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

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

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

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

     The special file should be a raw device, for example /dev/rsd0i; if a
     relative path like sd0i is specified, the corresponding raw device is
     used.

     The options are as follows:

     -a FAT-size
             Number of sectors per FAT.

     -B boot
             Get bootstrap from file.

     -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.

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

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

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

     -h heads
             Number of drive heads.

     -I volid
             Volume ID.

     -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.

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

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

     -N      Don't create a file system: just print out parameters.

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

     -O OEM  OEM string (up to 8 characters).  The default is "BSD  4.4".

     -o hidden
             Number of hidden sectors.

     -r reserved
             Number of reserved sectors.

     -S sector-size
             Number of bytes per sector.  Acceptable values are powers of 2 in
             the range 128 through 32768.

     -s total
             File system size.

     -u track-size
             Number of sectors per track.

NOTES
     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       bps;            /* [-S] bytes per sector */
             u_int8_t        spc;            /* [-c] sectors per cluster */
             u_int16_t       res;            /* [-r] reserved sectors */
             u_int8_t        nft;            /* [-n] number of FATs */
             u_int16_t       rde;            /* [-e] root directory entries */
             u_int16_t       sec;            /* [-s] total sectors */
             u_int8_t        mid;            /* [-m] media descriptor */
             u_int16_t       spf;            /* [-a] sectors per FAT */
             u_int16_t       spt;            /* [-u] sectors per track */
             u_int16_t       hds;            /* [-h] drive heads */
             u_int32_t       hid;            /* [-o] hidden sectors */
             u_int32_t       bsec;           /* [-s] big total sectors */
     };

     /* FAT32 extensions */
     struct bsxbpb {
             u_int32_t       bspf;           /* [-a] big sectors per FAT */
             u_int16_t       xflg;           /* control flags */
             u_int16_t       vers;           /* file system version */
             u_int32_t       rdcl;           /* root directory start cluster */
             u_int16_t       infs;           /* [-i] file system info sector */
             u_int16_t       bkbs;           /* [-k] backup boot sector */
     };

EXAMPLES
     Create a file system, using default parameters, on /dev/rwd0i.
           newfs_msdos /dev/rwd0i

     Create a standard 1.44M file system, with volume label "foo", on
     /dev/rfd0c.
           newfs_msdos -f 1440 -L foo fd0c

DIAGNOSTICS
     Exit status is 0 on success and 1 on error.

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

HISTORY
     The newfs_msdos command first appeared in OpenBSD 2.1.

AUTHORS
     Robert Nordier <rnordier@FreeBSD.org>.

OpenBSD 4.7                      July 27, 2009                               3
