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       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 unionfs, 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).

       hostname=HOSTNAME , userfullname=USERFULLNAME , username=USERNAME
              Those parameters lets you override values read from  the  config

       {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).

              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 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).

              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.

              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.

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

              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.

              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

       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 case.

              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.


       /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


       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).