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       dosfsck - check and repair MS-DOS file systems


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


       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
       -      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
       -      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  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.


       -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

       -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

       -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


       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 file system.


       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.


       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.


       Werner   Almesberger   <>   Extensions
       (FAT32, VFAT) by and current maintainer: Roman Hodek <>