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



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

SYNOPSIS
       mkdosfs  [ -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-sectors ] [ -s  sectors-per-clus-
       ter ] [ -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  determiness  the  file
       system size.

OPTIONS
       -A     Use Atari variation of the MS-DOS filesystem. 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 filesystems are managed by raising the logi-
              cal sector size.  Under Atari format, an Atari-compatible serial
              number for the filesystem is generated, and a 12 bit FAT is used
              only for filesystems 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  sector
              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 and 16  bit,  whatever  fits  better  for  the
              filesystem  size.   32  bit  FAT  (FAT32 format) must (still) be
              selected explicitly if you want it.

       -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 filesystem; volume-id is
              a  32-bit  hexadecimal  number  (for  example,  2e24ec82).   The
              default  is  a  number  which depends on the filesystem creation
              time.

       -I     Normally you are not  allowed  to  use  any  'full'  fixed  disk
              devices.   mkdosfs will complain and tell you that it refuses to
              work.  This is different  when  usind  MO  disks.   One  doesn't
              always  need  partitions  on  MO  disks.   The  filesytem 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
              filesystem without having properly installed an  operating  sys-
              tem.  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 filesystem.  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 sectos. With FAT32 format at least
              2  reserved sectors are needed, the default is 32. Otherwise 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 bootable filesystems. This isn't as easy as you
       might think at first glance for various reasons and has been  discussed
       a lot already.  mkdosfs simply will not support it ;)

AUTHOR
       Dave  Hudson  -  <daveAThumbug.uk>;  modified  by  Peter  Anvin
       <hpaATyggdrasil.com>.   Fixes   and    additions    by    Roman    Hodek
       <romanAThodek.net> for Debian/GNU Linux.

ACKNOWLEDGEMENTS
       mkdosfs  is  based  on  code  from  mke2fs  (written  by  Remy  Card  -
       <cardATmasi.fr>) which is itself based on  mkfs  (written  by  Linus
       Torvalds - <torvaldsATcs.fi>).

SEE ALSO
       dosfsck(8), mkfs(8)



Version 2.x                       5 May 1995                        MKDOSFS(8)