1MKDOSFS(8) System Manager's Manual MKDOSFS(8)
2
6 mkdosfs - create an MS-DOS file system under Linux
7
9 mkdosfs [ -A ] [ -b sector-of-backup ] [ -c ] [ -l filename ] [ -C ] [
10 -f number-of-FATs ] [ -F FAT-size ] [ -h number-of-hidden-sectors ] [
11 -i volume-id ] [ -I ] [ -m message-file ] [ -n volume-name ] [ -r root-
12 dir-entries ] [ -R number-of-reserved-sectors ] [ -s sectors-per-clus‐
13 ter ] [ -S logical-sector-size ] [ -v ] device [ block-count ]
14
16 mkdosfs is used to create an MS-DOS file system under Linux on a device
17 (usually a disk partition). device is the special file corresponding
18 to the device (e.g /dev/hdXX). block-count is the number of blocks on
19 the device. If omitted, mkdosfs automatically determiness the file
20 system size.
21
23 -A Use Atari variation of the MS-DOS filesystem. This is default if
24 mkdosfs is run on an Atari, then this option turns off Atari
25 format. There are some differences when using Atari format: If
26 not directed otherwise by the user, mkdosfs will always use 2
27 sectors per cluster, since GEMDOS doesn't like other values very
28 much. It will also obey the maximum number of sectors GEMDOS
29 can handle. Larger filesystems are managed by raising the logi‐
30 cal sector size. Under Atari format, an Atari-compatible serial
31 number for the filesystem is generated, and a 12 bit FAT is used
32 only for filesystems that have one of the usual floppy sizes
33 (720k, 1.2M, 1.44M, 2.88M), a 16 bit FAT otherwise. This can be
34 overridden with the -F option. Some PC-specific boot sector
35 fields aren't written, and a boot message (option -m) is
36 ignored.
37 -b sector-of-backup
39 Selects the location of the backup boot sector for FAT32.
40 Default depends on number of reserved sectors, but usually is
41 sector 6. The backup must be within the range of reserved sec‐
42 tors.
43 -c Check the device for bad blocks before creating the file system.
45 -C Create the file given as device on the command line, and write
47 the to-be-created file system to it. This can be used to create
48 the new file system in a file instead of on a real device, and
49 to avoid using dd in advance to create a file of appropriate
50 size. With this option, the block-count must be given, because
51 otherwise the intended size of the file system wouldn't be
52 known. The file created is a sparse file, which actually only
53 contains the meta-data areas (boot sector, FATs, and root direc‐
54 tory). The data portions won't be stored on the disk, but the
55 file nevertheless will have the correct size. The resulting file
56 can be copied later to a floppy disk or other device, or mounted
57 through a loop device.
58 -f number-of-FATs
60 Specify the number of file allocation tables in the file system.
61 The default is 2. Currently the Linux MS-DOS file system does
62 not support more than 2 FATs.
63 -F FAT-size
65 Specifies the type of file allocation tables used (12, 16 or 32
66 bit). If nothing is specified, mkdosfs will automatically
67 select between 12 and 16 bit, whatever fits better for the
68 filesystem size. 32 bit FAT (FAT32 format) must (still) be
69 selected explicitly if you want it.
70 -h number-of-hidden-sectors
72 Select the number of hidden sectors in the volume. Apparently
73 some digital cameras get indigestion if you feed them a CF card
74 without such hidden sectors, this option allows you to satisfy
75 them. Assumes ´0´ if no value is given on the command line.
76 -i volume-id
78 Sets the volume ID of the newly created filesystem; volume-id is
79 a 32-bit hexadecimal number (for example, 2e24ec82). The
80 default is a number which depends on the filesystem creation
81 time.
82 -I Normally you are not allowed to use any 'full' fixed disk
84 devices. mkdosfs will complain and tell you that it refuses to
85 work. This is different when usind MO disks. One doesn't
86 always need partitions on MO disks. The filesytem can go
87 directly to the whole disk. Under other OSes this is known as
88 the 'superfloppy' format.
89 This switch will force mkdosfs to work properly.
91 -l filename
93 Read the bad blocks list from filename.
94 -m message-file
96 Sets the message the user receives on attempts to boot this
97 filesystem without having properly installed an operating sys‐
98 tem. The message file must not exceed 418 bytes once line feeds
99 have been converted to carriage return-line feed combinations,
100 and tabs have been expanded. If the filename is a hyphen (-),
101 the text is taken from standard input.
102 -n volume-name
104 Sets the volume name (label) of the filesystem. The volume name
105 can be up to 11 characters long. The default is no label.
106 -r root-dir-entries
108 Select the number of entries available in the root directory.
109 The default is 112 or 224 for floppies and 512 for hard disks.
110 -R number-of-reserved-sectors
112 Select the number of reserved sectos. With FAT32 format at least
113 2 reserved sectors are needed, the default is 32. Otherwise the
114 default is 1 (only the boot sector).
115 -s sectors-per-cluster
117 Specify the number of disk sectors per cluster. Must be a power
118 of 2, i.e. 1, 2, 4, 8, ... 128.
119 -S logical-sector-size
121 Specify the number of bytes per logical sector. Must be a power
122 of 2 and greater than or equal to 512, i.e. 512, 1024, 2048,
123 4096, 8192, 16384, or 32768.
124 -v Verbose execution.
126
128 mkdosfs can not create bootable filesystems. This isn't as easy as you
129 might think at first glance for various reasons and has been discussed
130 a lot already. mkdosfs simply will not support it ;)
131
133 Dave Hudson - <dave@humbug.demon.co.uk>; modified by Peter Anvin
134 <hpa@yggdrasil.com>. Fixes and additions by Roman Hodek
135 <roman@hodek.net> for Debian/GNU Linux.
136
138 mkdosfs is based on code from mke2fs (written by Remy Card -
139 <card@masi.ibp.fr>) which is itself based on mkfs (written by Linus
140 Torvalds - <torvalds@cs.helsinki.fi>).
141
143 dosfsck(8), mkfs(8)
144Version 2.x 5 May 1995 MKDOSFS(8)