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DOSFSCK(8)			       MAINTENANCE COMMANDS			       DOSFSCK(8)

NAME
       dosfsck - check and repair MS-DOS file systems

SYNOPSIS
       dosfsck|fsck.msdos|fsck.vfat [-aAflnrtvVwy] [-d path -d ...]  [-u path -u ...]  device

DESCRIPTION
       dosfsck	verifies  the  consistency  of MS-DOS file systems and optionally tries to repair
       them. The following file system 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 file names. 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 trun-
	      cated.
       -      Two or more files share the same cluster(s). All but one of  the	files  are  trun-
	      cated.  If the file being truncated is a directory file that has already been read,
	      the file system 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 file system, 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 file system. 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 file system. 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 file system 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.

       If -a and -r are absent, the file system 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  incon-
	      sistency.

       2      Usage error. dosfsck did not access the file system.

FILES
       fsck0000.rec, fsck0001.rec, ...
	      When  recovering	from  a  corrupted file system, dosfsck dumps recovered data into
	      files named 'fsckNNNN.rec' in the top level directory of the file system.

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.

AUTHORS
       Werner Almesberger <werner.almesberger@lrc.di.epfl.ch> Extensions  (FAT32,  VFAT)  by  and
       current maintainer: Roman Hodek <roman@hodek.net>

Linux					 December 31 1997			       DOSFSCK(8)
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