NEWFS_MSDOS(8)   BSD System Manager's Manual (INtime Distributed RTOS only).

Name

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

Command line

newfs_msdos | fmtfat [-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 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 fmtfat utility is the same as newfs_msdos with an 8.3 filename. 

Options

-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...) format.

-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 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.

Notes

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 {
    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

History

The newfs_msdos utility first appeared in FreeBSD 3.0.

Authors

Robert Nordier <rnordier@FreeBSD.org>