1FSCK.FAT(8) dosfstools FSCK.FAT(8)
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6 fsck.fat - check and repair MS-DOS filesystems
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10 fsck.fat|fsck.msdos|fsck.vfat [-aAflnprtvVwy] [-d PATH -d ...] [-u PATH
11 -u ...] DEVICE
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15 fsck.fat verifies the consistency of MS-DOS filesystems and optionally
16 tries to repair them.
17 The following filesystem problems can be corrected (in this order):
19 * FAT contains invalid cluster numbers. Cluster is changed to EOF.
21 * File's cluster chain contains a loop. The loop is broken.
23 * Bad clusters (read errors). The clusters are marked bad and they
25 are removed from files owning them. This check is optional.
26 * Directories with a large number of bad entries (probably corrupt).
28 The directory can be deleted.
29 * Files . and .. are non-directories. They can be deleted or renamed.
31 * Directories . and .. in root directory. They are deleted.
33 * Bad filenames. They can be renamed.
35 * Duplicate directory entries. They can be deleted or renamed.
37 * Directories with non-zero size field. Size is set to zero.
39 * Directory . does not point to parent directory. The start pointer
41 is adjusted.
42 * Directory .. does not point to parent of parent directory. The
44 start pointer is adjusted.
45 * Start cluster number of a file is invalid. The file is truncated.
47 * File contains bad or free clusters. The file is truncated.
49 * File's cluster chain is longer than indicated by the size fields.
51 The file is truncated.
52 * Two or more files share the same cluster(s). All but one of the
54 files are truncated. If the file being truncated is a directory
55 file that has already been read, the filesystem check is restarted
56 after truncation.
57 * File's cluster chain is shorter than indicated by the size fields.
59 The file is truncated.
60 * Clusters are marked as used but are not owned by a file. They are
62 marked as free.
63 Additionally, the following problems are detected, but not repaired:
65 * Invalid parameters in boot sector.
67 * Absence of . and .. entries in non-root directories
69 When fsck.fat checks a filesystem, it accumulates all changes in memory
71 and performs them only after all checks are complete. This can be dis‐
72 abled with the -w option.
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76 -a Automatically repair the filesystem. No user intervention is neces‐
77 sary. Whenever there is more than one method to solve a problem,
78 the least destructive approach is used.
79 -A Use Atari variation of the MS-DOS filesystem. This is default if
81 fsck.fat is run on an Atari, then this option turns off Atari for‐
82 mat. There are some minor differences in Atari format: Some boot
83 sector fields are interpreted slightly different, and the special
84 FAT entries for end-of-file and bad cluster can be different. Under
85 MS-DOS 0xfff8 is used for EOF and Atari employs 0xffff by default,
86 but both systems recognize all values from 0xfff8...0xffff as
87 end-of-file. MS-DOS uses only 0xfff7 for bad clusters, where on
88 Atari values 0xfff0...0xfff7 are for this purpose (but the standard
89 value is still 0xfff7).
90 -b Make read-only boot sector check.
92 -d Delete the specified file. If more that one file with that name
94 exists, the first one is deleted.
95 -f Salvage unused cluster chains to files. By default, unused clusters
97 are added to the free disk space except in auto mode (-a).
98 -l List path names of files being processed.
100 -n No-operation mode: non-interactively check for errors, but don't
102 write anything to the filesystem.
103 -p Same as (-a), for compatibility with other *fsck.
105 -r Interactively repair the filesystem. The user is asked for advice
107 whenever there is more than one approach to fix an inconsistency.
108 -t Mark unreadable clusters as bad.
110 -u Try to undelete the specified file. fsck.fat tries to allocate a
112 chain of contiguous unallocated clusters beginning with the start
113 cluster of the undeleted file.
114 -v Verbose mode. Generates slightly more output.
116 -V Perform a verification pass. The filesystem check is repeated after
118 the first run. The second pass should never report any fixable
119 errors. It may take considerably longer than the first pass,
120 because the first pass may have generated long list of modifica‐
121 tions that have to be scanned for each disk read.
122 -w Write changes to disk immediately.
124 -y Same as -a (automatically repair filesystem) for compatibility with
126 other fsck tools.
127 Note: If -a and -r are absent, the filesystem is only checked, but not
129 repaired.
130
133 0 No recoverable errors have been detected.
134 1 Recoverable errors have been detected or fsck.fat has discovered an
136 internal inconsistency.
137 2 Usage error. fsck.fat did not access the filesystem.
139
142 fsck0000.rec, fsck0001.rec, ...
143 When recovering from a corrupted filesystem, fsck.fat dumps recov‐
144 ered data into files named 'fsckNNNN.rec' in the top level direc‐
145 tory of the filesystem.
146
149 Does not create . and .. files where necessary. Does not remove
150 entirely empty directories. Should give more diagnostic messages.
151 Undeleting files should use a more sophisticated algorithm.
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155 fatlabel(8)
156 mkfs.fat(8)
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160 More information about fsck.fat and dosfstools can be found at
161 <http://daniel-baumann.ch/software/dosfstools/>.
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165 dosfstools were written by Werner Almesberger <werner.almes‐
166 berger@lrc.di.epfl.ch>, Roman Hodek <Roman.Hodek@informatik.uni-erlan‐
167 gen.de>, and others. The current maintainer is Daniel Baumann
168 <mail@daniel-baumann.ch>.
1693.0.19 2013-06-11 FSCK.FAT(8)