Methods for Running Windows Setup

Windows Setup can perform Windows installations by using interactive or unattended installation methods.

Interactive Windows Setup

In this method, a user must select where to install Windows, read and accept the Microsoft Software License Terms, and apply a product key.

This method is useful for small-scale rollouts or individual installations. By using the default image from Microsoft, interactive Windows Setup does not require any preparatory work, such as creating answer files or capturing Windows images. It is possible to use interactive Windows Setup in conjunction with creating and capturing custom Windows images.

You can interactively install or upgrade Windows by using the Windows product media or from a network location after you store and share the installation files from the Windows product media. Interactive setup requires input from users, including destination drive, user names, and time zones.

Unattended Windows Setup

Windows Setup works with an unattended installation answer file to automate online installations and customizations of Windows. This method is useful for large-scale rollouts and for achieving consistency and precision in the configuration of each computer.

Unattended installation requires the creation of one or more answer files containing customizations for an installation. For example, you can change the Internet Explorer configuration or partition and format hard disks. For information about creating answer files with Windows System Image Manager (Windows SIM), see the Windows System Image Manager Technical Reference.

There are two ways that Windows Setup applies answer files: explicitly specifying an answer file or implicitly searching for an answer file.

Explicitly Specifying an Answer File

You can explicitly specify an answer file by using the **setup.exe /unattend:**filename command.

In this example, filename is the local or UNC path for the answer file. For more information, see Windows Setup Command-Line Options.

This answer file is used to configure the Windows installation. Because reboots are required during Setup, a copy of this answer file is cached on the computer.

Implicitly Searching for an Answer File

If an answer file is not specified, Windows Setup implicitly searches for an answer file in several different locations. The locations include a previously cached answer file, an answer file at the root of a drive, and other locations. The complete list of valid search paths is listed in the Implicit Answer File Search Order section below.

Windows Setup implicitly searches for an answer file every time a configuration pass starts.

There is an order of precedence when Windows Setup searches for an answer file. If an answer file is found in one of the valid locations, it must include a valid configuration pass. If an answer file is found and it includes no settings for the given configuration pass that is running, that answer file will be ignored.

Implicit Answer File Search Order

Windows Setup identifies and logs all available answer files based on the search order. The answer file with the highest precedence is used. The answer file is validated and then cached to the computer. Valid answer files are cached to the $Windows.~BT\Sources\Panther directory during the windowsPE and offlineServicing passes. After the Windows installation is extracted to the hard disk, the answer file is cached to %WINDIR%\panther.

The following table shows the implicit answer file search order.

Search Order	Location	Description
1	Registry HKLM\System\Setup!UnattendFile	Specifies a pointer in the registry to an answer file. The answer file is not required to be named Unattend.xml.
2	%WINDIR%\Panther\Unattend	The name of the answer file must be Unattend.xml or Autounattend.xml. Note   Windows Setup only searches this directory on downlevel installations. If Windows Setup starts from Windows PE, the %WINDIR%\Panther\Unattend directory is not searched.
3	%WINDIR%\Panther	Windows Setup caches answer files to this location. Important Do not overwrite the answer files in these directories.
4	Removable read/write media in order of drive letter, at the root of the drive.	Removable read/write media in order of drive letter, at the root of the drive. The name of the answer file must be Unattend.xml or Autounattend.xml, and the answer file must be located at the root of the drive.
5	Removable read-only media in order of drive letter, at the root of the drive.	Removable read-only media in order of drive letter, at the root of the drive. The name of the answer file must be Unattend.xml or Autounattend.xml, and must be located at the root of the drive.
6	windowsPE and offlineServicing passes: \Sources directory in a Windows distribution All other passes: %WINDIR%\System32\Sysprep	In the windowsPE and offlineServicing passes, the name of the answer file must be Autounattend.xml. For all other configuration passes, the file name must be Unattend.xml.
7	%SYSTEMDRIVE%	The answer file name must be Unattend.xml or Autounattend.xml

Sensitive Data in Answer Files

Setup removes sensitive data in the cached answer file at the end of the current configuration pass.

However, if an answer file is embedded in a higher precedence location than the cached answer file, then the cached answer may be overwritten at the beginning of each subsequent configuration pass if the embedded answer file matches the implicit search criteria. For example, if an answer file is embedded at %WINDIR%\Panther\Unattend\Unattend.xml, the embedded answer file will replace the cached answer file at the beginning of each configuration pass. For example, if the embedded answer file specifies both the specialize and oobeSystem passes, then the embedded answer file is discovered for the specialize pass, cached, processed, and sensitive data is cleared. The embedded answer file is discovered again during the oobeSystem pass and cached again. As a result, the sensitive data for the specialize pass is no longer cleared. Sensitive data for previously processed passes will not be cleared again. Unless the cached answer file must be overridden, it is recommended that answer files be embedded at a lower precedence location.

Microsoft recommends that you delete all the answer files on a Windows installation before delivering the computer to a customer. This includes any embedded answer files as well as the cached answer file. However, if you have unprocessed settings in the oobeSystem configuration pass that you intend to run when an end user starts the computer, do not delete the cached answer file.

You can add a command to the Setupcomplete.cmd command script that deletes any cached or embedded answer files on the computer. For more information, see Add a Custom Script to Windows Setup.

Windows Setup Annotates Configuration Passes in an Answer File

After a configuration pass is processed, Windows Setup annotates the cached answer file to indicate that the pass has been processed. If the configuration pass is entered again and the cached answer file has not been replaced or updated in the interim, the answer file settings are not processed a second time. Instead, Windows Setup will search for implicit Unattend.xml files that are at a lower precedence location than the cached Unattend.xml file.

For example, you can install Windows with an answer file that contains RunSynchronous commands in the specialize pass. During installation, the specialize pass runs and the RunSynchronous commands execute. After installation, run the sysprep /generalize command. If there is no answer file in a higher precedence than the cached answer file or an answer file was not explicitly passed to Sysprep, Setup runs specialize the next time the computer boots. Because the cached answer file contains an annotation that the settings for that pass were already applied, the RunSynchronous commands do not execute.

Implicit Answer File Search Example

The following examples help describe the behavior of implicit answer file searches.

Answer files named Autounattend.xml are automatically discovered by Windows Setup

1. Create an answer file named Autounattend.xml that includes settings in the windowsPE pass.
2. Copy Autounattend.xml to a removable media device.
3. Configure the BIOS of your computer to boot from CD or DVD.
4. Boot the Windows Vista product DVD.
5. Insert the floppy disk while Windows is booting.
   Windows Setup starts and automatically identifies Autounattend.xml as a valid answer file. Because the answer file uses a valid file name (Autounattend.xml), is located in one of the valid search paths (the root of A), and includes valid settings for the current configuration pass (windowsPE), this answer file is used.
   The answer file is cached to the computer. If there are no additional answer files discovered in later passes, the cached answer file is used throughout Windows Setup.

Answer files are discovered in order of precedence in predefined search paths

1. Install Windows with an answer file by using the steps in the previous scenario. The answer file used to install Windows is cached to the system in the %WINDIR%\Panther directory.

2. Copy an Unattend.xml file to the %WINDIR%\System32\Sysprep directory.
   This answer file has settings in the generalize pass.

3. Run the sysprep /generalize command to create a reference image.
   Because the %WINDIR%\System32\Sysprep directory is in the implicit search paths, the answer file copied to this directory is found. However, an answer file that was used to install Windows is still cached on the computer and contains settings for the generalize pass. This cached answer file has a higher precedence than the one copied to the Sysprep directory. The cached answer file is used.

To use the new answer file, copy it to a directory of a higher precedence than the cached answer file or you can specify the answer file by using the **/unattend** option. For example:  

    sysprep /generalize /unattend:C:\MyAnswerFile.xml

Answer files must include a valid configuration pass

1. Copy an Unattend.xml file to a floppy disk.
   The Unattend.xml file has settings only for the auditSystem and auditUser configuration passes.
2. On an installed Windows operating system, run the sysprep /generalize /oobe command.
   Even though the answer file is available in one of the implicit search paths, the Unattend.xml file is ignored because it does not contain a valid pass for the generalize configuration pass.