fsck - check and repair a Linux file system


SYNOPSIS

       fsck  [  -sACVRTNP  ] [ -t fstype ] filesys [ ... ] [--] [
       fsck-options ]


DESCRIPTION

       fsck is used to check and optionally repair a one or  more
       Linux  file  systems.   filesys can be a device name (e.g.
       /dev/hdc1, /dev/sdb2),  a  mount  point  (e.g.   /,  /usr,
       /home),   or   an  ext2  label  or  UUID  specifier  (e.g.
       UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd or  LABEL=root).
       The  fsck program will try to run filesystems on different
       physical disk drives in parallel to  reduce  total  amount
       time to check all of the filesystems.

       The exit code returned by fsck is the sum of the following
       conditions:
            0    - No errors
            1    - File system errors corrected
            2    - System should be rebooted
            4    - File system errors left uncorrected
            8    - Operational error
            16   - Usage or syntax error
            128  - Shared library error
       The exit code returned when all file systems  are  checked
       using  the  -A option is the bit-wise OR of the exit codes
       for each file system that is checked.

       In actuality, fsck is simply a front-end for  the  various
       file  system checkers (fsck.fstype) available under Linux.
       The file system-specific checker is searched for in  /sbin
       first, then in /etc/fs and /etc, and finally in the direc­
       tories listed in the PATH  environment  variable.   Please
       see the file system-specific checker manual pages for fur­
       ther details.


OPTIONS

       -s     Serialize fsck operations.  This is a good idea  if
              you  checking multiple filesystems and the checkers
              are in an interactive mode.  (Note: e2fsck(8)  runs
              in   an  interactive  mode  by  default.   To  make
              e2fsck(8) run in a non-interactive mode,  you  must
              either specify the -p or -a option, if you wish for
              errors to be corrected  automatically,  or  the  -n
              option if you do not.)

       -t fslist
              Specifies the type(s) of file system to be checked.
              When the -A flag  is  specified,  only  filesystems
              that  match fslist are checked.  The fslist parame­
              ter is a comma-separated list  of  filesystems  and
              options specifiers.  All of the filesystems in this

              operator  'no'  or  '!',  which  requests that only
              those filesystems not  listed  in  fslist  will  be
              checked.   If  all of the filesystems in fslist are
              not prefixed by  a  negation  operator,  then  only
              those filesystems listed in fslist will be checked.

              Options specifiers may be  included  in  the  comma
              separated   fslist.   They  must  have  the  format
              opts=fs-option, and may be prefixed by  a  negation
              operator.  If an options specifier is present, then
              only filesystems whose /etc/fstab entry do  (or  do
              not,  if  the  options  specifier was prefixed by a
              negation  operator)  contain  fs-option  in   their
              options  field  of  the  /etc/fstab  file  will  be
              checked.

              For compatibility with Mandrake distributions whose
              boot  scripts depend upon an unauthorized UI change
              to the fsck program, if a filesystem type  of  loop
              is  found  in fslist, it is treated as if opts=loop
              were specified as an argument to the -t option.

              Normally, the filesystem type is deduced by search­
              ing  for  filesys  in the /etc/fstab file and using
              the corresponding entry.  If the type  can  not  be
              deduced,  and  there  is  only  a single filesystem
              given as an argument to the -t  option,  fsck  will
              use the specified filesystem type.  If this type is
              not available, then the default  file  system  type
              (currently ext2) is used.

       -A     Walk  through  the /etc/fstab file and try to check
              all file systems in one run.  This option is  typi­
              cally  used  from  the /etc/rc system initalization
              file, instead of multiple commands for  checking  a
              single file system.

              The  root  filesystem  will be checked first unless
              the -P option  is  specified  (see  below).   After
              that,  filesystems  will  be  checked  in the order
              specified by the fs_passno (the sixth) field in the
              /etc/fstab  file.   Filesystems  with  a  fs_passno
              value of 0 are skipped and are not checked at  all.
              Filesystems  with a fs_passno value of greater than
              zero will be checked  in  order,  with  filesystems
              with  filesystems  with the lowest fs_passno number
              being  checked  first.   If  there   are   multiple
              filesystems  with  the  same pass number, fsck will
              attempt to check them in parallel, although it will
              avoid  running  multiple  filesystem  checks on the
              same physical disk.

              Hence, a very common  configuration  in  /etc/fstab

              fs_passno value of 1 and to set all filesystems  to
              have  a fs_passno value of 2.  This will allow fsck
              to automatically run filesystem checkers in  paral­
              lel  if it is advantageous to do so.  System admin­
              istrators might choose not to use  this  configura­
              tion  if  they  need  to  avoid multiple filesystem
              checks running in parallel for some reason ---  for
              example,  if  the  machine  in question is short on
              memory so that excessive paging is a concern.

       -C     Display completion/progress bars for those filesys­
              tems  checkers (currently only for ext2) which sup­
              port them.   Fsck will manage the filesystem check­
              ers  so  that  only  one  of  them  will  display a
              progress bar at a time.

       -N     Don't execute, just show what would be done.

       -P     When the -A flag is set, check the root  filesystem
              in  parallel  with  the other filesystems.  This is
              not the safest thing in the world to do,  since  if
              the  root  filesystem  is  in doubt things like the
              e2fsck(8)  executable  might  be  corrupted!   This
              option  is  mainly provided for those sysadmins who
              don't want to repartition the root filesystem to be
              small  and compact (which is really the right solu­
              tion).

       -R     When checking all file systems with  the  -A  flag,
              skip  the  root  file  system (in case it's already
              mounted read-write).

       -T     Don't show the title on startup.

       -V     Produce verbose output, including all file  system-
              specific commands that are executed.

       fsck-options
              Options  which which are not understood by fsck are
              passed to the filesystem-specific  checker.   These
              arguments  must  not take arguments, as there is no
              way for fsck to be able  to  properly  guess  which
              arguments take options and which don't.

              Options  and  arguments  which  follow  the  -- are
              treated  as  file  system-specific  options  to  be
              passed to the file system-specific checker.

              Please note that fsck is not designed to pass arbi­
              trarily complicated options to  filesystem-specific
              checkers.   If  you're doing something complicated,
              please just execute the filesystem-specific checker
              directly.    If   you   pass   fsck  some  horribly

              what  you  expect,  don't  bother reporting it as a
              bug.  You're almost certainly doing something  that
              you shouldn't be doing with fsck.

       Currently,  standardized  file system-specific options are
       somewhat in flux.  Although not guaranteed, the  following
       options are supported by most file system checkers:

       -a     Automatically  repair  the  file system without any
              questions (use this  option  with  caution).   Note
              that  e2fsck(8)  supports -a for backwards compati­
              bility only.  This option is mapped to e2fsck's  -p
              option  which  is safe to use, unlike the -a option
              that most file system checkers support.

       -r     Interactively repair the filesystem (ask  for  con­
              firmations).   Note:  It is generally a bad idea to
              use this option if multiple fsck's are being run in
              parallel.   Also note that this is e2fsck's default
              behavior; it supports  this  option  for  backwards
              compatibility reasons only.


AUTHOR

       Theodore Ts'o (tytso@mit.edu)

       The  manual  page was shamelessly adapted from David Engel
       and Fred van Kempen's  generic  fsck  front  end  program,
       which  was  in  turn  shamelessly adapted from Remy Card's
       version for the ext2 file system.


FILES

       /etc/fstab.


SEE ALSO

       fstab(5),   mkfs(8),   fsck.minix(8),   fsck.ext2(8)    or
       e2fsck(8), fsck.xiafs(8).


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