Provided by: dosfstools_4.2-1build1_amd64 bug

NAME

       mkfs.fat - create an MS-DOS FAT filesystem

SYNOPSIS

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

DESCRIPTION

       mkfs.fat  is  used  to create a FAT filesystem on a device or in an image file.  DEVICE is
       the special file corresponding to the device (e.g. /dev/sdXX) or  the  image  file  (which
       does  not need to exist when the option -C is given).  BLOCK-COUNT is the number of blocks
       on the device and size of one block is always 1024 bytes, independently of the sector size
       or  the  cluster size.  Therefore BLOCK-COUNT specifies size of filesystem in KiB unit and
       not in the number of sectors (like for all other mkfs.fat options).  If omitted,  mkfs.fat
       automatically chooses a filesystem size to fill the available space.

       Two  different variants of the FAT filesystem are supported.  Standard is the FAT12, FAT16
       and FAT32 filesystems as defined by Microsoft and widely used on hard disks and  removable
       media  like  USB sticks and SD cards.  The other is the legacy Atari variant used on Atari
       ST.

       In Atari mode, 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.   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.

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 expense
           of  a  significant  performance degradation on RAIDs, flash media or large-sector hard
           disks.

       -A  Select using the Atari variation of the FAT filesystem if that isn't  active  already,
           otherwise  select standard FAT filesystem.  This is selected by default if mkfs.fat is
           run on 68k Atari Linux.

       -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.  If there is a free space available
           after the backup boot sector then backup of the FAT32 info sector  is  put  after  the
           backup  boot  sector,  usually  at  sector  7.  The backup must be within the range of
           reserved sectors.  Value 0 completely disables creating of backup boot and info  FAT32
           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 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  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
           correct 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.  For hard disks and
           removable medias it is usually 0x80–0xFF (0x80 is first hard disk C:, 0x81  is  second
           hard  disk  D:, ...), for floppy devices or partitions to be used for floppy emulation
           it is 0x00–0x7F (0x00 is first floppy A:, 0x01 is second floppy B:).

       -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.

       -g HEADS/SECTORS-PER-TRACK
           Specify HEADS and SECTORS-PER-TRACK numbers which represents disk geometry of  DEVICE.
           Both  numbers  are  stored into the FAT boot sector.  Number SECTORS-PER-TRACK is used
           also for aligning the total count of FAT sectors.  By default disk  geometry  is  read
           from  DEVICE  itself.   If  it  is  not  available  then  LBA-Assist  Translation  and
           translation table from the SD Card Part 2 File System  Specification  based  on  total
           number of disk sectors is used.

       -h NUMBER-OF-HIDDEN-SECTORS
           Specify the number of so-called hidden sectors, as stored in the FAT boot sector: this
           number represents the beginning sector of the partition containing  the  file  system.
           Normally  this  is  an offset (in sectors) relative to the start of the disk, although
           for MBR logical volumes contained in an extended partition of  type  0x05  (a  non-LBA
           extended  partition),  a  quirk  in the MS-DOS implementation of FAT requires it to be
           relative to the partition's immediate containing Extended Boot Record.  Boot code  and
           other  software  handling  FAT  volumes  may  also  rely  on  this  field being set up
           correctly; most modern FAT implementations will ignore it.  By default, if the  DEVICE
           is  a  partition  block  device,  mkfs.fat  uses the partition offset relative to disk
           start.  Otherwise, mkfs.fat assumes zero.  Use this option to override this behaviour.

       -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  Ignore and disable safety checks.  By default mkfs.fat refuses to create a  filesystem
           on  a  device with partitions or virtual mapping.  mkfs.fat 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 filesystem can go directly to the whole disk.  Under
           other OSes this is known as the superfloppy 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 emulation.

       --mbr[=y|yes|n|no|a|auto]
           Fill  (fake)  MBR  table  with  disk  signature one partition which starts at sector 0
           (includes MBR itself) and spans whole  disk  device.   It  is  needed  only  for  non-
           removable  disks  used  on  Microsoft  Windows  systems and only when formatting whole
           unpartitioned disk.  Location of the disk signature and partition table overlaps  with
           the end of the first FAT sector (boot code location), therefore there is no additional
           space usage.  Default is auto mode in which mkfs.fat  put  MBR  table  only  for  non-
           removable disks when formatting whole unpartitioned disk.

       -n VOLUME-NAME
           Sets  the  volume  name  (label)  of  the filesystem.  The volume name can be up to 11
           characters long.  Supplying an empty string, a string consisting only of  white  space
           or  the  string  "NO  NAME"  as  VOLUME-NAME  has the same effect as not giving the -n
           option.  The default is no label.

       --codepage=PAGE
           Use DOS codepage PAGE to encode label.  By default codepage 850 is used.

       -r ROOT-DIR-ENTRIES
           Select the minimal number of entries available in the root directory.  The default  is
           112  or 224 for floppies and 512 for hard disks.  Note that this is minimal number and
           it may be increased by mkfs.fat due to alignment of  structures.   See  also  mkfs.fat
           option -a.

       -R NUMBER-OF-RESERVED-SECTORS
           Select  the minimal 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).   Note that this is minimal number and it may be increased by mkfs.fat due to
           alignment of structures.  See also mkfs.fat option -a.

       -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.

       --offset SECTOR
           Write the filesystem at a specific sector into the device file.  This  is  useful  for
           creating  a  filesystem  in  a  partitioned disk image without having to set up a loop
           device.

       --variant TYPE
           Create a filesystem of variant TYPE.  Acceptable values are standard and atari (in any
           combination of upper/lower case).  See above under DESCRIPTION for the differences.

       --help
           Display option summary and exit.

       --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.

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 discussed 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.   Current  maintainers  are
       Andreas Bombe ⟨aeb@debian.org⟩ and Pali Rohár ⟨pali.rohar@gmail.com⟩.