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

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

     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]

     The newfs_msdos utility creates a FAT12, FAT16, or FAT32 file system on
     device or file named special, using disktab(5) entry disktype to
     determine 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
             character 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...)

     -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 "BSD  4.4".

     -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
             specified, 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.

     If some parameters (e.g. size, number of sectors, etc.) are not specified
     through options or disktype, the program tries to generate them
     automatically.  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 {
         u_int16_t   bpbBytesPerSec;         /* [-S] bytes per sector */
         u_int8_t    bpbSecPerClust;         /* [-c] sectors per cluster */
         u_int16_t   bpbResSectors;          /* [-r] reserved sectors */
         u_int8_t    bpbFATs;                /* [-n] number of FATs */
         u_int16_t   bpbRootDirEnts;         /* [-e] root directory entries */
         u_int16_t   bpbSectors;             /* [-s] total sectors */
         u_int8_t    bpbMedia;               /* [-m] media descriptor */
         u_int16_t   bpbFATsecs;             /* [-a] sectors per FAT */
         u_int16_t   bpbSecPerTrack;         /* [-u] sectors per track */
         u_int16_t   bpbHeads;               /* [-h] drive heads */
         u_int32_t   bpbHiddenSecs;          /* [-o] hidden sectors */
         u_int32_t   bpbHugeSectors;         /* [-s] big total sectors */
     /* FAT32 extensions */
     struct bsxbpb {
         u_int32_t   bpbBigFATsecs;          /* [-a] big sectors per FAT */
         u_int16_t   bpbExtFlags;            /* control flags */
         u_int16_t   bpbFSVers;              /* file system version */
         u_int32_t   bpbRootClust;           /* root directory start cluster */
         u_int16_t   bpbFSInfo;              /* [-i] file system info sector */
         u_int16_t   bpbBackup;              /* [-k] backup boot sector */

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

     Exit status is 0 on success and 1 on error.

     Create a file system, using default parameters, on /dev/ad0s1:

           newfs_msdos /dev/ad0s1

     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

     disktab(5), disklabel(8), fdisk(8), newfs(8)

     The newfs_msdos utility first appeared in FreeBSD 3.0.

     Robert Nordier <>.

FreeBSD 11.0-PRERELEASE          July 25, 2010         FreeBSD 11.0-PRERELEASE


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