NEWFS_MSDOS(8) FreeBSD System Manager's Manual NEWFS_MSDOS(8)
NAME
newfs_msdos - construct a new MS-DOS (FAT) file system
SYNOPSIS
newfs_msdos [-N] [-@ offset] [-A] [-B boot] [-C create-size]
[-F FAT-type] [-I VolumeID] [-L label] [-O OEM]
[-S sector-size] [-T timestamp] [-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 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.
-A Attempt to cluster align root directory, useful for SD card.
-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.
-T timestamp
Create the filesystem as though the current time is timestamp.
The default filesystem volume ID is derived from the time.
timestamp can be a pathname (where the timestamp is derived from
that file) or an integer value interpreted as the number of
seconds since the Epoch.
-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
SEE ALSO
gpart(8), newfs(8)
HISTORY
The newfs_msdos utility first appeared in FreeBSD 3.0.
AUTHORS
Robert Nordier <rnordier@FreeBSD.org>
FreeBSD 13.1-RELEASE-p6 June 14, 2018 FreeBSD 13.1-RELEASE-p6
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