casper

SYNOPSIS

BOOT=casper As kernel parameter boot prompt.

Casper is a hook for initramfs-tools used to generate an initramfs capable to boot live systems as those created by make-live. This includes the Debian-Live isos, netboot tarballs, and usb stick images and Ubuntu live cds. At boot time it will look for a (read-only) media containing a "/casper" directory where a root filesystems (often a compressed squashfs) is stored. If found, it will create a writable environment, using unionfs, for debian like systems to boot from.

RECOGNIZED BOOT OPTIONS

casper-getty: This enables a special "serial" login shell (experimental).
xdebconf: uses xdebconfigurator, if present on the rootfs, to configure X instead of the standard procedure (experimental).
hostname=HOSTNAME , userfullname=USERFULLNAME , username=USERNAME: Those parameters lets you override values read from the config file.
{keyb|kbd-chooser/method}=KEYBOARD , {klayout|console-setup/layoutcode}=LAYOUT , {kvariant|console-setup/variantcode}=VARIANT , {kmodel|console-setup/modelcode}=CODE , koptions=OPTIONS: Configure the running keyboard as specified, if this one misses casper behaves as if "keyb=us" was specified. It will be interfered from "locale=" if locale is only 2 lowecase letters as a special case. You could also specify console layout, variant, code, and options (no defaults).
ip=IFACE,ADDRESS,NETMASK,GATEWAY[:IFACE,ADDRESS,NETMASK,GATEWAY]*: Let you specify the name(s) and the options of the interface(s) that should be configured at boot time. Do not specify this if you want to use dhcp (default).
ip[=frommedia]: If this variable is set, dhcp and static configuration are just skipped and the system will use the (must be) media-preconfigured /etc/network/interfaces instead.
{live-media|bootfrom}=DEVICE: If you specify one of this two equivalent forms, casper will first try to find this device for the "/casper" directory where the read-only root filesystem should reside. If it did not find something usable, the normal scan for block devices is performed.
live-media-offset=BYTES: This way you could tell casper that your image starts at offset BYTES in the above specified or autodiscovered device, this could be useful to hide the debian-live iso or image inside another iso or image, to create "clean" images.
live-media-path=PATH: Sets the path to the live filesystem on the medium. By default, it is set to "/casper" and you should not change that unless you have customized your media accordingly.
locale=LOCALE | debian-installer/locale=LOCALE: Configure the running locale as specified, if not present the live-media rootfs configured locale will be used and if also this one misses casper behave as "locale=en_US.UTF-8" was specified. If only 2 lowercase letter are specified (like "it"), the "maybe wanted" locale is generated (like it:IT.UTF-8), in this case if also "keyb=" is unspecified is set with those 2 lowercase letters (keyb=it).
netboot[=nfs|cifs]: This tells casper to perform a network mount. The parameter "nfsroot=" (with optional "nfsopts="), should specify where is the location of the root filesystem. With no args, will try cifs first, and if it fails nfs.
persistent: Casper will look for persistent and snapshot partitions or files labeled "casper-rw", "home-rw", and files called "casper-sn*", "home-sn*" and will try to, in order: mount as /cow the first, mount the second in /home, and just copy the contents of the latter in appropriate locations (snapshots). Snapshots will be tried to be updated on reboot/shutdown. Look at casper-snapshot(1) for more informations.
nopersistent: disables the above mentioned "persistent" feature, useful if the bootloader (like syslinux) has been installed with persistent enabled.
persistent-path=PATH: Casper will look for persistency files in the root directory of a partition. With this parameter, the path can be configured so that you can have multiple directories on the same partition to store persistency files.
showmounts: This parameter will make casper to show on "/" the ro filesystems (mostly compressed) on /casper. This is not enabled by default because could lead to problems by applications like "mono" which store binary paths on installation.
textonly: Start up to text-mode shell prompts, disabling the graphical user interface.
todisk=DEVICE: Adding this parameter, casper will try to copy the entire read-only media to the specified device before mounting the root filesystem. It probably needs a lot of free space. Subsequent boots should then skip this step and just specify the "live-media=DEVICE" boot parameter with the same DEVICE used this time.
toram: Adding this parameter, casper will try to copy the whole read-only media to the computer's RAM before mounting the root filesystem. This could need a lot of ram, according to the space used by the read-only media.
{preseed/file|file}=FILE: A path to a file present on the rootfs could be used to preseed debconf database.
preseed/allow-network=true: Bring up the network while running preseed/early_command.
package/question=VALUE: All debian installed packages could be preseeded from command-line that way, beware of blanks spaces, they will interfere with parsing, use a preseed file in this case.
uuid=UUID: Check that the discovered medium matches UUID rather than the default UUID embedded in the initramfs.
ignore_uuid: Do not check that any UUID embedded in the initramfs matches the discovered medium. casper may be told to generate a UUID by setting CASPER_GENERATE_UUID=1 when building the initramfs.
noprompt: Do not prompt to eject the CD on reboot.