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33 .Nd construct a new MS-DOS (FAT) file system
40 .Op Fl C Ar create-size
45 .Op Fl S Ar sector-size
48 .Op Fl b Ar block-size
49 .Op Fl c Ar cluster-size
60 .Op Fl u Ar track-size
66 utility creates a FAT12, FAT16, or FAT32 file system on device or file named
72 to determine geometry, if required.
80 is not used, it is assumed to be a device name and
82 is prepended to the name to construct the actual device name.
83 To work a file in the current directory use
86 The options are as follow:
87 .Bl -tag -width indent
89 Do not create a file system: just print out parameters.
91 Build the filesystem at the specified offset in bytes in the device or file.
92 A suffix s, k, m, g (lower or upper case)
93 appended to the offset specifies that the
94 number is in sectors, kilobytes, megabytes or gigabytes, respectively.
96 Attempt to cluster align root directory, useful for SD card.
98 Get bootstrap from file.
99 .It Fl C Ar create-size
100 Create the image file with the specified size.
101 A suffix character appended to the size is interpreted as for the
104 The file is created by truncating any existing file with the same name and
105 resizing it to the requested size.
106 If the file system supports sparse files, the space occupied on disk may be
107 smaller than the size specified as parameter.
109 FAT type (one of 12, 16, or 32).
111 Volume ID, a 32 bit number in decimal or hexadecimal (0x...) format.
113 Volume label (up to 11 characters).
114 The label should consist of
115 only those characters permitted in regular DOS (8+3) filenames.
117 OEM string (up to 8 characters).
120 .It Fl S Ar sector-size
121 Number of bytes per sector.
122 Acceptable values are powers of 2
123 in the range 512 through 32768, inclusive.
124 .It Fl T Ar timestamp
125 Create the filesystem as though the current time is
127 The default filesystem volume ID is derived from the time.
129 can be a pathname (where the timestamp is derived from
130 that file) or an integer value interpreted
131 as the number of seconds since the Epoch.
133 Number of sectors per FAT.
134 .It Fl b Ar block-size
135 File system block size (bytes per cluster).
136 This should resolve to an
137 acceptable number of sectors per cluster (see below).
138 .It Fl c Ar cluster-size
140 Acceptable values are powers of 2 in the range
142 If the block or cluster size are not specified, the code
143 uses a cluster between 512 bytes and 32K depending on
146 Number of root directory entries (FAT12 and FAT16 only).
148 Specify a standard (floppy disk) format.
150 are (capacities in kilobytes): 160, 180, 320, 360, 640, 720, 1200,
153 Number of drive heads.
155 Location of the file system info sector (FAT32 only).
156 A value of 0xffff signifies no info sector.
158 Location of the backup boot sector (FAT32 only).
160 of 0xffff signifies no backup sector.
162 Media descriptor (acceptable range 0xf0 to 0xff).
165 Acceptable values are 1 to 16 inclusive.
169 Number of hidden sectors.
171 Number of reserved sectors.
174 .It Fl u Ar track-size
175 Number of sectors per track.
178 If some parameters (e.g., size, number of sectors, etc.) are not specified
179 through options or disktype, the program tries to generate them automatically.
180 In particular, the size is determined as the device or file size minus the
181 offset specified with the
184 When the geometry is not available, it is assumed to be 63 sectors, 255 heads.
185 The size is then rounded to become a multiple of the track size and avoid
186 complaints by some filesystem code.
188 FAT file system parameters occupy a "Boot Sector BPB (BIOS Parameter
189 Block)" in the first of the "reserved" sectors which precede the actual
191 For reference purposes, this structure is presented
195 uint16_t bpbBytesPerSec; /* [-S] bytes per sector */
196 uint8_t bpbSecPerClust; /* [-c] sectors per cluster */
197 uint16_t bpbResSectors; /* [-r] reserved sectors */
198 uint8_t bpbFATs; /* [-n] number of FATs */
199 uint16_t bpbRootDirEnts; /* [-e] root directory entries */
200 uint16_t bpbSectors; /* [-s] total sectors */
201 uint8_t bpbMedia; /* [-m] media descriptor */
202 uint16_t bpbFATsecs; /* [-a] sectors per FAT */
203 uint16_t bpbSecPerTrack; /* [-u] sectors per track */
204 uint16_t bpbHeads; /* [-h] drive heads */
205 uint32_t bpbHiddenSecs; /* [-o] hidden sectors */
206 uint32_t bpbHugeSectors; /* [-s] big total sectors */
208 /* FAT32 extensions */
210 uint32_t bpbBigFATsecs; /* [-a] big sectors per FAT */
211 uint16_t bpbExtFlags; /* control flags */
212 uint16_t bpbFSVers; /* file system version */
213 uint32_t bpbRootClust; /* root directory start cluster */
214 uint16_t bpbFSInfo; /* [-i] file system info sector */
215 uint16_t bpbBackup; /* [-k] backup boot sector */
219 The maximum file size is 4GB, even if the file system itself is bigger.
221 Exit status is 0 on success and 1 on error.
223 Create a file system, using default parameters, on
225 .Bd -literal -offset indent
226 newfs_msdos /dev/ada0s1
229 Create a standard 1.44M file system, with volume label
233 .Bd -literal -offset indent
234 newfs_msdos -f 1440 -L foo fd0
237 Create a 30MB image file, with the FAT partition starting
238 63 sectors within the image file:
239 .Bd -literal -offset indent
240 newfs_msdos -C 30M -@63s ./somefile
248 utility first appeared in
251 .An Robert Nordier Aq Mt rnordier@FreeBSD.org