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.
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/>
SEE ALSO
casper-snapshot(1),initramfs-tools(8),make-live(8),make-live.conf(5)
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).