dosfsck(8) - phpMan

FSCK.FAT(8) System Manager's Manual FSCK.FAT(8)

NAME
fsck.fat - check and repair MS-DOS filesystems

SYNOPSIS
fsck.fat [OPTIONS] DEVICE

DESCRIPTION
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 ad-
justed.

* 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 trun-
cated.

* 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 trun-
cated.

* 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.

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 fsck.fat 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 clus-
ters, where on Atari values 0xfff0...0xfff7 are for this purpose (but the standard
value is still 0xfff7).

-b Make read-only boot sector check.

-c PAGE
Use DOS codepage PAGE to decode short file names. By default codepage 437 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 op-
tion is only retained for backwards compatibility.

-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 op-
tion 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.

-w Write changes to disk immediately.

-y Same as -a (automatically repair filesystem) for compatibility with other fsck tools.

EXIT STATUS
0 No recoverable errors have been detected.

1 Recoverable errors have been detected or fsck.fat has discovered an internal inconsis-
tency.

2 Usage error. fsck.fat did not access the filesystem.

FILES
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.

BUGS
Does not create . and .. files where necessary. Does not remove entirely empty directo-
ries. Should give more diagnostic messages. Undeleting files should use a more sophisti-
cated algorithm.