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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | FILES | BUGS | SEE ALSO | HOMEPAGE | AUTHORS | COLOPHON |
FSCK.FAT(8) System Manager's Manual FSCK.FAT(8)
fsck.fat - check and repair MS-DOS FAT filesystems
fsck.fat [OPTIONS] DEVICE
fsck.fat verifies the consistency of MS-DOS filesystems and
optionally tries to repair them.
The following filesystem problems can be corrected (in this order):
* FAT contains invalid cluster numbers. Cluster is changed to EOF.
* File's cluster chain contains a loop. The loop is broken.
* Bad clusters (read errors). The clusters are marked bad and they
are removed from files owning them. This check is optional.
* Directories with a large number of bad entries (probably
corrupt). The directory can be deleted.
* Files . and .. are non-directories. They can be deleted or
renamed.
* Directories . and .. in root directory. They are deleted.
* Bad filenames. They can be renamed.
* Duplicate directory entries. They can be deleted or renamed.
* Directories with non-zero size field. Size is set to zero.
* Directory . does not point to parent directory. The start
pointer is adjusted.
* Directory .. does not point to parent of parent directory. The
start pointer is adjusted.
* Start cluster number of a file is invalid. The file is
truncated.
* File contains bad or free clusters. The file is truncated.
* File's cluster chain is longer than indicated by the size fields.
The file is truncated.
* Two or more files share the same cluster(s). All but one of the
files are truncated. If the file being truncated is a directory
file that has already been read, the filesystem check is
restarted after truncation.
* File's cluster chain is shorter than indicated by the size
fields. The file is truncated.
* Clusters are marked as used but are not owned by a file. They
are marked as free.
Additionally, the following problems are detected, but not repaired:
* Invalid parameters in boot sector
* Absence of . and .. entries in non-root directories
When fsck.fat checks a filesystem, it accumulates all changes in
memory and performs them only after all checks are complete. This
can be disabled with the -w option.
Two different variants of the FAT filesystem are supported. Standard
is the FAT12, FAT16 and FAT32 filesystems as defined by Microsoft and
widely used on hard disks and removable media like USB sticks and SD
cards. The other is the legacy Atari variant used on Atari ST.
There are some minor differences in Atari format: Some boot sector
fields are interpreted slightly different, and the special FAT
entries for end-of-file and bad cluster can be different. Under
MS-DOS 0xfff8 is used for EOF and Atari employs 0xffff by default,
but both systems recognize all values from 0xfff8...0xffff as
end-of-file. MS-DOS uses only 0xfff7 for bad clusters, where on
Atari values 0xfff0...0xfff7 are for this purpose (but the standard
value is still 0xfff7).
-a Automatically repair the filesystem. No user intervention is
necessary. Whenever there is more than one method to solve a
problem, the least destructive approach is used.
-A Select using the Atari variation of the FAT filesystem if that
isn't active already, otherwise select standard FAT filesystem.
This is selected by default if mkfs.fat is run on 68k Atari
Linux.
-b Make read-only boot sector check.
-c PAGE
Use DOS codepage PAGE to decode short file names. By default
codepage 850 is used.
-d PATH
Delete the specified file. If more than one file with that name
exist, the first one is deleted. This option can be given more
than once.
-f Salvage unused cluster chains to files. By default, unused
clusters are added to the free disk space except in auto mode
(-a).
-l List path names of files being processed.
-n No-operation mode: non-interactively check for errors, but don't
write anything to the filesystem.
-p Same as -a, for compatibility with other *fsck.
-r Interactively repair the filesystem. The user is asked for
advice whenever there is more than one approach to fix an
inconsistency. This is the default mode and the option is only
retained for backwards compatibility.
-S Consider short (8.3) file names with spaces in the middle to be
invalid, like previous versions of this program did. While such
file names are not forbidden by the FAT specification, and were
never treated as errors by Microsoft file system checking tools,
many DOS programs are unable to handle files with such names.
Using this option can make them accessible to these programs.
Short file names which start with a space are considered invalid
regardless of this option's setting.
Previous versions of this program exceptionally treated "EA DATA
. SF" and "WP ROOT . SF" as valid short names; using this option
does not preserve that exception.
-t Mark unreadable clusters as bad.
-u PATH
Try to undelete the specified file. fsck.fat tries to allocate a
chain of contiguous unallocated clusters beginning with the start
cluster of the undeleted file. This option can be given more
than once.
-v Verbose mode. Generates slightly more output.
-V Perform a verification pass. The filesystem check is repeated
after the first run. The second pass should never report any
fixable errors. It may take considerably longer than the first
pass, because the first pass may have generated long list of
modifications that have to be scanned for each disk read.
--variant TYPE
Create a filesystem of variant TYPE. Acceptable values are
'standard' and 'atari' (in any combination of upper/lower case).
See above under DESCRIPTION for the differences.
-w Write changes to disk immediately.
-y Same as -a (automatically repair filesystem) for compatibility
with other fsck tools.
--help
Display help message describing usage and options then exit.
0 No recoverable errors have been detected.
1 Recoverable errors have been detected or fsck.fat has discovered
an internal inconsistency.
2 Usage error. fsck.fat did not access the filesystem.
fsck0000.rec, fsck0001.rec, ...
When recovering from a corrupted filesystem, fsck.fat dumps
recovered data into files named 'fsckNNNN.rec' in the top level
directory of the filesystem.
Does not create . and .. files where necessary. Does not remove
entirely empty directories. Should give more diagnostic messages.
Undeleting files should use a more sophisticated algorithm.
fatlabel(8), mkfs.fat(8)
The home for the dosfstools project is its GitHub project page
⟨https://github.com/dosfstools/dosfstools⟩.
dosfstools were written by Werner Almesberger ⟨werner.almesberger@
lrc.di.epfl.ch⟩, Roman Hodek ⟨Roman.Hodek@informatik.uni-
erlangen.de⟩, and others. The current maintainer is Andreas Bombe
⟨aeb@debian.org⟩.
This page is part of the dosfstools (Tools for making and checking
MS-DOS FAT filesystems) project. Information about the project can
be found at ⟨https://github.com/dosfstools/dosfstools⟩. If you have
a bug report for this manual page, see
⟨https://github.com/dosfstools/dosfstools/issues⟩. This page was
obtained from the project's upstream Git repository
⟨https://github.com/dosfstools/dosfstools.git⟩ on 2020-08-13. (At
that time, the date of the most recent commit that was found in the
repository was 2020-02-14.) If you discover any rendering problems
in this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
dosfstools 4.1+git 2017-06-28 FSCK.FAT(8)
Pages that refer to this page: fsck(8@@e2fsprogs) , fsck(8)