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- .TH DOSFSCK 8 "December 31 1997" "Linux" "MAINTENANCE COMMANDS"
- .SH NAME
- dosfsck \- check and repair MS-DOS file systems
- .SH SYNOPSIS
- .ad l
- .B dosfsck|fsck.msdos|fsck.vfat
- .RB [ \-aAflnrtvVwy ]
- .RB [ \-d\ \fIpath\fB\ \-d\ \fI...\fB ]
- .RB [ \-u\ \fIpath\fB\ \-u\ \fI...\fB ]
- .I device
- .ad b
- .SH DESCRIPTION
- .B 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):
- .IP \-
- FAT contains invalid cluster numbers. Cluster is changed to EOF.
- .PD 0
- .IP \-
- File's cluster chain contains a loop. The loop is broken.
- .IP \-
- Bad clusters (read errors). The clusters are marked bad and they are
- removed from files owning them. This check is optional.
- .IP \-
- Directories with a large number of bad entries (probably corrupt). The
- directory can be deleted.
- .IP \-
- Files . and .. are non-directories. They can be deleted or renamed.
- .IP \-
- Directories . and .. in root directory. They are deleted.
- .IP \-
- Bad file names. They can be renamed.
- .IP \-
- Duplicate directory entries. They can be deleted or renamed.
- .IP \-
- Directories with non-zero size field. Size is set to zero.
- .IP \-
- Directory . does not point to parent directory. The start pointer is
- adjusted.
- .IP \-
- Directory .. does not point to parent of parent directory. The start pointer
- is adjusted.
- .IP \-
- Start cluster number of a file is invalid. The file is truncated.
- .IP \-
- File contains bad or free clusters. The file is truncated.
- .IP \-
- File's cluster chain is longer than indicated by the size fields. The file
- is truncated.
- .IP \-
- 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.
- .IP \-
- File's cluster chain is shorter than indicated by the size fields. The file
- is truncated.
- .IP \-
- Clusters are marked as used but are not owned by a file. They are marked
- as free.
- .PD
- .LP
- Additionally, the following problems are detected, but not repaired:
- .IP \-
- Invalid parameters in boot sector.
- .PD 0
- .IP \-
- Absence of . and .. entries in non-root directories
- .PD
- .LP
- When \fBdosfsck\fP 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 \fB\-w\fP option.
- .SH OPTIONS
- .IP \fB\-a\fP
- 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.
- .IP \fB\-A\fP
- Use Atari variation of the MS-DOS filesystem. This is default if
- \fBdosfsck\fP 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).
- .IP \fB\-d\fP
- Delete the specified file. If more that one file with that name exists, the
- first one is deleted.
- .IP \fB\-f\fP
- Salvage unused cluster chains to files. By default, unused clusters are
- added to the free disk space except in auto mode (\fB-a\fP).
- .IP \fB\-l\fP
- List path names of files being processed.
- .IP \fB\-n\fP
- No-operation mode: non-interactively check for errors, but don't write
- anything to the filesystem.
- .IP \fB\-r\fP
- Interactively repair the file system. The user is asked for advice whenever
- there is more than one approach to fix an inconsistency.
- .IP \fB\-t\fP
- Mark unreadable clusters as bad.
- .IP \fB-u\fP
- Try to undelete the specified file. \fBdosfsck\fP tries to allocate a chain
- of contiguous unallocated clusters beginning with the start cluster of the
- undeleted file.
- .IP \fB\-v\fP
- Verbose mode. Generates slightly more output.
- .IP \fB\-V\fP
- 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.
- .IP \fB\-w\fP
- Write changes to disk immediately.
- .IP \fB\-y\fP
- Same as \fB\-a\fP (automatically repair filesystem) for compatibility
- with other fsck tools.
- .LP
- If \fB\-a\fP and \fB\-r\fP are absent, the file system is only checked,
- but not repaired.
- .SH "EXIT STATUS"
- .IP 0
- No recoverable errors have been detected.
- .IP 1
- Recoverable errors have been detected or \fBdosfsck\fP has discovered an
- internal inconsistency.
- .IP 2
- Usage error. \fBdosfsck\fP did not access the file system.
- .SH FILES
- .IP "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.
- .SH 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.
- .\".SH "SEE ALSO"
- .\"fs(5)
- .SH AUTHORS
- Werner Almesberger <werner.almesberger@lrc.di.epfl.ch>
- Extensions (FAT32, VFAT) by and current maintainer:
- Roman Hodek <roman@hodek.net>
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