1FSCK.FAT(8) System Manager's Manual FSCK.FAT(8)
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6 fsck.fat - check and repair MS-DOS filesystems
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9 fsck.fat [OPTIONS] DEVICE
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12 fsck.fat verifies the consistency of MS-DOS filesystems and optionally
13 tries to repair them.
14 The following filesystem problems can be corrected (in this order):
16 * FAT contains invalid cluster numbers. Cluster is changed to EOF.
18 * File's cluster chain contains a loop. The loop is broken.
20 * Bad clusters (read errors). The clusters are marked bad and they
22 are removed from files owning them. This check is optional.
23 * Directories with a large number of bad entries (probably corrupt).
25 The directory can be deleted.
26 * Files . and .. are non-directories. They can be deleted or
28 renamed.
29 * Directories . and .. in root directory. They are deleted.
31 * Bad filenames. They can be renamed.
33 * Duplicate directory entries. They can be deleted or renamed.
35 * Directories with non-zero size field. Size is set to zero.
37 * Directory . does not point to parent directory. The start pointer
39 is adjusted.
40 * Directory .. does not point to parent of parent directory. The
42 start pointer is adjusted.
43 * Start cluster number of a file is invalid. The file is truncated.
45 * File contains bad or free clusters. The file is truncated.
47 * File's cluster chain is longer than indicated by the size fields.
49 The file is truncated.
50 * Two or more files share the same cluster(s). All but one of the
52 files are truncated. If the file being truncated is a directory
53 file that has already been read, the filesystem check is restarted
54 after truncation.
55 * File's cluster chain is shorter than indicated by the size fields.
57 The file is truncated.
58 * Clusters are marked as used but are not owned by a file. They are
60 marked as free.
61 Additionally, the following problems are detected, but not repaired:
63 * Invalid parameters in boot sector
65 * Absence of . and .. entries in non-root directories
67 When fsck.fat checks a filesystem, it accumulates all changes in memory
69 and performs them only after all checks are complete. This can be dis‐
70 abled with the -w option.
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73 -a Automatically repair the filesystem. No user intervention is nec‐
74 essary. Whenever there is more than one method to solve a problem,
75 the least destructive approach is used.
76 -A Use Atari variation of the MS-DOS filesystem. This is default if
78 fsck.fat is run on an Atari, then this option turns off Atari for‐
79 mat. There are some minor differences in Atari format: Some boot
80 sector fields are interpreted slightly different, and the special
81 FAT entries for end-of-file and bad cluster can be different.
82 Under MS-DOS 0xfff8 is used for EOF and Atari employs 0xffff by
83 default, but both systems recognize all values from 0xfff8...0xffff
84 as end-of-file. MS-DOS uses only 0xfff7 for bad clusters, where on
85 Atari values 0xfff0...0xfff7 are for this purpose (but the standard
86 value is still 0xfff7).
87 -b Make read-only boot sector check.
89 -c PAGE
91 Use DOS codepage PAGE to decode short file names. By default code‐
92 page 437 is used.
93 -d PATH
95 Delete the specified file. If more than one file with that name
96 exist, the first one is deleted. This option can be given more
97 than once.
98 -f Salvage unused cluster chains to files. By default, unused clus‐
100 ters are added to the free disk space except in auto mode (-a).
101 -l List path names of files being processed.
103 -n No-operation mode: non-interactively check for errors, but don't
105 write anything to the filesystem.
106 -p Same as -a, for compatibility with other *fsck.
108 -r Interactively repair the filesystem. The user is asked for advice
110 whenever there is more than one approach to fix an inconsistency.
111 This is the default mode and the option is only retained for back‐
112 wards compatibility.
113 -t Mark unreadable clusters as bad.
115 -u PATH
117 Try to undelete the specified file. fsck.fat tries to allocate a
118 chain of contiguous unallocated clusters beginning with the start
119 cluster of the undeleted file. This option can be given more than
120 once.
121 -v Verbose mode. Generates slightly more output.
123 -V Perform a verification pass. The filesystem check is repeated
125 after the first run. The second pass should never report any fix‐
126 able errors. It may take considerably longer than the first pass,
127 because the first pass may have generated long list of modifica‐
128 tions that have to be scanned for each disk read.
129 -w Write changes to disk immediately.
131 -y Same as -a (automatically repair filesystem) for compatibility with
133 other fsck tools.
134
136 0 No recoverable errors have been detected.
137 1 Recoverable errors have been detected or fsck.fat has discovered an
139 internal inconsistency.
140 2 Usage error. fsck.fat did not access the filesystem.
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144 fsck0000.rec, fsck0001.rec, ...
145 When recovering from a corrupted filesystem, fsck.fat dumps recov‐
146 ered data into files named 'fsckNNNN.rec' in the top level direc‐
147 tory of the filesystem.
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150 Does not create . and .. files where necessary. Does not remove
151 entirely empty directories. Should give more diagnostic messages.
152 Undeleting files should use a more sophisticated algorithm.
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155 fatlabel(8)
156 mkfs.fat(8)
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159 The home for the dosfstools project is its GitHub project page
160 ⟨https://github.com/dosfstools/dosfstools⟩.
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163 dosfstools were written by Werner Almesberger ⟨werner.almesberger@
164 lrc.di.epfl.ch⟩, Roman Hodek ⟨Roman.Hodek@informatik.uni-erlangen.de⟩,
165 and others. The current maintainer is Andreas Bombe ⟨aeb@debian.org⟩.
166dosfstools 4.1 2015-04-16 FSCK.FAT(8)