Provided by: dosfstools_4.2-1build1_amd64 bug

NAME

       fsck.fat - check and repair MS-DOS FAT filesystems

SYNOPSIS

       fsck.fat [OPTIONS] DEVICE

DESCRIPTION

       fsck.fat  verifies  the  consistency  of MS-DOS filesystems and optionally tries to repair
       them.

       The following filesystem 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 filenames.  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.

       ·   .  and  ..  are  not  the  two first entries in a non-root directory.  The entries are
           created, moving occupied slots if necessary.

       ·   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
           filesystem check is restarted after truncation.

       ·   File's  cluster  chain  is  shorter  than  indicated  by the size fields.  The file is
           truncated.

       ·   Volume label in root directory or label in boot sector is invalid.  Invalid labels are
           removed.

       ·   Volume  label  in root directory and label in boot sector are different.  Volume label
           from root directory is copied to boot sector.

       ·   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

       When fsck.fat checks a filesystem, it accumulates all changes in memory and performs  them
       only after all checks are complete.  This can be disabled with the -w option.

       Two  different variants of the FAT filesystem are supported.  Standard is the FAT12, FAT16
       and FAT32 filesystems as defined by Microsoft and widely used on hard disks and  removable
       media  like  USB sticks and SD cards.  The other is the legacy Atari variant used on Atari
       ST.

       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).

OPTIONS

       -a  Automatically  repair  the  filesystem.   No user intervention is necessary.  Whenever
           there is more than one method to solve a problem, the least  destructive  approach  is
           used.

       -A  Select  using  the Atari variation of the FAT filesystem if that isn't active already,
           otherwise select standard FAT filesystem.  This is selected by default if mkfs.fat  is
           run on 68k Atari Linux.

       -b  Make read-only boot sector check.

       -c PAGE
           Use DOS codepage PAGE to decode short file names.  By default codepage 850 is used.

       -d PATH
           Delete  the specified file.  If more than one file with that name exist, the first one
           is deleted.  This option can be given more than once.

       -f  Salvage unused cluster chains to files.  By default, unused clusters are added to  the
           free disk space except in auto mode (-a).

       -F NUM
           Specify  FAT  table NUM for filesystem access.  By default value 0 is assumed and then
           the first uncorrupted FAT table is chosen.  Uncorrupted means that FAT table has valid
           first  cluster.   If  default  value  0  is used and all FAT tables are corrupted then
           fsck.fat gives up and does not try to repair FAT filesystem.  If non-zero NUM value is
           specified then fsck.fat uses FAT table NUM for repairing FAT filesystem.  If FAT table
           NUM has corrupted first cluster then fsck.fat will repair it.  In  any  case,  if  FAT
           filesystem  has more FAT tables then repaired content of chosen FAT table is copied to
           other FAT tables.  To repair corrupted first cluster it is required to  call  fsck.fat
           with non-zero NUM value.

       -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.

       -p  Same as -a, for compatibility with other *fsck.

       -r  Interactively repair the filesystem.  The user is asked for advice whenever  there  is
           more  than  one  approach  to  fix an inconsistency.  This is the default mode and the
           option is only retained for backwards compatibility.

       -S  Consider short (8.3) file names with spaces in the middle to be invalid, like previous
           versions  of  this  program  did.   While such file names are not forbidden by the FAT
           specification, and were never treated as errors  by  Microsoft  file  system  checking
           tools,  many  DOS  programs  are  unable  to handle files with such names.  Using this
           option can make them accessible to these programs.

           Short file names which start with a space are considered invalid  regardless  of  this
           option's setting.

           Previous versions of this program exceptionally treated EA DATA. SF and WP ROOT. SF as
           valid short names; using this option does not preserve that exception.

       -t  Mark unreadable clusters as bad.

       -u PATH
           Try to undelete the specified file.  fsck.fat tries to allocate a chain of  contiguous
           unallocated  clusters  beginning  with  the start cluster of the undeleted file.  This
           option can be given more than once.

       -U  Consider lowercase  volume  and  boot  label  as  invalid  and  allow  only  uppercase
           characters.   Such  labels are forbidden by the FAT specification, but they are widely
           used by Linux tools.  Moreover MS-DOS and Windows systems do not have problems to read
           them.   Therefore  volume  and  boot  labels  with lowercase characters are by default
           permitted.

       -v  Verbose mode.  Generates slightly more output.

       -V  Perform a verification pass.  The filesystem 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.

       --variant TYPE
           Create a filesystem of variant TYPE.  Acceptable values are standard and atari (in any
           combination of upper/lower case).  See above under DESCRIPTION for the differences.

       -w  Write changes to disk immediately.

       -y  Same as -a (automatically repair filesystem) for compatibility with other fsck tools.

       --help
           Display help message describing usage and options then exit.

EXIT STATUS

       0   No recoverable errors have been detected.

       1   Recoverable  errors  have  been  detected  or  fsck.fat  has  discovered  an  internal
           inconsistency.

       2   Usage error.  fsck.fat did not access the filesystem.

FILES

       fsck0000.rec, fsck0001.rec, ...
           When  recovering from a corrupted filesystem, fsck.fat dumps recovered data into files
           named fsckNNNN.rec in the top level directory of the filesystem.

BUGS

       ·   Does not remove entirely empty directories.

       ·   Should give more diagnostic messages.

       ·   Undeleting files should use a more sophisticated algorithm.

SEE ALSO

       fatlabel(8), mkfs.fat(8)

HOMEPAGE

       The   home   for    the    dosfstools    project    is    its    GitHub    project    page
       ⟨https://github.com/dosfstools/dosfstools⟩.

AUTHORS

       dosfstools  were  written by Werner Almesberger ⟨werner.almesberger@lrc.di.epfl.ch⟩, Roman
       Hodek  ⟨Roman.Hodek@informatik.uni-erlangen.de⟩,  and  others.   Current  maintainers  are
       Andreas Bombe ⟨aeb@debian.org⟩ and Pali Rohár ⟨pali.rohar@gmail.com⟩.