+ (see <xref linkend="QuickStart" />). </para>
+
+ <para> The preferred option for changing the configuration is to
+ use the <command>plc-config-tty</command> tool. This tool comes
+ with the root image, so you need to have it mounted first. The
+ full set of applicable variables is described in <xref
+ linkend="VariablesDevel" />, but using the <command>u</command>
+ guides you to the most useful ones. Note that if you
+ plan on federating with other PLCs, <emphasis> it is strongly
+ recommended that you change the <command> PLC_NAME
+ </command> and <command> PLC_SLICE_PREFIX </command>
+ settings. </emphasis>
+ Here is sample session:
+ </para>
+
+ <example><title>Using plc-config-tty for configuration:</title>
+ <programlisting><![CDATA[# service plc mount
+Mounting PLC: [ OK ]
+# chroot /plc/root su -
+<plc> # plc-config-tty
+Config file /etc/planetlab/configs/site.xml located under a non-existing directory
+Want to create /etc/planetlab/configs [y]/n ? y
+Created directory /etc/planetlab/configs
+Enter command (u for usual changes, w to save, ? for help) u
+== PLC_NAME : [PlanetLab Test] OneLab
+== PLC_SLICE_PREFIX : [pl] thone
+== PLC_ROOT_USER : [root@localhost.localdomain] root@onelab-plc.inria.fr
+== PLC_ROOT_PASSWORD : [root] plain-passwd
+== PLC_MAIL_ENABLED : [false] true
+== PLC_MAIL_SUPPORT_ADDRESS : [root+support@localhost.localdomain] support@one-lab.org
+== PLC_BOOT_HOST : [localhost.localdomain] onelab-plc.inria.fr
+== PLC_NET_DNS1 : [127.0.0.1] 138.96.250.248
+== PLC_NET_DNS2 : [None] 138.96.250.249
+Enter command (u for usual changes, w to save, ? for help) w
+Wrote /etc/planetlab/configs/site.xml
+Merged
+ /etc/planetlab/default_config.xml
+and /etc/planetlab/configs/site.xml
+into /etc/planetlab/plc_config.xml
+You might want to type 'r' (restart plc) or 'q' (quit)
+Enter command (u for usual changes, w to save, ? for help) r
+==================== Stopping plc
+...
+==================== Starting plc
+...
+Enter command (u for usual changes, w to save, ? for help) q
+<plc> # exit
+#
+]]></programlisting>
+ </example>
+
+ <para>If you used this method for configuring, you can skip to
+ the <xref linkend="LoginRealUser" />. As an alternative to using
+ <command>plc-config-tty</command>, you may also use a text
+ editor, but this requires some understanding on how the
+ configuration files are used within myplc. The
+ <emphasis>default</emphasis> configuration is stored in a file
+ named <filename>/etc/planetlab/default_config.xml</filename>,
+ that is designed to remain intact. You may store your local
+ changes in any file located in the <filename>configs/</filename>
+ sub-directory, that are loaded on top of the defaults. Finally
+ the file <filename>/etc/planetlab/plc_config.xml</filename> is
+ loaded, and the resulting configuration is stored in the latter
+ file, that is used as a reference.</para>
+
+ <para> Using a separate file for storing local changes only, as
+ <command>plc-config-tty</command> does, is not a workable option
+ with a text editor because it would involve tedious xml
+ re-assembling. So your local changes should go in
+ <filename>/etc/planetlab/plc_config.xml</filename>. Be warned
+ however that any change you might do this way could be lost if
+ you use <command>plc-config-tty</command> later on. </para>
+
+ <para>This file is a self-documenting configuration file written
+ in XML. Variables are divided into categories. Variable
+ identifiers must be alphanumeric, plus underscore. A variable is
+ referred to canonically as the uppercase concatenation of its
+ category identifier, an underscore, and its variable
+ identifier. Thus, a variable with an <literal>id</literal> of