MKDOSFS(8)		    System Manager's Manual		    MKDOSFS(8)



NAME
       mkdosfs - create an MS-DOS file system under Linux

SYNOPSIS
       mkdosfs|mkfs.msdos|mkfs.vfat [ -a ] [ -A ] [ -b sector-of-backup ] [ -c
       ] [ -l filename ] [ -C ] [ -f number-of-FATs ] [ -F  FAT-size  ]	 [  -h
       number-of-hidden-sectors	 ] [ -i volume-id ] [ -I ] [ -m message-file ]
       [ -n volume-name ] [ -r root-dir-entries ] [ -R number-of-reserved-sec-
       tors  ]	[  -s  sectors-per-cluster ] [ -S logical-sector-size ] [ -v ]
       device [ block-count ]

DESCRIPTION
       mkdosfs is used to create an MS-DOS file system under Linux on a device
       (usually	 a  disk partition).  device is the special file corresponding
       to the device (e.g /dev/hdXX).  block-count is the number of blocks  on
       the device.  If omitted, mkdosfs automatically determines the file sys-
       tem size.

OPTIONS
       -a     Normally, for any filesystem except  very	 small	ones,  mkdosfs
	      will align all the data structures to cluster size, to make sure
	      that as long as the partition is properly aligned, so  will  all
	      the  data	 structures  in	 the filesystem.  This option disables
	      alignment; this may provide a handful of additional clusters  of
	      storage  at the expense of a significant performance degradation
	      on RAIDs, flash media or large-sector hard disks.

       -A     Use Atari variation of the MS-DOS file system. This  is  default
	      if  mkdosfs is run on an Atari, then this option turns off Atari
	      format. There are some differences when using Atari  format:  If
	      not  directed  otherwise	by the user, mkdosfs will always use 2
	      sectors per cluster, since GEMDOS doesn't like other values very
	      much.   It  will	also obey the maximum number of sectors GEMDOS
	      can handle.  Larger file systems are managed by raising the log-
	      ical  sector  size.   Under  Atari  format,  an Atari-compatible
	      serial number for the file system is generated, and a 12 bit FAT
	      is  used only for file systems that have one of the usual floppy
	      sizes (720k, 1.2M, 1.44M, 2.88M), a 16 bit FAT  otherwise.  This
	      can be overridden with the -F option. Some PC-specific boot sec-
	      tor fields aren't written, and a boot  message  (option  -m)  is
	      ignored.

       -b sector-of-backup
	      Selects  the  location  of  the  backup  boot  sector for FAT32.
	      Default depends on number of reserved sectors,  but  usually  is
	      sector  6.  The backup must be within the range of reserved sec-
	      tors.

       -c     Check the device for bad blocks before creating the file system.

       -C     Create the file given as device on the command line,  and	 write
	      the  to-be-created file system to it. This can be used to create
	      the new file system in a file instead of on a real  device,  and
	      to  avoid	 using	dd  in advance to create a file of appropriate
	      size. With this option, the block-count must be  given,  because
	      otherwise	 the  intended	size  of  the  file system wouldn't be
	      known. The file created is a sparse file,	 which	actually  only
	      contains the meta-data areas (boot sector, FATs, and root direc-
	      tory). The data portions won't be stored on the  disk,  but  the
	      file nevertheless will have the correct size. The resulting file
	      can be copied later to a floppy disk or other device, or mounted
	      through a loop device.

       -f number-of-FATs
	      Specify the number of file allocation tables in the file system.
	      The default is 2.	 Currently the Linux MS-DOS file  system  does
	      not support more than 2 FATs.

       -F FAT-size
	      Specifies	 the type of file allocation tables used (12, 16 or 32
	      bit).  If	 nothing  is  specified,  mkdosfs  will	 automatically
	      select  between  12, 16 and 32 bit, whatever fits better for the
	      file system size.

       -h number-of-hidden-sectors
	      Select the number of hidden sectors in  the  volume.  Apparently
	      some  digital cameras get indigestion if you feed them a CF card
	      without such hidden sectors, this option allows you  to  satisfy
	      them. Assumes '0' if no value is given on the command line.

       -i  volume-id
	      Sets  the	 volume ID of the newly created file system; volume-id
	      is a 32-bit hexadecimal number  (for  example,  2e24ec82).   The
	      default  is  a  number which depends on the file system creation
	      time.

       -I     It is typical for fixed disk devices to be  partitioned  so,  by
	      default, you are not permitted to create a filesystem across the
	      entire device.  mkdosfs will  complain  and  tell	 you  that  it
	      refuses  to  work.   This is different when using MO disks.  One
	      doesn't always need partitions on MO disks.  The file system can
	      go  directly  to the whole disk.	Under other OSes this is known
	      as the 'superfloppy' format.

	      This switch will force mkdosfs to work properly.

       -l filename
	      Read the bad blocks list from filename.

       -m message-file
	      Sets the message the user receives on attempts to boot this file
	      system  without  having  properly installed an operating system.
	      The message file must not exceed 418 bytes once line feeds  have
	      been  converted  to  carriage return-line feed combinations, and
	      tabs have been expanded.	If the filename is a hyphen  (-),  the
	      text is taken from standard input.

       -n volume-name
	      Sets  the	 volume	 name  (label) of the file system.  The volume
	      name can be up to 11 characters long.  The default is no label.

       -r root-dir-entries
	      Select the number of entries available in	 the  root  directory.
	      The default is 112 or 224 for floppies and 512 for hard disks.

       -R number-of-reserved-sectors
	      Select  the  number  of  reserved	 sectors. With FAT32 format at
	      least 2 reserved sectors are needed, the default is  32.	Other-
	      wise the default is 1 (only the boot sector).

       -s sectors-per-cluster
	      Specify the number of disk sectors per cluster.  Must be a power
	      of 2, i.e. 1, 2, 4, 8, ... 128.

       -S logical-sector-size
	      Specify the number of bytes per logical sector.  Must be a power
	      of  2  and  greater  than or equal to 512, i.e. 512, 1024, 2048,
	      4096, 8192, 16384, or 32768.

       -v     Verbose execution.

BUGS
       mkdosfs can not create boot-able file systems. This isn't  as  easy  as
       you  might  think at first glance for various reasons and has been dis-
       cussed a lot already.  mkdosfs simply will not support it ;)

AUTHOR
       Dave  Hudson  -	<dave@humbug.demon.co.uk>;  modified  by  Peter	 Anvin
       <hpa@yggdrasil.com>.    Fixes	and    additions    by	 Roman	 Hodek
       <roman@hodek.net> for Debian/GNU Linux.

ACKNOWLEDGMENTS
       mkdosfs	is  based  on  code  from  mke2fs  (written  by	 Remy  Card  -
       <card@masi.ibp.fr>)  which  is  itself  based on mkfs (written by Linus
       Torvalds - <torvalds@cs.helsinki.fi>).

SEE ALSO
       dosfsck(8), dosfslabel(8), mkfs(8)



Version 2.x			  5 May 1995			    MKDOSFS(8)