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SYSLINUX(1)                                                        SYSLINUX(1)

       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-pur-
       pose 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 booting.

       -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 com-
              pletely, 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 "bau-
              drate" 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 configura-
              tion 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 con-
              tains a Unicode table it is ignored.  This only works on EGA and VGA cards; hopefully it should do noth-
              ing on others.

       kbdmap keymap
              Install  a simple keyboard map. The keyboard remapper used is very simplistic (it simply remaps the key-
              codes 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 ignored.

       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:" prompt.

       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 options.)

              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 ver-
              sions, 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 indicies.

              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  num-
       bers, 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 qualified.

   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 sector

       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 <>.

SYSLINUX                         19 July 2010                      SYSLINUX(1)