NAME¶
dosfsck - check and repair MS-DOS filesystems
SYNOPSIS¶
dosfsck|
fsck.msdos|
fsck.vfat [-aAflnrtvVwy] [-d
PATH
-d
...] [-u
PATH -u
...]
DEVICE
DESCRIPTION¶
dosfsck 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
dosfsck 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.
OPTIONS¶
- -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
- Use Atari variation of the MS-DOS filesystem. This is
default if dosfsck is run on an Atari, then this option turns off
Atari format. 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).
- -d
- Delete the specified file. If more that one file with that
name exists, the first one is deleted.
- -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.
- -r
- Interactively repair the filesystem. The user is asked for
advice whenever there is more than one approach to fix an
inconsistency.
- -t
- Mark unreadable clusters as bad.
- -u
- Try to undelete the specified file. dosfsck tries to
allocate a chain of contiguous unallocated clusters beginning with the
start cluster of the undeleted file.
- -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.
- -w
- Write changes to disk immediately.
- -y
- Same as -a (automatically repair filesystem) for
compatibility with other fsck tools.
Note: If
-a and
-r are absent, the filesystem is only
checked, but not repaired.
EXIT STATUS¶
- 0
- No recoverable errors have been detected.
- 1
- Recoverable errors have been detected or dosfsck has
discovered an internal inconsistency.
- 2
- Usage error. dosfsck did not access the filesystem.
FILES¶
- fsck0000.rec, fsck0001.rec, ...
- When recovering from a corrupted filesystem, dosfsck
dumps recovered data into files named 'fsckNNNN.rec' in the top level
directory of the filesystem.
BUGS¶
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.
SEE ALSO¶
dosfslabel(8)
mkdosfs(8)
HOMEPAGE¶
More information about
dosfsck and
dosfstools can be found at
<
http://www.daniel-baumann.ch/software/dosfstools/>.
AUTHORS¶
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 Daniel Baumann <
daniel@debian.org>.