about the local weather that may not be
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quite so useful. Hopefully the <application>local-weather</application> example demonstrates the flexibility of
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<application>update-motd</application>.
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<sect1 id="etckeeper" status="review">
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<title>etckeeper</title>
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<application>etckeeper</application> allows the contents of <filename role="directory">/etc</filename> be easily stored in
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Version Control System (VCS) repository. It hooks into <application>apt</application> to automatically commit changes to
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<filename>/etc</filename> when packages are installed or upgraded. Placing <filename>/etc</filename> under version control
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is considered an industry best practice, and the goal of <application>etckeeper</application> is to make this process as
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painless as possible.
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Install <application>etckeeper</application> by entering the following in a terminal:
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<command>sudo apt-get install etckeeper</command>
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The main configuration file, <filename>/etc/etckeeper/etckeeper.conf</filename>, is fairly simple. The main options being which
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VCS and which package management system to use. By default <application>etckeeper</application> is configured to use
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<application>bzr</application> for version control, <application>apt</application> for high level package mangement, and
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<application>dpkg</application> for low level package management.
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With the package installed, it is time to initialize the repository. In a terminal enter:
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<command>sudo etckeeper init</command>
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Next, commit the files to the repository:
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<command>sudo etckeeper commit "initial import"</command>
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Using the VCS commands you can view log information about files in <filename>/etc</filename>:
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<command>sudo bzr log /etc/passswd</command>
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To demonstrate the integration with the package management system, install <application>postfix</application>:
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<command>sudo apt-get install postfix</command>
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When the installation is finished, all the <application>postfix</application> configuration files should be committed to the
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<computeroutput>Committing to: /etc/
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added network/if-down.d/postfix
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added network/if-up.d/postfix
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added postfix/dynamicmaps.cf
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added postfix/main.cf
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added postfix/master.cf
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added postfix/post-install
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added postfix/postfix-files
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added postfix/postfix-script
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added ppp/ip-down.d/postfix
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added ppp/ip-up.d/postfix
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added rc0.d/K20postfix
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added rc1.d/K20postfix
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added rc2.d/S20postfix
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added rc3.d/S20postfix
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added rc4.d/S20postfix
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added rc5.d/S20postfix
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added rc6.d/K20postfix
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added resolvconf/update-libc.d
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added resolvconf/update-libc.d/postfix
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added rsyslog.d/postfix.conf
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added ufw/applications.d/postfix
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Committed revision 2.</computeroutput>
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For an example of how <application>etckeeper</application> tracks manual changes, add new a host to <filename>/etc/hosts</filename>.
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Using <application>bzr</application> you can see which files have been modified:
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<command>sudo bzr status /etc/</command>
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<computeroutput>modified:
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hosts</computeroutput>
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Now commit the changes:
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<command>sudo etckeeper commit "new host"</command>
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For more information on <application>bzr</application> see <xref linkend="bazaar"/>.
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<sect1 id="screen-profiles" status="review">
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<title>Screen Profiles</title>
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One of the most useful applications for any system administrator is <application>screen</application>. It allows the execution
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of multiple shells in one terminal. To make some of the advanced <application>screen</application> features more
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user friendly, and provide some useful information about the system, the <application>screen-profiles</application> package was
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When executing <application>screen</application> for the first time you will be presented with the
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<application>screen-profiles-helper</application> menu. This menu will allow you to:
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<listitem><para>View the Help menu</para></listitem>
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<listitem><para>Change the key binding set</para></listitem>
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<listitem><para>Change screen profiles</para></listitem>
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<listitem><para>Change the escape sequence</para></listitem>
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<listitem><para>Create new screen windows</para></listitem>
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<listitem><para>Manage the default windows</para></listitem>
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<listitem><para>Install screen by default at login</para></listitem>
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The <emphasis>key bindings</emphasis> determine such things as the escape sequence, new window, change window, etc. There
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are two key binding sets to choose from <emphasis>common</emphasis> and <emphasis>none</emphasis>. If you wish to use the
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original key bindings choose the <emphasis>none</emphasis> set.
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The Ubuntu <application>screen-profiles</application> provide a menu which displays the Ubuntu release, processor information,
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memory information, and the time and date. The effect is similar to a desktop menu. When a profile is selected it will be
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symlinked to <filename>~/.screenrc</filename>. The <application>select-screen-profile</application> utility can also be used
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to change profiles, in a terminal enter:
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<command>select-screen-profile -s ubuntu-light</command>
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The <emphasis>plain</emphasis> profile will change <application>screen</application> back to the defaults, which does not include
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the information menu at the bottom.
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Using the <emphasis>"Install screen by default at login"</emphasis> option will cause screen to be executed any time a terminal is opened.
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Changes made to <application>screen</application> are on a per user basis, and will not affect other users on the system.
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One difference when using screen is the <emphasis>scrollback</emphasis> mode. If you are using one of the Ubuntu profiles press the
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<emphasis>F7</emphasis>, or <emphasis>Ctrl+a+[</emphasis> if not, to enter scrollback mode. Scrollback mode allows you to navigate
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past output using <emphasis>vi</emphasis> like commands. Here is a quick list of movement commands:
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<listitem><para><emphasis>h</emphasis> - Move the cursor left by one character</para></listitem>
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<listitem><para><emphasis>j</emphasis> - Move the cursor down by one line</para></listitem>
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<listitem><para><emphasis>k</emphasis> - Move the cursor up by one line</para></listitem>
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<listitem><para><emphasis>l</emphasis> - Move the cursor right by one character</para></listitem>
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<listitem><para><emphasis>0</emphasis> - Move to the beginning of the current line</para></listitem>
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<listitem><para><emphasis>$</emphasis> - Move to the end of the current line</para></listitem>
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<listitem><para><emphasis>G</emphasis> - Moves to the specified line (defaults to the end of the buffer)</para></listitem>
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<listitem><para><emphasis>C-u</emphasis> - Scrolls a half page up</para></listitem>
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<listitem><para><emphasis>C-b</emphasis> - Scrolls a full page up</para></listitem>
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<listitem><para><emphasis>C-d</emphasis> - Scrolls a half page down</para></listitem>
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<listitem><para><emphasis>C-f</emphasis> - Scrolls the full page down</para></listitem>
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<listitem><para><emphasis>/</emphasis> - Search forward</para></listitem>
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<listitem><para><emphasis>?</emphasis> - Search backward</para></listitem>
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<listitem><para><emphasis>n</emphasis> - Moves to the next match, either forward or backword</para></listitem>
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<sect1 id="other-app-references" status="review">
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<title>References</title>
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See the <ulink url="http://manpages.ubuntu.com/manpages/jaunty/en/man1/update-motd.1.html">update-motd man page</ulink> for
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more options available to <application>update-motd</application>.
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The Debian Package of the Day
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<ulink url="http://debaday.debian.net/2007/10/04/weather-check-weather-conditions-and-forecasts-on-the-command-line/">weather</ulink>
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article has more details about using the <application>weather</application>utility.
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See the <ulink url="http://kitenet.net/~joey/code/etckeeper/">etckeeper</ulink> site for more details on using
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<application>etckeeper</application>.
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For the latest news and information about <application>bzr</application> see the <ulink url="http://bazaar-vcs.org/">bzr</ulink> web site.
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For more information on <application>screen</application> see the <ulink url="http://www.gnu.org/software/screen/">screen web site</ulink>.
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Also, see the <application>screen-profiles</application> <ulink url="https://launchpad.net/screen-profiles">project page</ulink> for more
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