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The installation system recognizes a few additional boot parameters1 which may be useful.
A number of parameters have a “short form” (or alias) that helps avoid the limitations of the kernel command line options and makes entering the parameters easier. If a parameter has a short form, it will be listed in brackets behind the (normal) long form. Examples in this manual will normally use the short form too.
debconf/priority (priority)
This parameter sets the lowest priority of messages to be displayed.
The default installation uses priority=high. This means that both high and critical priority messages are shown, but medium and low priority messages are skipped. If problems are en- countered, the installer adjusts the priority as needed.
If you add priority=medium as boot parameter, you will be shown the installation menu and gain more control over the installation. When priority=low is used, all messages are shown (this is equivalent to the expert boot method). With priority=critical, the installation sys- tem will display only critical messages and try to do the right thing without fuss.
Note: In order to get asked for a VLAN configuration during the network setup a priority of
medium or low is needed.
1. With current kernels (2.6.9 or newer) you can use 32 command line options and 32 environment options. If these numbers are exceeded, the kernel will panic.
DEBIAN_FRONTEND
This boot parameter controls the type of user interface used for the installer. The current possible parameter settings are:
• DEBIAN_FRONTEND=noninteractive
• DEBIAN_FRONTEND=text
• DEBIAN_FRONTEND=newt
• DEBIAN_FRONTEND=gtk
The default frontend is DEBIAN_FRONTEND=newt. DEBIAN_FRONTEND=text may be prefer- able for serial console installs . Some specialized types of install media may only offer a limited selection of frontends, but the newt and text frontends are available on most default install media. On architectures that support it, the graphical installer uses the gtk frontend.
BOOT_DEBUG
Setting this boot parameter to 2 will cause the installer’s boot process to be verbosely logged. Setting it to 3 makes debug shells available at strategic points in the boot process. (Exit the shells to continue the boot process.)
BOOT_DEBUG=0
This is the default.
BOOT_DEBUG=1
More verbose than usual.
BOOT_DEBUG=2
Lots of debugging information.
BOOT_DEBUG=3
Shells are run at various points in the boot process to allow detailed debugging. Exit the shell to continue the boot.
INSTALL_MEDIA_DEV
The value of the parameter is the path to the device to load the Ubuntu installer from. For exam- ple,
log_host log_port
Causes the installer to send log messages to a remote syslog on the specified host and port as well as to a local file. If not specified, the port defaults to the standard syslog port 514.
lowmem
Can be used to force the installer to a lowmem level higher than the one the installer sets by default based on available memory. Possible values are 1 and 2. See also Section 6.3.1.1.
noshell
Prevents the installer from offering interactive shells on tty2 and tty3. Useful for unattended installations where physical security is limited.
debian-installer/framebuffer (fb)
Some architectures use the kernel framebuffer to offer installation in a number of languages. If framebuffer causes a problem on your system you can disable the feature using the parameter fb=false. Problem symptoms are error messages about bterm or bogl, a blank screen, or a freeze within a few minutes after starting the install.
debian-installer/theme (theme)
A theme determines how the user interface of the installer looks (colors, icons, etc.). What themes are available differs per frontend. Currently both the newt and gtk frontends only have a “dark” theme that was designed for visually impaired users. Set the theme by booting with theme=dark.
netcfg/disable_autoconfig
By default, the debian-installer automatically probes for network configuration via IPv6 autoconfiguration and DHCP. If the probe succeeds, you won’t have a chance to review and change the obtained settings. You can get to the manual network setup only in case the automatic configuration fails.
If you have an IPv6 router or a DHCP server on your local network, but want to avoid them because e.g. they give wrong answers, you can use the parameter netcfg/disable_autoconfig=true to prevent any automatic configuration of the network (neither v4 nor v6) and to enter the information manually.
disk-detect/dmraid/enable (dmraid)
Set to true to enable support for Serial ATA RAID (also called ATA RAID, BIOS RAID or fake RAID) disks in the installer. Note that this support is currently experimental. Additional information can be found on the Debian Installer Wiki (http://wiki.debian.org/DebianInstaller/).
preseed/url (url)
Specify the url to a preconfiguration file to download and use for automating the install. See Section 4.4.
preseed/file (file)
Specify the path to a preconfiguration file to load for automating the install. See Section 4.4.
preseed/interactive
Set to true to display questions even if they have been preseeded. Can be useful for testing or debugging a preconfiguration file. Note that this will have no effect on parameters that are passed as boot parameters, but for those a special syntax can be used. See Section B.5.2 for details.
auto-install/enable (auto)
Delay questions that are normally asked before preseeding is possible until after the network is configured. See Section B.2.3 for details about using this to automate installs.
finish-install/keep-consoles
During installations from serial or management console, the regular virtual consoles (VT1 to VT6) are normally disabled in /etc/inittab. Set to true to prevent this.
cdrom-detect/eject
By default, before rebooting, debian-installer automatically ejects the optical media used during the installation. This can be unnecessary if the system does not automatically boot off the CD. In some cases it may even be undesirable, for example if the optical drive cannot reinsert the media itself and the user is not there (since working from remote) to do it manually. Many slot loading, slim-line, and caddy style drives cannot reload media automatically.
Set to false to disable automatic ejection, and be aware that you may need to ensure that the system does not automatically boot from the optical drive after the initial installation.
base-installer/install-recommends (recommends)
By setting this option to false, the package management system will be configured to not automatically install “Recommends”, both during the installation and for the installed system. See also Section 6.3.4.
Note that this option allows to have a leaner system, but can also result in features being missing that you might normally expect to be available. You may have to manually install some of the recommended packages to obtain the full functionality you want. This option should therefore only be used by very experienced users.
debian-installer/allow_unauthenticated
By default the installer requires that repositories be authenticated using a known gpg key. Set to
true to disable that authentication. Warning: insecure, not recommended.
rescue/enable
Set to true to enter rescue mode rather than performing a normal installation. See Section 8.7.