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       fsck - check and repair a Linux file system


       fsck [-sAVRTMNP] [-C [fd]] [-t fstype] [filesys...]  [--] [fs-specific-


       fsck is used to check and optionally repair  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).
       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 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


       -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 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
              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 file system type (currently ext2) is

       -A     Walk  through  the  /etc/fstab  file  and  try to check all file
              systems 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
              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  file system specific checker. Therefore non-
              existing devices may cause  the  system  to  enter  file  system
              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 file system type auto

       -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
              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 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.

              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

              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 option and arguments, and it  doesn’t  do  what  you
              expect,  dont  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 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
              particular fsck.minix(8) and fsck.cramfs(8) does not support the
              -y option as of this writing.


       Theodore Ts’o (


       The blkid command is part of the util-linux-ng package and is available




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

              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.)

              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
              checkers.   A  set  of  system  directories  are searched first:
              /sbin, /sbin/fs.d, /sbin/fs, /etc/fs, and /etc.  Then the set of
              directories found in the PATH environment are searched.

              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.


       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), fsck.xiafs(8), reiserfsck(8).