NAME
       fsck - check and repair a Linux file system

SYNOPSIS
       fsck [ -sAVRTNP ] [ -C [ fd ] ] [ -t fstype ] [filesys ... ] [--] [ fs-
       specific-options ]

DESCRIPTION
       fsck is used to check and optionally repair one or more Linux file sys-
       tems.   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).  Nor-
       mally, the fsck program will try to  handle  filesystems  on  different
       physical  disk  drives  in  parallel to reduce the total amount of time
       needed to check all of the filesystems.

       If no filesystems are specified on the command line, and the -A  option
       is  not  specified,  fsck  will  default  to  checking  filesystems  in
       /etc/fstab serially.  This is equivalent to the -As options.

       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
            32   - Fsck canceled by user request
            128  - Shared library error
       The exit code returned when multiple file systems are  checked  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 directories listed in  the  PATH  environment  variable.
       Please  see  the  file system-specific checker manual pages for further
       details.

OPTIONS
       -s     Serialize fsck operations.  This is  a  good  idea  if  you  are
              checking  multiple filesystems and the checkers are in an inter-
              active 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 parameter  is  a  comma-separated  list  of
              filesystems  and  options specifiers.  All of the filesystems in
              this comma-separated list may be prefixed by a negation 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.   If an
              options specifier is present, then only filesystems  which  con-
              tain  fs-option  in their mount options field of /etc/fstab will
              be checked.  If the options specifier is prefixed by a  negation
              operator, then only those filesystems that do not have fs-option
              in their mount options field of /etc/fstab will be checked.

              For example, if opts=ro appears in fslist, then only filesystems
              listed in /etc/fstab with the ro option 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  searching  for
              filesys  in  the  /etc/fstab  file  and  using the corresponding
              entry.  If the type can not be deduced, and there is only a sin-
              gle  filesystem given as an argument to the -t option, fsck will
              use the specified filesystem type.  If this type is  not  avail-
              able,  then  the  default  file  system type (currently ext2) is
              used.

       -A     Walk through the /etc/fstab file and try to check all file  sys-
              tems in one run.  This option is typically used from the /etc/rc
              system initialization 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 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 files is to set
              the root filesystem to have a fs_passno value of 1  and  to  set
              all other filesystems to have a fs_passno value of 2.  This will
              allow fsck to automatically run filesystem checkers in  parallel
              if  it  is  advantageous  to do so.  System administrators might
              choose not to use this configuration if they need to avoid  mul-
              tiple  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 [  fd  ]
              Display  completion/progress  bars for those filesystem checkers
              (currently only for ext2 and ext3) which  support  them.    Fsck
              will  manage  the  filesystem  checkers so that only one of them
              will display a progress bar at a time.  GUI front-ends may spec-
              ify  a file descriptor fd, in which case the progress bar infor-
              mation will be sent to that file descriptor.

       -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  repar-
              tition  the  root  filesystem  to be small and compact (which is
              really the right solution).

       -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 com-
              mands that are executed.

       fs-specific-options
              Options 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 arbitrarily com-
              plicated 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  com-
              plicated  option  and  arguments,  and  it  doesn't  do what you
              expect, don't bother reporting it as a bug.  You're almost  cer-
              tainly doing something that you shouldn't be doing with fsck.

       Options  to  different filesystem-specific fsck's are not standardized.
       If in doubt, please consult the man pages  of  the  filesystem-specific
       checker.   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 compatibility only.  This option is mapped to e2fsck's
              -p  option  which is safe to use, unlike the -a option that some
              file system checkers support.

       -n     For some filesystem-specific checkers, the -n option will  cause
              the fs-specific fsck to avoid attempting to repair any problems,
              but simply report such problems to stdout.  This is however  not
              true  for  all  filesystem-specific  checkers.   In  particular,
              fsck.reiserfs(8) will not report any corruption  if  given  this
              option.  fsck.minix(8) does not support the -n option at all.

       -r     Interactively  repair  the  filesystem  (ask for confirmations).
              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.

       -y     For  some filesystem-specific checkers, the -y option will cause
              the fs-specific fsck to  always  attempt  to  fix  any  detected
              filesystem corruption automatically.  Sometimes an expert may be
              able to do better driving the fsck manually.  Note that not  all
              filesystem-specific checkers implement this option.  In particu-
              lar fsck.minix(8) and fsck.cramfs(8) does  not  support  the  -y
              option as of this writing.

AUTHOR
       Theodore Ts'o (tytso@mit.edu)

FILES
       /etc/fstab.

ENVIRONMENT VARIABLES
       The  fsck  program's  behavior is affected by the following environment
       variables:

       FSCK_FORCE_ALL_PARALLEL
              If this environment variable is set, fsck will  attempt  to  run
              all  of  the  specified  filesystems  in parallel, regardless of
              whether the filesystems appear to be on the same device.   (This
              is  useful  for RAID systems or high-end storage systems such as
              those sold by companies such as IBM or EMC.)

       FSCK_MAX_INST
              This environment variable will limit the maximum number of  file
              system  checkers  that  can be running at one time.  This allows
              configurations which have a large number of disks to avoid  fsck
              starting  too  many  file  system  checkers at once, which might
              overload CPU and memory resources available on the  system.   If
              this value is zero, then an unlimited number of processes can be
              spawned.  This is currently the default, but future versions  of
              fsck may attempt to automatically determine how many file system
              checks can be run based on gathering accounting  data  from  the
              operating system.

       PATH   The PATH environment variable is used to find file system check-
              ers.  A set of system directories  are  searched  first:  /sbin,
              /sbin/fs.d, /sbin/fs, /etc/fs, and /etc.  Then the set of direc-
              tories found in the PATH environment are searched.

       FSTAB_FILE
              This environment variable allows  the  system  administrator  to
              override  the  standard  location of the /etc/fstab file.  It is
              also useful for developers who are testing fsck.

SEE ALSO
       fstab(5), mkfs(8), fsck.ext2(8) or fsck.ext3(8)  or  e2fsck(8),  cramf-
       sck(8),   fsck.minix(8),   fsck.msdos(8),   fsck.jfs(8),   fsck.nfs(8),
       fsck.vfat(8), fsck.xfs(8), fsck.xiafs(8), reiserfsck(8).

E2fsprogs version 1.39             May 2006                            FSCK(8)