mkdosfs

MKFS.FAT(8)                 System Manager's Manual                MKFS.FAT(8)

NAME
       mkfs.fat - create an MS-DOS filesystem under Linux

SYNOPSIS
       mkfs.fat [OPTIONS] DEVICE [BLOCK-COUNT]

DESCRIPTION
       mkfs.fat is used to create an MS-DOS filesystem under Linux on a device
       (usually a disk partition).  DEVICE is the special  file  corresponding
       to the device (e.g. /dev/sdXX).  BLOCK-COUNT is the number of blocks on
       the device.  If omitted, mkfs.fat automatically determines the filesys-
       tem size.

OPTIONS
       -a  Normally,  for any filesystem except very small ones, mkfs.fat 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 ex-
           pense of a significant performance degradation on RAIDs, flash  me-
           dia or large-sector hard disks.

        -A Use  Atari  variation of the MS-DOS filesystem.  This is default if
           mkfs.fat is run on an Atari, then this option turns off Atari  for-
           mat.   There  are  some differences when using Atari format: If not
           directed otherwise by the user, mkfs.fat 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 logical sector size.
           Under Atari format,  an  Atari-compatible  serial  number  for  the
           filesystem is generated, and a 12 bit FAT is used only for filesys-
           tems 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 sectors.

       -c  Check the device for bad blocks before creating the filesystem.

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

       -D DRIVE-NUMBER
           Specify  the BIOS drive number to be stored in the FAT boot sector.
           This value is usually 0x80 for hard disks and 0x00 for  floppy  de-
           vices or partitions to be used for floppy emulation.

       -f NUMBER-OF-FATS
           Specify  the  number  of  file allocation tables in the filesystem.
           The default is 2.

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

       -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  It  is  typical for fixed disk devices to be partitioned so, by de-
           fault, you are not permitted to create a filesystem across the  en-
           tire  device.   mkfs.fat will complain and tell you that it refuses
           to work.  This is different when using MO disks.  One  doesn't  al-
           ways  need  partitions on MO disks.  The filesystem can go directly
           to the whole disk.  Under other OSes this is known as  the  'super-
           floppy' format.  This switch will force mkfs.fat 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  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.

       -M FAT-MEDIA-TYPE
           Specify the media type to be stored in the FAT boot  sector.   This
           value  is  usually  0xF8 for hard disks and is 0xF0 or a value from
           0xF9 to 0xFF for floppies or partitions to be used for floppy  emu-
           lation.

       -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 sectors.  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.  Values larger than 4096 are not  conforming
           to the FAT file system specification and may not work everywhere.

       -v  Verbose execution.

       --invariant
           Use  constants  for  normally randomly generated or time based data
           such as volume ID and creation time.  Multiple runs of mkfs.fat  on
           the  same  device  create  identical results with this option.  Its
           main purpose is testing mkfs.fat.

       --help
           Display option summary and exit.

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

SEE ALSO
       fatlabel(8)
       fsck.fat(8)

HOMEPAGE
       The home  for  the  dosfstools  project  is  its  GitHub  project  page
       <https://github.com/dosfstools/dosfstools>.

AUTHORS
       dosfstools  were  written  by  Werner  Almesberger <werner.almesberger@
       lrc.di.epfl.ch>, Roman Hodek  <Roman.Hodek@informatik.uni-erlangen.de>,
       and others.  The current maintainer is Andreas Bombe <aeb@debian.org>.

dosfstools 4.1                    2016-01-25                       MKFS.FAT(8)