syslinux - install the SYSLINUX bootloader on a FAT filesystem


   syslinux [OPTIONS] device


   Syslinux is a boot loader for the Linux operating system which operates
   off an MS-DOS/Windows FAT filesystem. It is intended to simplify first-
   time  installation  of  Linux,  and  for  creation  of rescue and other
   special-purpose boot disks.

   In order to create a bootable Linux floppy using  Syslinux,  prepare  a
   normal  MS-DOS formatted floppy. Copy one or more Linux kernel files to
   it, then execute the command:

          syslinux --install /dev/fd0

   This will alter the boot sector on the  disk  and  copy  a  file  named
   ldlinux.sys into its root directory.

   On  boot  time,  by  default,  the kernel will be loaded from the image
   named LINUX on the boot floppy.  This default can be changed,  see  the
   section on the syslinux configuration file.

   If  the  Shift  or  Alt  keys are held down during boot, or the Caps or
   Scroll locks are set, syslinux will display a  lilo(8)  -style  "boot:"
   prompt.  The  user  can  then  type  a kernel file name followed by any
   kernel parameters. The SYSLINUX bootloader does not need to know  about
   the  kernel  file in advance; all that is required is that it is a file
   located in the root directory on the disk.

   Syslinux supports the loading of  initial  ramdisks  (initrd)  and  the
   bzImage kernel format.


   -i, --install
          Install  SYSLINUX  on  a  new medium, overwriting any previously
          installed bootloader.

   -U, --update
          Install SYSLINUX on a new medium if and only  if  a  version  of
          SYSLINUX is already installed.

   -s, --stupid
          Install  a  "safe,  slow  and  stupid" version of SYSLINUX. This
          version may work on some very buggy  BIOSes  on  which  SYSLINUX
          would  otherwise  fail.   If  you find a machine on which the -s
          option is required to make it boot reliably, please send as much
          info  about  your  machine  as  you can, and include the failure

   -f, --force
          Force install even if it appears unsafe.

   -r, --raid
          RAID mode.  If boot fails, tell the BIOS to boot the next device
          in  the  boot  sequence  (usually the next hard disk) instead of
          stopping with an error  message.   This  is  useful  for  RAID-1

   -d, --directory subdirectory
          Install  the  SYSLINUX  control files in a subdirectory with the
          specified name (relative to the root directory on the device).

   -t, --offset offset
          Indicates that the filesystem is at an offset from the  base  of
          the device or file.

   --once command
          Declare a boot command to be tried on the first boot only.

   -O, --clear-once
          Clear the boot-once command.

   -H, --heads head-count
          Override the detected number of heads for the geometry.

   -S, --sectors sector-count
          Override the detected number of sectors for the geometry.

   -z, --zipdrive
          Assume zipdrive geometry (--heads 64 --sectors 32).


   Configuration file
   All  the  configurable defaults in SYSLINUX can be changed by putting a
   file called syslinux.cfg in the install directory  of  the  boot  disk.
   This  is  a  text  file in either UNIX or DOS format, containing one or
   more of the following items (case is insensitive for keywords).

   This list is out of date.

   In the configuration file blank lines and comment lines beginning  with
   a hash mark (#) are ignored.

   default kernel [ options ... ]
          Sets  the default command line. If syslinux boots automatically,
          it will act just as if the  entries  after  "default"  had  been
          typed in at the "boot:" prompt.

          If  no  DEFAULT  or  UI statement is found, or the configuration
          file is missing entirely, SYSLINUX drops  to  the  boot:  prompt
          with an error message (if NOESCAPE is set, it stops with a "boot
          failed" message; this is also  the  case  for  PXELINUX  if  the
          configuration file is not found.)

   NOTE: Until SYSLINUX 3.85, if no configuration file is present, or no
          "default"  entry  is  present  in  the  configuration  file, the
          default is "linux auto".

   Even earlier versions of SYSLINUX used to automatically
          append the string "auto" to whatever the  user  specified  using
          the  DEFAULT  command.   As  of  version 1.54, this is no longer
          true, as it caused problems when using a shell as  a  substitute
          for "init."  You may want to include this option manually.

   append options ...
          Add  one  or  more options to the kernel command line. These are
          added both for automatic and manual boots. The options are added
          at  the  very  beginning  of  the  kernel  command line, usually
          permitting explicitly entered kernel options to  override  them.
          This is the equivalent of the lilo(8)
           "append" option.

   label label
     kernel image
     append options ...
          Indicates  that  if  label  is  entered  as  the kernel to boot,
          syslinux should instead boot image, and the  specified  "append"
          options  should  be  used  instead  of the ones specified in the
          global section of the file (before the first  "label"  command.)
          The  default  for image is the same as label, and if no "append"
          is given the default is to use the global entry (if  any).   Use
          "append  -" to use no options at all.  Up to 128 "label" entries
          are permitted.

                 The "image" doesn't have to be a Linux kernel; it can  be
                 a boot sector (see below.)

   implicit flag_val
          If  flag_val is 0, do not load a kernel image unless it has been
          explicitly named in a "label" statement.  The default is 1.

   timeout timeout
          Indicates how long to wait at the "boot:" prompt  until  booting
          automatically,  in  units of 1/10 s. The timeout is cancelled as
          soon as the user types anything on the keyboard, the  assumption
          being  that  the  user  will  complete  the command line already
          begun. A timeout of zero will disable  the  timeout  completely,
          this  is also the default. The maximum possible timeout value is
          35996; corresponding to just below one hour.

   serial port [ baudrate ]
          Enables a serial port to act as the console. "port" is a  number
          (0  =  /dev/ttyS0  =  COM1, etc.); if "baudrate" is omitted, the
          baud rate defaults to  9600  bps.   The  serial  parameters  are
          hardcoded to be 8 bits, no parity, 1 stop bit.

          For  this directive to be guaranteed to work properly, it should
          be the first directive in the configuration file.

   font filename
          Load a font in .psf format before displaying any output  (except
          the  copyright  line,  which  is output as ldlinux.sys itself is
          loaded.) syslinux only loads the font onto the  video  card;  if
          the .psf file contains a Unicode table it is ignored.  This only
          works on EGA and VGA cards; hopefully it should  do  nothing  on

   kbdmap keymap
          Install  a  simple  keyboard  map. The keyboard remapper used is
          very simplistic (it simply remaps the keycodes received from the
          BIOS, which means that only the key combinations relevant in the
          default layout - usually U.S.  English  -  can  be  mapped)  but
          should  at least help people with AZERTY keyboard layout and the
          locations of = and , (two special characters used heavily on the
          Linux kernel command line.)

          The included program from the lilo(8)
           distribution can be used to create such keymaps.

   display filename
          Displays  the  indicated file on the screen at boot time (before
          the boot: prompt, if displayed). Please see the section below on
          DISPLAY  files.  If  the  file is missing, this option is simply

   prompt flag_val
          If flag_val is 0, display the "boot:" prompt only if  the  Shift
          or  Alt key is pressed, or Caps Lock or Scroll lock is set (this
          is the default).  If flag_val is 1, always display  the  "boot:"

   f1 filename
   f2 filename
   f9 filename
   f10 filename
   f11 filename
   f12 filename
          Displays the indicated file on the screen when a function key is
          pressed at the "boot:" prompt. This can  be  used  to  implement
          pre-boot  online  help  (presumably  for the kernel command line

          When using the serial console, press <Ctrl-F><digit> to  get  to
          the  help  screens, e.g. <Ctrl-F>2 to get to the f2 screen.  For
          f10-f12, hit <Ctrl-F>A, <Ctrl-F>B, <Ctrl-F>C.  For  compatiblity
          with earlier versions, f10 can also be entered as <Ctrl-F>0.

   Display file format
   DISPLAY  and  function-key  help  files are text files in either DOS or
   UNIX format (with or without <CR>). In addition, the following  special
   codes are interpreted:

   <FF> = <Ctrl-L> = ASCII 12
          Clear  the  screen,  home  the  cursor.  Note that the screen is
          filled with the current display color.

   <SI><bg><fg>, <SI> = <Ctrl-O> = ASCII 15
          Set  the  display  colors  to  the  specified   background   and
          foreground   colors,   where  <bg>  and  <fg>  are  hex  digits,
          corresponding to the standard PC display attributes:

          0 = black          8 = dark grey
          1 = dark blue      9 = bright blue
          2 = dark green     a = bright green
          3 = dark cyan      b = bright cyan
          4 = dark red       c = bright red
          5 = dark purple    d = bright purple
          6 = brown          e = yellow
          7 = light grey     f = white

          Picking a bright color (8-f) for the background results  in  the
          corresponding dark color (0-7), with the foreground flashing.

          colors are not visible over the serial console.

   <CAN>filename<newline>, <CAN> = <Ctrl-X> = ASCII 24
          If a VGA display is present, enter graphics mode and display the
          graphic included in the specified file.  The file format  is  an
          ad   hoc   format   called  LSS16;  the  included  Perl  program
          "ppmtolss16" can be used to produce  these  images.   This  Perl
          program also includes the file format specification.

          The  image  is  displayed  in  640x480  16-color  mode.  Once in
          graphics  mode,  the  display  attributes  (set  by  <SI>   code
          sequences)  work  slightly  differently: the background color is
          ignored, and the foreground colors are the 16  colors  specified
          in  the  image  file.  For that reason, ppmtolss16 allows you to
          specify that certain colors should be assigned to specific color

          Color  indicies  0  and  7, in particular, should be chosen with
          care: 0 is the background color, and 7 is the color used for the
          text printed by SYSLINUX itself.

   <EM>, <EM> = <Ctrl-U> = ASCII 25
          If we are currently in graphics mode, return to text mode.

   <DLE>..<ETB>, <Ctrl-P>..<Ctrl-W> = ASCII 16-23
          These codes can be used to select which modes to print a certain
          part of the message file in.  Each of these  control  characters
          select  a  specific  set of modes (text screen, graphics screen,
          serial port) for which the output is actually displayed:

          Character                       Text    Graph   Serial
          <DLE> = <Ctrl-P> = ASCII 16     No      No      No
          <DC1> = <Ctrl-Q> = ASCII 17     Yes     No      No
          <DC2> = <Ctrl-R> = ASCII 18     No      Yes     No
          <DC3> = <Ctrl-S> = ASCII 19     Yes     Yes     No
          <DC4> = <Ctrl-T> = ASCII 20     No      No      Yes
          <NAK> = <Ctrl-U> = ASCII 21     Yes     No      Yes
          <SYN> = <Ctrl-V> = ASCII 22     No      Yes     Yes
          <ETB> = <Ctrl-W> = ASCII 23     Yes     Yes     Yes

          For example:
          <DC1>Text mode<DC2>Graphics mode<DC4>Serial port<ETB>
           ... will actually print out which mode the console is in!

   <SUB> = <Ctrl-Z> = ASCII 26
          End of file (DOS convention).

   Other operating systems
   This version of syslinux supports  chain  loading  of  other  operating
   systems (such as MS-DOS and its derivatives, including Windows 95/98).

   Chain  loading requires the boot sector of the foreign operating system
   to be stored in a  file  in  the  root  directory  of  the  filesystem.
   Because  neither  Linux  kernels,  nor boot sector images have reliable
   magic numbers, syslinux will look at the file extension. The  following
   extensions are recognised:

   none or other    Linux kernel image
   BSS              Boot sector (DOS superblock will be patched in)
   BS               Boot sector

   For  filenames  given on the command line, syslinux will search for the
   file by adding extensions in  the  order  listed  above  if  the  plain
   filename  is  not  found.  Filenames in KERNEL statements must be fully

   Novice protection
   Syslinux will attempt to detect if the user is trying to boot on a  286
   or lower class machine, or a machine with less than 608K of low ("DOS")
   RAM (which means the Linux boot sequence cannot complete).   If  so,  a
   message  is  displayed and the boot sequence aborted.  Holding down the
   Ctrl key while booting disables this feature.

   The compile time and  date  of  a  specific  syslinux  version  can  be
   obtained  by  the  DOS command "type ldlinux.sys". This is also used as
   the signature for the LDLINUX.SYS  file,  which  must  match  the  boot

   Any file that syslinux uses can be marked hidden, system or readonly if
   so is convenient; syslinux ignores all file attributes.   The  SYSLINUX
   installed automatically sets the readonly attribute on LDLINUX.SYS.

   Bootable CD-ROMs
   SYSLINUX can be used to create bootdisk images for El Torito-compatible
   bootable CD-ROMs. However, it appears that many BIOSes are  very  buggy
   when  it  comes  to  booting CD-ROMs. Some users have reported that the
   following steps are helpful in making a CD-ROM that is bootable on  the
   largest possible number of machines:

   *      Use the -s (safe, slow and stupid) option to SYSLINUX

   *      Put  the  boot  image  as close to the beginning of the ISO 9660
          filesystem as possible.

   A CD-ROM is so much faster than a floppy that the -s  option  shouldn't
   matter from a speed perspective.

   Of  course,  you  probably  want  to  use  ISOLINUX  instead.   See the
   documentation file isolinux.doc.

   Booting from a FAT partition on a hard disk
   SYSLINUX can boot from a  FAT  filesystem  partition  on  a  hard  disk
   (including  FAT32).  The  installation  procedure  is  identical to the
   procedure for installing it on a floppy, and should work  under  either
   DOS  or  Linux. To boot from a partition, SYSLINUX needs to be launched
   from a Master Boot Record or another boot loader, just like DOS  itself
   would. A sample master boot sector (mbr.bin) is included with SYSLINUX.


   I  would  appreciate hearing of any problems you have with SYSLINUX.  I
   would also like  to  hear  from  you  if  you  have  successfully  used
   SYSLINUX, especially if you are using it for a distribution.

   If  you are reporting problems, please include all possible information
   about your system and your BIOS; the  vast  majority  of  all  problems
   reported  turn  out  to  be  BIOS  or hardware bugs, and I need as much
   information as possible in order to diagnose the problems.

   There is a mailing list for discussion among  SYSLINUX  users  and  for
   announcements  of  new  and  test  versions. To join, send a message to with the line:

   subscribe syslinux

   in   the   body   of   the   message.   The   submission   address   is


   lilo(8),, fdisk(8), mkfs(8), superformat(1).


   This  manual  page  is  a  modified  version  of  the original syslinux
   documentation by H. Peter Anvin <>. The  conversion  to  a
   manpage was made by Arthur Korn <>.


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