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 filesystem 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 expense
           of a significant performance degradation on RAIDs, flash media  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 format.  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 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 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.   This  value  is
           usually  0x80  for hard disks and 0x00 for floppy devices 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  default,  you  are  not
           permitted to create a filesystem across the entire device.  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.

       -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.

       -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 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.   The  current  maintainer  is
       Andreas Bombe ⟨aeb@debian.org⟩.