Provided by: util-linux_2.27.1-6ubuntu2_i386 bug


       fsck - check and repair a Linux filesystem


       fsck  [-lsAVRTMNP] [-r [fd]] [-C [fd]] [-t fstype] [filesystem...] [--]


       fsck is  used  to  check  and  optionally  repair  one  or  more  Linux
       filesystems.    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).  Normally, 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 them.

       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      Filesystem errors corrected
              2      System should be rebooted
              4      Filesystem errors left uncorrected
              8      Operational error
              16     Usage or syntax error
              32     Checking canceled by user request
              128    Shared-library error

       The exit code returned when multiple filesystems  are  checked  is  the
       bit-wise OR of the exit codes for each filesystem that is checked.

       In  actuality,  fsck  is  simply a front-end for the various filesystem
       checkers (fsck.fstype) available under Linux.  The  filesystem-specific
       checker  is  searched for in the PATH environment variable. If the PATH
       is undefined then fallback to "/sbin".

       Please see the filesystem-specific checker  manual  pages  for  further


       -l     Create       an      exclusive      flock(2)      lock      file
              (/run/fsck/<diskname>.lock) for whole-disk device.  This  option
              can  be used with one device only (this means that -A and -l are
              mutually exclusive).   This  option  is  recommended  when  more
              fsck(8)  instances are executed in the same time.  The option is
              ignored when used  for  multiple  devices  or  for  non-rotating
              disks.   fsck  does not lock underlying devices when executed to
              check stacked devices (e.g. MD or DM)  –  this  feature  is  not
              implemented yet.

       -r [fd]
              Report  certain  statistics  for  each  fsck  when it completes.
              These statistics include the exit status, the  maximum  run  set
              size (in kilobytes), the elapsed all-clock time and the user and
              system CPU time used by the fsck run.  For example:

              /dev/sda1: status 0, rss 92828, real  4.002804,  user  2.677592,
              sys 0.86186

              GUI  front-ends  may specify a file descriptor fd, in which case
              the  progress  bar  information  will  be  sent  to  that   file
              descriptor in a machine parseable format.  For example:

              /dev/sda1 0 92828 4.002804 2.677592 0.86186

       -s     Serialize  fsck  operations.   This  is  a  good idea if you are
              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

       -t fslist
              Specifies  the type(s) of filesystem 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 none of the filesystems in
              fslist is prefixed by  a  negation  operator,  then  only  those
              listed filesystems 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
              contain 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

              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
              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 filesystem type (currently ext2) is

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

              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.

              fsck  does  not  check stacked devices (RAIDs, dm-crypt, ...) in
              parallel   with   any   other    device.     See    below    for
              FSCK_FORCE_ALL_PARALLEL setting.  The /sys filesystem is used to
              detemine dependencies between devices.

              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
              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.

              fsck normally does not check whether the device actually  exists
              before  calling  a  filesystem specific checker.  Therefore non-
              existing devices may cause the system to enter filesystem repair
              mode  during  boot  if the filesystem specific checker returns a
              fatal error.  The /etc/fstab mount option nofail may be used  to
              have  fsck  skip  non-existing  devices.   fsck  also skips non-
              existing devices that have the special filesystem type auto.

       -C [fd]
              Display completion/progress bars for those  filesystem  checkers
              (currently  only  for  ext[234])  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 specify a
              file descriptor fd, in which case the progress  bar  information
              will be sent to that file descriptor.

       -M     Do  not  check  mounted filesystems and return an exit code of 0
              for mounted filesystems.

       -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 solution).

       -R     When checking all filesystems with the -A flag,  skip  the  root
              filesystem.   (This  is  useful  in case the root filesystem has
              already been mounted read-write.)

       -T     Don't show the title on startup.

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

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

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

              Please note that  fsck  is  not  designed  to  pass  arbitrarily
              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
              complicated options and arguments, and it doesn't  do  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.

       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 filesystem checkers:

       -a     Automatically  repair  the filesystem without any questions (use
              this option with caution).  Note that e2fsck(8) supports -a  for
              backward  compatibility only.  This option is mapped to e2fsck's
              -p option which is safe to use, unlike the -a option  that  some
              filesystem 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 backward
              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
              particular  fsck.minix(8)  and fsck.cramfs(8) do not support the
              -y option as of this writing.




       The fsck program's behavior is affected by  the  following  environment

              If  this environment variable is set, fsck will attempt to check
              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.)  Note that the
              fs_passno value is still used.

              This environment variable  will  limit  the  maximum  number  of
              filesystem  checkers  that  can  be  running  at one time.  This
              allows configurations which have a  large  number  of  disks  to
              avoid  fsck starting too many filesystem 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
              filesystem checks can be run based on gathering accounting  data
              from the operating system.

       PATH   The  PATH  environment  variable  is  used  to  find  filesystem

              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.

              enables libblkid debug output.

              enables libmount debug output.


       fstab(5), mkfs(8), fsck.ext2(8) or fsck.ext3(8) or e2fsck(8),
       cramfsck(8), fsck.minix(8), fsck.msdos(8), fsck.jfs(8), fsck.nfs(8),
       fsck.vfat(8), fsck.xfs(8), reiserfsck(8).


       Theodore Ts'o ⟨


       The fsck command is part of the util-linux  package  and  is  available
       from  Linux  Kernel Archive ⟨