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Matt Mower18794c82015-11-11 16:22:45 -06001.\" mkfs.fat.8 - manpage for fs.fatck
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26.\"*******************************************************************
27.TH MKFS.FAT 8 2015\-05\-16 3.0.28 dosfstools
28.SH NAME
29.\" ----------------------------------------------------------------------------
30\fBmkfs.fat\fP \- create an MS\-DOS filesystem under Linux
31.SH SYNOPSIS
32.\" ----------------------------------------------------------------------------
33\fBmkfs.fat\fP [\fIOPTIONS\fP] \fIDEVICE\fP [\fIBLOCK\-COUNT\fP]
34.SH DESCRIPTION
35.\" ----------------------------------------------------------------------------
36\fBmkfs.fat\fP is used to create an MS\-DOS filesystem under Linux on a device
37(usually a disk partition). \fIDEVICE\fP is the special file corresponding to
38the device (e.g. /dev/sdXX). \fIBLOCK\-COUNT\fP is the number of blocks on the
39device. If omitted, \fBmkfs.fat\fP automatically determines the filesystem
40size.
41.SH OPTIONS
42.IP \fB\-a\fP 4
43Normally, for any filesystem except very small ones, \fBmkfs.fat\fP will align
44all the data structures to cluster size, to make sure that as long as the
45partition is properly aligned, so will all the data structures in the
46filesystem. This option disables alignment; this may provide a handful of
47additional clusters of storage at the expense of a significant performance
48degradation on RAIDs, flash media or large\-sector hard disks.
49.IP "\fB \-A\fP" 4
50Use Atari variation of the MS\-DOS filesystem. This is default if
51\fBmkfs.fat\fP is run on an Atari, then this option turns off Atari format.
52There are some differences when using Atari format: If not directed
53otherwise by the user, \fBmkfs.fat\fP will always use 2 sectors per cluster,
54since GEMDOS doesn't like other values very much. It will also obey the
55maximum number of sectors GEMDOS can handle. Larger filesystems are managed
56by raising the logical sector size. Under Atari format, an Atari\-compatible
57serial number for the filesystem is generated, and a 12 bit FAT is used only
58for filesystems that have one of the usual floppy sizes (720k, 1.2M, 1.44M,
592.88M), a 16 bit FAT otherwise. This can be overridden with the \fB\-F\fP
60option. Some PC\-specific boot sector fields aren't written, and a boot
61message (option \fB\-m\fP) is ignored.
62.IP "\fB\-b\fP \fISECTOR\-OF\-BACKUP\fP" 4
63Selects the location of the backup boot sector for FAT32. Default depends
64on number of reserved sectors, but usually is sector 6. The backup must be
65within the range of reserved sectors.
66.IP \fB\-c\fP 4
67Check the device for bad blocks before creating the filesystem.
68.IP \fB\-C\fP 4
69Create the file given as \fIDEVICE\fP on the command line, and write the
70to\-be\-created filesystem to it. This can be used to create the new
71filesystem in a file instead of on a real device, and to avoid using \fBdd\fP
72in advance to create a file of appropriate size. With this option, the
73\fIBLOCK\-COUNT\fP must be given, because otherwise the intended size of the
74filesystem wouldn't be known. The file created is a sparse file, which
75actually only contains the meta\-data areas (boot sector, FATs, and root
76directory). The data portions won't be stored on the disk, but the file
77nevertheless will have the correct size. The resulting file can be copied
78later to a floppy disk or other device, or mounted through a loop device.
79.IP "\fB\-D\fP \fIDRIVE\-NUMBER\fP" 4
80Specify the BIOS drive number to be stored in the FAT boot sector. This
81value is usually 0x80 for hard disks and 0x00 for floppy devices or
82partitions to be used for floppy emulation.
83.IP "\fB\-f\fP \fINUMBER\-OF\-FATS\fP" 4
84Specify the number of file allocation tables in the filesystem. The default
85is 2.
86.IP "\fB\-F\fP \fIFAT\-SIZE\fP" 4
87Specifies the type of file allocation tables used (12, 16 or 32 bit). If
88nothing is specified, \fBmkfs.fat\fP will automatically select between 12, 16
89and 32 bit, whatever fits better for the filesystem size.
90.IP "\fB\-h\fP \fINUMBER\-OF\-HIDDEN\-SECTORS\fP" 4
91Select the number of hidden sectors in the volume. Apparently some digital
92cameras get indigestion if you feed them a CF card without such hidden
93sectors, this option allows you to satisfy them.
94.IP "\fB\-i\fP \fIVOLUME\-ID\fP" 4
95Sets the volume ID of the newly created filesystem; \fIVOLUME\-ID\fP is a 32\-bit
96hexadecimal number (for example, 2e24ec82). The default is a number which
97depends on the filesystem creation time.
98.IP \fB\-I\fP 4
99It is typical for fixed disk devices to be partitioned so, by default, you
100are not permitted to create a filesystem across the entire device.
101\fBmkfs.fat\fP will complain and tell you that it refuses to work. This is
102different when using MO disks. One doesn't always need partitions on MO
103disks. The filesystem can go directly to the whole disk. Under other OSes
104this is known as the 'superfloppy' format. This switch will force
105\fBmkfs.fat\fP to work properly.
106.IP "\fB\-l\fP \fIFILENAME\fP" 4
107Read the bad blocks list from \fIFILENAME\fP.
108.IP "\fB\-m\fP \fIMESSAGE\-FILE\fP" 4
109Sets the message the user receives on attempts to boot this filesystem
110without having properly installed an operating system. The message file
111must not exceed 418 bytes once line feeds have been converted to carriage
112return\-line feed combinations, and tabs have been expanded. If the filename
113is a hyphen (\-), the text is taken from standard input.
114.IP "\fB\-M\fP \fIFAT\-MEDIA\-TYPE\fP" 4
115Specify the media type to be stored in the FAT boot sector. This value is
116usually 0xF8 for hard disks and is 0xF0 or a value from 0xF9 to 0xFF for
117floppies or partitions to be used for floppy emulation.
118.IP "\fB\-n\fP \fIVOLUME\-NAME\fP" 4
119Sets the volume name (label) of the filesystem. The volume name can be up
120to 11 characters long. The default is no label.
121.IP "\fB\-r\fP \fIROOT\-DIR\-ENTRIES\fP" 4
122Select the number of entries available in the root directory. The default
123is 112 or 224 for floppies and 512 for hard disks.
124.IP "\fB\-R\fP \fINUMBER\-OF\-RESERVED\-SECTORS\fP" 4
125Select the number of reserved sectors. With FAT32 format at least 2
126reserved sectors are needed, the default is 32. Otherwise the default is 1
127(only the boot sector).
128.IP "\fB\-s\fP \fISECTORS\-PER\-CLUSTER\fP" 4
129Specify the number of disk sectors per cluster. Must be a power of 2,
130i.e. 1, 2, 4, 8, ... 128.
131.IP "\fB\-S\fP \fILOGICAL\-SECTOR\-SIZE\fP" 4
132Specify the number of bytes per logical sector. Must be a power of 2 and
133greater than or equal to 512, i.e. 512, 1024, 2048, 4096, 8192, 16384, or
13432768.
135.IP \fB\-v\fP 4
136Verbose execution.
137.IP \fB\-\-invariant\fP 4
138Use constants for normally randomly generated or time based data such as
139volume ID and creation time. Multiple runs of \fBmkfs.fat\fP on the same
140device create identical results with this option. Its main purpose is
141testing \fBmkfs.fat\fP.
142.IP \fB\-\-help\fP 4
143.\" ----------------------------------------------------------------------------
144Display option summary and exit.
145.SH BUGS
146.\" ----------------------------------------------------------------------------
147\fBmkfs.fat\fP can not create boot\-able filesystems. This isn't as easy as you
148might think at first glance for various reasons and has been discussed a lot
149already. \fBmkfs.fat\fP simply will not support it ;)
150.SH "SEE ALSO"
151\fBfatlabel\fP(8)
152.br
153.\" ----------------------------------------------------------------------------
154\fBfsck.fat\fP(8)
155.SH HOMEPAGE
156.\" ----------------------------------------------------------------------------
157The home for the \fBdosfstools\fP project is its
158.UR https://github.com/dosfstools/dosfstools
159GitHub project page
160.UE .
161.SH AUTHORS
162\fBdosfstools\fP were written by
163.MT werner.almesberger@\:lrc.di.epfl.ch
164Werner Almesberger
165.ME ,
166.MT Roman.Hodek@\:informatik.\:uni-erlangen.de
167Roman Hodek
168.ME ,
169and others. The current maintainer is
170.MT aeb@\:debian.org
171Andreas Bombe
172.ME .