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


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


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]


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 follows: -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.


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 */ };


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


The newfs_msdos utility exits 0 on success, and >0 if an error occurs.


Create a file system, using default parameters, on /dev/da0s1: newfs_msdos /dev/da0s1 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 <rnordier@FreeBSD.org> DragonFly 5.7-DEVELOPMENT September 9, 2019 DragonFly 5.7-DEVELOPMENT

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