Ubuntu Manpage: casper - a hook for initramfs-tools to boot live systems.

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NAME

       casper - a hook for initramfs-tools to boot live systems.

SYNOPSIS

       BOOT=casper As kernel parameter boot prompt.

DESCRIPTION

       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.

FILES

       /etc/casper.conf some variables can be configured via this config file.

BUGS

       casper works fully on amd64, i386 and ppc, it should also run on other archs.

HOMEPAGE

       Debian Live project <http://live.debian.net/>

AUTHOR

       casper  was  written  by  Tollef Fog Heen <tfheen@canonical.com>, Matt Zimmerman <mdz@canonical.com>, and
       Marco Amadori <marco.amadori@gmail.com>.

       This manual page was written by Marco Amadori <marco.amadori@gmail.com>,
              for the Debian project (but may be used by others).