Question

You can make the installer display an error message to the user if certain conditions are met using a throwError action. Those conditions are expressed by rules as explained in the conditional evaluation chapter of the product documentation included with InstallBuilder. If used inside a parameter <validationActionList> section, an error message will be displayed to the user and the user will be prompted again for the required information. If used in any other action list section, such as <preInstallationActionList>, it will display an error message to the user and the application will exit. The following example code, when placed in <preInstallationActionList> will throw an error and abort the installation if the Apache configuration file is not writable by the current user:

       <throwError>
          <text>The Apache configuration file is not writable by the current user</text>
          <ruleList>
            <fileTest>
              <path>/usr/local/apache/conf/httpd.conf</path>
              <condition>not_writable</condition>
            </fileTest>
          </ruleList>
       </throwError>