1MKDOSFS(8) System Manager's Manual MKDOSFS(8)
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6 mkdosfs - create an MS-DOS file system under Linux
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9 mkdosfs|mkfs.msdos|mkfs.vfat [ -a ] [ -A ] [ -b sector-of-backup ] [ -c
10 ] [ -l filename ] [ -C ] [ -f number-of-FATs ] [ -F FAT-size ] [ -h
11 number-of-hidden-sectors ] [ -i volume-id ] [ -I ] [ -m message-file ]
12 [ -n volume-name ] [ -r root-dir-entries ] [ -R number-of-reserved-sec‐
13 tors ] [ -s sectors-per-cluster ] [ -S logical-sector-size ] [ -v ]
14 device [ block-count ]
15
17 mkdosfs is used to create an MS-DOS file system under Linux on a device
18 (usually a disk partition). device is the special file corresponding
19 to the device (e.g /dev/hdXX). block-count is the number of blocks on
20 the device. If omitted, mkdosfs automatically determines the file sys‐
21 tem size.
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24 -a Normally, for any filesystem except very small ones, mkdosfs
25 will align all the data structures to cluster size, to make sure
26 that as long as the partition is properly aligned, so will all
27 the data structures in the filesystem. This option disables
28 alignment; this may provide a handful of additional clusters of
29 storage at the expense of a significant performance degradation
30 on RAIDs, flash media or large-sector hard disks.
31 -A Use Atari variation of the MS-DOS file system. This is default
33 if mkdosfs is run on an Atari, then this option turns off Atari
34 format. There are some differences when using Atari format: If
35 not directed otherwise by the user, mkdosfs will always use 2
36 sectors per cluster, since GEMDOS doesn't like other values very
37 much. It will also obey the maximum number of sectors GEMDOS
38 can handle. Larger file systems are managed by raising the log‐
39 ical sector size. Under Atari format, an Atari-compatible
40 serial number for the file system is generated, and a 12 bit FAT
41 is used only for file systems that have one of the usual floppy
42 sizes (720k, 1.2M, 1.44M, 2.88M), a 16 bit FAT otherwise. This
43 can be overridden with the -F option. Some PC-specific boot sec‐
44 tor fields aren't written, and a boot message (option -m) is
45 ignored.
46 -b sector-of-backup
48 Selects the location of the backup boot sector for FAT32.
49 Default depends on number of reserved sectors, but usually is
50 sector 6. The backup must be within the range of reserved sec‐
51 tors.
52 -c Check the device for bad blocks before creating the file system.
54 -C Create the file given as device on the command line, and write
56 the to-be-created file system to it. This can be used to create
57 the new file system in a file instead of on a real device, and
58 to avoid using dd in advance to create a file of appropriate
59 size. With this option, the block-count must be given, because
60 otherwise the intended size of the file system wouldn't be
61 known. The file created is a sparse file, which actually only
62 contains the meta-data areas (boot sector, FATs, and root direc‐
63 tory). The data portions won't be stored on the disk, but the
64 file nevertheless will have the correct size. The resulting file
65 can be copied later to a floppy disk or other device, or mounted
66 through a loop device.
67 -f number-of-FATs
69 Specify the number of file allocation tables in the file system.
70 The default is 2. Currently the Linux MS-DOS file system does
71 not support more than 2 FATs.
72 -F FAT-size
74 Specifies the type of file allocation tables used (12, 16 or 32
75 bit). If nothing is specified, mkdosfs will automatically
76 select between 12, 16 and 32 bit, whatever fits better for the
77 file system size.
78 -h number-of-hidden-sectors
80 Select the number of hidden sectors in the volume. Apparently
81 some digital cameras get indigestion if you feed them a CF card
82 without such hidden sectors, this option allows you to satisfy
83 them. Assumes ´0´ if no value is given on the command line.
84 -i volume-id
86 Sets the volume ID of the newly created file system; volume-id
87 is a 32-bit hexadecimal number (for example, 2e24ec82). The
88 default is a number which depends on the file system creation
89 time.
90 -I It is typical for fixed disk devices to be partitioned so, by
92 default, you are not permitted to create a filesystem across the
93 entire device. mkdosfs will complain and tell you that it
94 refuses to work. This is different when using MO disks. One
95 doesn't always need partitions on MO disks. The file system can
96 go directly to the whole disk. Under other OSes this is known
97 as the 'superfloppy' format.
98 This switch will force mkdosfs to work properly.
100 -l filename
102 Read the bad blocks list from filename.
103 -m message-file
105 Sets the message the user receives on attempts to boot this file
106 system without having properly installed an operating system.
107 The message file must not exceed 418 bytes once line feeds have
108 been converted to carriage return-line feed combinations, and
109 tabs have been expanded. If the filename is a hyphen (-), the
110 text is taken from standard input.
111 -n volume-name
113 Sets the volume name (label) of the file system. The volume
114 name can be up to 11 characters long. The default is no label.
115 -r root-dir-entries
117 Select the number of entries available in the root directory.
118 The default is 112 or 224 for floppies and 512 for hard disks.
119 -R number-of-reserved-sectors
121 Select the number of reserved sectors. With FAT32 format at
122 least 2 reserved sectors are needed, the default is 32. Other‐
123 wise the default is 1 (only the boot sector).
124 -s sectors-per-cluster
126 Specify the number of disk sectors per cluster. Must be a power
127 of 2, i.e. 1, 2, 4, 8, ... 128.
128 -S logical-sector-size
130 Specify the number of bytes per logical sector. Must be a power
131 of 2 and greater than or equal to 512, i.e. 512, 1024, 2048,
132 4096, 8192, 16384, or 32768.
133 -v Verbose execution.
135
137 mkdosfs can not create boot-able file systems. This isn't as easy as
138 you might think at first glance for various reasons and has been dis‐
139 cussed a lot already. mkdosfs simply will not support it ;)
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142 Dave Hudson - <dave@humbug.demon.co.uk>; modified by Peter Anvin
143 <hpa@yggdrasil.com>. Fixes and additions by Roman Hodek
144 <roman@hodek.net> for Debian/GNU Linux.
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147 mkdosfs is based on code from mke2fs (written by Remy Card -
148 <card@masi.ibp.fr>) which is itself based on mkfs (written by Linus
149 Torvalds - <torvalds@cs.helsinki.fi>).
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152 dosfsck(8), dosfslabel(8), mkfs(8)
153Version 2.x 5 May 1995 MKDOSFS(8)