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

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

newfs_msdos [-N] [-B boot] [-F FAT-type] [-I volid] [-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] [-v volume-name] special [disktype]

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 options are as follows:

Don't create a file system: just print out parameters.
boot
Get bootstrap from file.
FAT-type
FAT type (one of 12, 16, or 32).
volid
Volume ID.
OEM
OEM string (up to 8 characters). The default is "BSD 4.4" (with two spaces).
sector-size
Number of bytes per sector. Acceptable values are powers of 2 in the range 128 through 32768.
FAT-size
Number of sectors per FAT.
block-size
File system block size (bytes per cluster). This should resolve to an acceptable number of sectors per cluster (see below).
cluster-size
Sectors per cluster. Acceptable values are powers of 2 in the range 1 through 128.
dirents
Number of root directory entries (FAT12 and FAT16 only).
format
Specify a standard (floppy disk) format. The eight standard formats are (capacities in kilobytes): 160, 180, 320, 360, 640, 720, 1200, 1232, 1440, 2880.
heads
Number of drive heads.
info
Location of the file system info sector (FAT32 only). A value of 0xffff signifies no info sector.
backup
Location of the backup boot sector (FAT32 only). A value of 0xffff signifies no backup sector.
media
Media descriptor (acceptable range 0xf0 to 0xff).
FATs
Number of FATs. Acceptable values are 1 to 16 inclusive. The default is 2.
hidden
Number of hidden sectors.
reserved
Number of reserved sectors.
total
File system size, in sectors.
track-size
Number of sectors per track.
volume-name
Volume name (filesystem name), up to 11 characters. The name should consist of only those characters permitted in regular DOS (8+3) filenames.

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 */
};

newfs_msdos /dev/disk0s1

Create a file system, using default parameters, on /dev/disk0s1.

newfs_msdos -f 1440 -v foo fd0
Create a standard 1.44M file system, with volume name "foo", on /dev/fd0.

fdisk(8), mount(8)

Exit status is 0 on success and 1 on error.

The newfs_msdos command appeared in FreeBSD 3.0.

Robert Nordier ⟨rnordier@FreeBSD.org⟩.

July 6, 1998 macOS 15.6