Important: In order to easily avoid the questions that would normally appear before the preseed- ing occurs, you can start the installer in “auto” mode. This delays questions that would normally be asked too early for preseeding (i.e. language, country and keyboard selection) until after the network comes up, thus allowing them to be preseeded. It also runs the installation at critical priority, which avoids many unimportant questions. See Section B.2.3 for details. 

## B.1.2. Limitations 

Although most questions used by debian-installer can be preseeded using this method, there are some notable exceptions. You must (re)partition an entire disk or use available free space on a disk; it is not possible to use existing partitions. 

## B.1.3. Debconf basics 

Preseeding makes use of the debconf framework. This framework is the preferred mechanism used in Ubuntu to interact with the user when configuring packages and also forms the heart of debian-installer . In the debconf framework questions or dialogs are based on templates . 

There are different types of templates for different types of questions. The actual questions are “generated” from templates at runtime; multiple questions can use the same template. 

The following types of templates are relevant for preseeding. 

• string: allows the user to type any value 

• password: similar to string but the value typed is not displayed 

• boolean: for yes/no or true/false type of questions 

• select: allows the user to select one option from a list 

• multiselect: allows the user to select zero, one or more options from a list 

• note: used to display a message 

In debian-installer templates are stored in a readable file /var/cache/debconf/templates.dat . This file contains all fixed text and all translations. It can also contain a default value for the template. The fixed text can include variables that will be replaced at runtime. 

Another readable file /var/cache/debconf/questions.dat is used to store the values for vari- ables and the answers given to questions. A question always refers to the template used to ask it. 

For obvious security reasons the values for questions of type “password” are stored in a separate, non-readable file in the same directory. 

## B.2. Using preseeding 

You will first need to create a preconfiguration file and place it in the location from where you want to use it. Creating the preconfiguration file is covered later in this appendix. Putting it in the correct location is fairly straightforward for network preseeding or if you want to read the file off a floppy or usb-stick. If you want to include the file on a CD or DVD, you will have to remaster the ISO image. 

How to get the preconfiguration file included in the initrd is outside the scope of this document; please consult the developers’ documentation for debian-installer . 

