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 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  com-
       plete. 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 inconsistency.

       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 directories. Should give more diagnostic
       messages. Undeleting files should use a more sophisticated algorithm.

AUTHORS
       Werner Almesberger <werner.almesbergerATlrc.ch> Extensions (FAT32, VFAT) by and current  maintainer:  Roman  Hodek
       <romanAThodek.net>



Linux                                                   December 31 1997                                              DOSFSCK(8)