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 cor-
       rected (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 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 for-
	      mat. 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  direc-
	      tory of the file system.

BUGS

       Does  not create . and .. files where necessary. Does not remove entirely empty directories. Should give more diagnostic messages. Undelet-
       ing files should use a more sophisticated 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)