NEWFS_MSDOS(8)		  BSD System Manager's Manual		NEWFS_MSDOS(8)

NAME
     newfs_msdos — construct a new MS-DOS (FAT) file system

SYNOPSIS
     newfs_msdos [-N] [-@ offset] [-B boot] [-C create-size] [-F FAT-type]
		 [-I VolumeId] [-L label] [-O OEM] [-S sector-size]
		 [-a FAT-size] [-b block-size] [-c cluster-size] [-e DirEnts]
		 [-f format] [-h heads] [-i info] [-k backup] [-m media]
		 [-n FATs] [-o hidden] [-r reserved] [-s total]
		 [-u track-size] special [disktype]

DESCRIPTION
     The newfs_msdos utility creates a FAT12, FAT16, or FAT32 file system on
     device or file named special, using disktab(5) entry disktype to deter‐
     mine geometry, if required.

     If special does not contain a / and -C is not used, it is assumed to be a
     device name and /dev/ is prepended to the name to construct the actual
     device name.  To work a file in the current directory use ./filename

     The options are as follow:

     -N      Do not create a file system: just print out parameters.

     -@ offset
	     Build the filesystem at the specified offset in bytes in the
	     device or file.  A suffix s, k, m, g (lower or upper case)
	     appended to the offset specifies that the number is in sectors,
	     kilobytes, megabytes or gigabytes, respectively.

     -B boot
	     Get bootstrap from file.

     -C create-size
	     Create the image file with the specified size.  A suffix charac‐
	     ter appended to the size is interpreted as for the -@ option.
	     The file is created by truncating any existing file with the same
	     name and resizing it to the requested size.  If the file system
	     supports sparse files, the space occupied on disk may be smaller
	     than the size specified as parameter.

     -F FAT-type
	     FAT type (one of 12, 16, or 32).

     -I VolumeID
	     Volume ID, a 32 bit number in decimal or hexadecimal (0x...) for‐
	     mat.

     -L label
	     Volume label (up to 11 characters).  The label should consist of
	     only those characters permitted in regular DOS (8+3) filenames.

     -O OEM  OEM string (up to 8 characters).  The default is "BSD4.4  ".

     -S sector-size
	     Number of bytes per sector.  Acceptable values are powers of 2 in
	     the range 512 through 32768, inclusive.

     -a FAT-size
	     Number of sectors per FAT.

     -b block-size
	     File system block size (bytes per cluster).  This should resolve
	     to an acceptable number of sectors per cluster (see below).

     -c cluster-size
	     Sectors per cluster.  Acceptable values are powers of 2 in the
	     range 1 through 128.  If the block or cluster size are not speci‐
	     fied, the code uses a cluster between 512 bytes and 32K depending
	     on the filesystem size.

     -e DirEnts
	     Number of root directory entries (FAT12 and FAT16 only).

     -f format
	     Specify a standard (floppy disk) format.  The standard formats
	     are (capacities in kilobytes): 160, 180, 320, 360, 640, 720,
	     1200, 1232, 1440, 2880.

     -h heads
	     Number of drive heads.

     -i info
	     Location of the file system info sector (FAT32 only).  A value of
	     0xffff signifies no info sector.

     -k backup
	     Location of the backup boot sector (FAT32 only).  A value of
	     0xffff signifies no backup sector.

     -m media
	     Media descriptor (acceptable range 0xf0 to 0xff).

     -n FATs
	     Number of FATs.  Acceptable values are 1 to 16 inclusive.	The
	     default is 2.

     -o hidden
	     Number of hidden sectors.

     -r reserved
	     Number of reserved sectors.

     -s total
	     File system size.

     -u track-size
	     Number of sectors per track.

NOTES
     If some parameters (e.g. size, number of sectors, etc.) are not specified
     through options or disktype, the program tries to generate them automati‐
     cally.  In particular, the size is determined as the device or file size
     minus the offset specified with the -@ option.  When the geometry is not
     available, it is assumed to be 63 sectors, 255 heads.  The size is then
     rounded to become a multiple of the track size and avoid complaints by
     some filesystem code.

     FAT file system parameters occupy a "Boot Sector BPB (BIOS Parameter
     Block)" in the first of the "reserved" sectors which precede the actual
     file system.  For reference purposes, this structure is presented below.

     struct bsbpb {
	 uint16_t    bpbBytesPerSec;	     /* [-S] bytes per sector */
	 uint8_t     bpbSecPerClust;	     /* [-c] sectors per cluster */
	 uint16_t    bpbResSectors;	     /* [-r] reserved sectors */
	 uint8_t     bpbFATs;		     /* [-n] number of FATs */
	 uint16_t    bpbRootDirEnts;	     /* [-e] root directory entries */
	 uint16_t    bpbSectors;	     /* [-s] total sectors */
	 uint8_t     bpbMedia;		     /* [-m] media descriptor */
	 uint16_t    bpbFATsecs;	     /* [-a] sectors per FAT */
	 uint16_t    bpbSecPerTrack;	     /* [-u] sectors per track */
	 uint16_t    bpbHeads;		     /* [-h] drive heads */
	 uint32_t    bpbHiddenSecs;	     /* [-o] hidden sectors */
	 uint32_t    bpbHugeSectors;	     /* [-s] big total sectors */
     };
     /* FAT32 extensions */
     struct bsxbpb {
	 uint32_t    bpbBigFATsecs;	     /* [-a] big sectors per FAT */
	 uint16_t    bpbExtFlags;	     /* control flags */
	 uint16_t    bpbFSVers; 	     /* file system version */
	 uint32_t    bpbRootClust;	     /* root directory start cluster */
	 uint16_t    bpbFSInfo; 	     /* [-i] file system info sector */
	 uint16_t    bpbBackup; 	     /* [-k] backup boot sector */
     };

LIMITATION
     The maximum file size is 4GB, even if the file system itself is bigger.

EXIT STATUS
     Exit status is 0 on success and 1 on error.

EXAMPLES
     Create a file system, using default parameters, on /dev/ada0s1:

	   newfs_msdos /dev/ada0s1

     Create a standard 1.44M file system, with volume label foo, on /dev/fd0:

	   newfs_msdos -f 1440 -L foo fd0

     Create a 30MB image file, with the FAT partition starting 63 sectors
     within the image file:

	   newfs_msdos -C 30M -@63s ./somefile

SEE ALSO
     gpart(8), newfs(8)

HISTORY
     The newfs_msdos utility first appeared in FreeBSD 3.0.

AUTHORS
     Robert Nordier ⟨rnordier@FreeBSD.org⟩.

BSD				 April 9, 2015				   BSD