Provided by: casper_1.470_amd64 bug


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


       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 overlay, for
       debian like systems to boot from.


              This enables a special "serial" login shell (experimental).

              uses xdebconfigurator, if present on the rootfs, to  configure  X  instead  of  the
              standard procedure (experimental).

              Let you skip the file system check on boot.

       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|keyboard-
       configuration/layoutcode}=LAYOUT      ,      {kvariant|console-setup/variantcode|keyboard-
       configuration/variantcode}=VARIANT       ,       {kmodel|console-setup/modelcode|keyboard-
       configuration/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).

              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).

              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.

              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

              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.

              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

              Sets the  path  to  the  leaf  layer  of  an  overlay-compatible  multi-layer  live
              filesystem on the medium. By default, it is not set and multi layer is disabled and
              falls back to the default behaviour of casper. A relative path uses  "live-mediate-
              path"  as root directory. All the layer images of the same hierarchy must be in the
              same directory.

       locale=LOCALE | debian-installer/locale=LOCALE|debian-installer/language="LANG
              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).  if
              debian-installer/language   is   set,   it   will  choose  the  appropriate  locale
              corresponding to this language (it,fr,us,...)

              Add a ubiquity hook to install driver-updates to the target system.

              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. If url  method  is  chosen,
              "url=" parameter should point to the location of the ".iso" that will be downloaded
              and mounted. Note "url=" on the commandline alone, by  default  sets  "netboot=url"
              method too.

              This  tells  casper  the  download  location  of the installer ISO. The ISO will be
              downloaded and mounted. Networking is required for this option to work,  which  can
              be  configured  with  "ip="  option.  Note,  setting  this  option,  will  also set
              "netboot=url" method.

              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

              disables  the  above mentioned "persistent" feature, useful if the bootloader (like
              syslinux) has been installed with persistent enabled.

              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.

              Redirect output to tty of choice for debugging purposes in live sessions

              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.

              Start up to text-mode shell prompts, disabling the graphical user interface.

              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.

              A path to a file present on the rootfs could be used to preseed debconf database.

              Bring up the network while running preseed/early_command.

              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

              Check that the discovered medium matches UUID rather than the default UUID embedded
              in the initramfs.

              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.

              Do not prompt to eject the CD on reboot.

              Adding  this  parameter  will  tune  the   graphic   configuration   to   different
              accessibility  needs.   access=v1  for  Lesser  Visual  Impairment,  access=v2  for
              Moderate Visual Impairment, access=v3 for  Blindness,  access=m1  for  Minor  motor
              difficulties and access and m2 for Motor difficulties with pointing devices.

              Adding this parameter will enable graphic configuration for screen reader.

              Create  basic  xorg.conf  to  force  VESA mode only which could help if no suitable
              video driver is available


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


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


       Debian Live project <>




       casper  was  written  by  Tollef   Fog   Heen   <>,   Matt   Zimmerman
       <>, and Marco Amadori <>.

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