E2FSCK(8)                   System Manager's Manual                  E2FSCK(8)
NAME
       e2fsck - check a Linux ext2/ext3/ext4 file system

SYNOPSIS
       e2fsck  [  -pacnyrdfkvtDFV ] [ -b superblock ] [ -B blocksize ] [ -l|-L
       bad_blocks_file  ]  [  -C  fd  ]  [  -j   external-journal   ]   [   -E
       extended_options ] device

DESCRIPTION
       e2fsck is used to check the ext2/ext3/ext4 family of file systems.  For
       ext3 and ext4 filesystems that use a journal, if the  system  has  been
       shut  down  uncleanly without any errors, normally, after replaying the
       committed transactions  in the  journal,  the  file  system  should  be
       marked  as clean.   Hence, for filesystems that use journalling, e2fsck
       will normally replay the journal and exit, unless its superblock  indi-
       cates that further checking is required.

       device  is  the  device  file  where  the  filesystem  is  stored (e.g.
       /dev/hdc1).

       Note that in general it is not safe to run e2fsck on  mounted  filesys-
       tems.  The only exception is if the -n option is specified, and -c, -l,
       or -L options are not specified.   However, even if it is  safe  to  do
       so,  the  results  printed by e2fsck are not valid if the filesystem is
       mounted.   If e2fsck asks whether or not you should check a  filesystem
       which  is mounted, the only correct answer is ``no''.  Only experts who
       really know what they are doing should consider answering this question
       in any other way.

OPTIONS
       -a     This  option  does  the same thing as the -p option.  It is pro-
              vided for backwards compatibility only;  it  is  suggested  that
              people use -p option whenever possible.

       -b superblock
              Instead  of  using  the  normal  superblock,  use an alternative
              superblock specified by superblock.   This  option  is  normally
              used  when the primary superblock has been corrupted.  The loca-
              tion of the backup superblock is dependent on  the  filesystem's
              blocksize.    For  filesystems  with  1k  blocksizes,  a  backup
              superblock can be found at block 8193; for filesystems  with  2k
              blocksizes,  at  block  16384;  and  for 4k blocksizes, at block
              32768.

              Additional backup superblocks can be  determined  by  using  the
              mke2fs  program  using  the  -n  option  to  print out where the
              superblocks were created.   The -b option to mke2fs, which spec-
              ifies blocksize of the filesystem must be specified in order for
              the superblock locations that are printed out to be accurate.

              If an alternative superblock is specified and the filesystem  is
              not  opened  read-only,  e2fsck  will make sure that the primary
              superblock is  updated  appropriately  upon  completion  of  the
              filesystem check.

       -B blocksize
              Normally,  e2fsck will search for the superblock at various dif-
              ferent block sizes in an attempt to find the  appropriate  block
              size.   This  search  can  be fooled in some cases.  This option
              forces e2fsck to only try locating the superblock at a  particu-
              lar blocksize.  If the superblock is not found, e2fsck will ter-
              minate with a fatal error.

       -c     This option causes e2fsck to use badblocks(8) program  to  do  a
              read-only  scan  of  the device in order to find any bad blocks.
              If any bad blocks are found, they are added  to  the  bad  block
              inode  to  prevent them from being allocated to a file or direc-
              tory.  If this option is specified twice,  then  the  bad  block
              scan will be done using a non-destructive read-write test.

       -C fd  This option causes e2fsck to write completion information to the
              specified file descriptor so that the progress of the filesystem
              check  can  be monitored.  This option is typically used by pro-
              grams which are running e2fsck.  If the file  descriptor  number
              is  negative, then absolute value of the file descriptor will be
              used, and the progress information will be suppressed initially.
              It  can later be enabled by sending the e2fsck process a SIGUSR1
              signal.  If the file descriptor  specified  is  0,  e2fsck  will
              print  a  completion  bar  as  it goes about its business.  This
              requires that e2fsck is running on a video console or terminal.

       -d     Print  debugging  output  (useless  unless  you  are   debugging
              e2fsck).

       -D     Optimize  directories  in filesystem.  This option causes e2fsck
              to try to optimize all directories, either by reindexing them if
              the  filesystem  supports directory indexing,  or by sorting and
              compressing directories for smaller directories, or for filesys-
              tems using traditional linear directories.

              Even  without the -D option, e2fsck may sometimes optimize a few
              directories --- for example, if directory  indexing  is  enabled
              and  a  directory  is  not  indexed and would benefit from being
              indexed, or if the index structures are corrupted and need to be
              rebuilt.  The -D option forces all directories in the filesystem
              to be optimized.  This can sometimes make them a little  smaller
              and  slightly  faster  to  search,  but  in practice, you should
              rarely need to use this option.

              The -D option will detect directory entries with duplicate names
              in  a  single  directory, which e2fsck normally does not enforce
              for performance reasons.

       -E extended_options
              Set e2fsck extended options.  Extended options are  comma  sepa-
              rated,  and  may  take  an argument using the equals ('=') sign.
              The following options are supported:

                   ea_ver=extended_attribute_version
                          Set the version of  the  extended  attribute  blocks
                          which   e2fsck   will  require  while  checking  the
                          filesystem.  The version number may be 1 or 2.   The
                          default extended attribute version format is 2.

                   journal_only
                          Only replay the journal if required, but do not per-
                          form any further checks or repairs.

                   fragcheck
                          During pass 1, print a detailed report of  any  dis-
                          contiguous blocks for files in the filesystem.

                   discard
                          Attempt  to  discard  free  blocks  and unused inode
                          blocks after the full filesystem  check  (discarding
                          blocks is useful on solid state devices and sparse /
                          thin-provisioned storage). Note that discard is done
                          in  pass  5  AFTER  the  filesystem  has  been fully
                          checked and only if it does not contain recognizable
                          errors.  However  there  might be cases where e2fsck
                          does not fully recognize a problem and hence in this
                          case this option may prevent you from further manual
                          data recovery.

                   nodiscard
                          Do not attempt to discard  free  blocks  and  unused
                          inode blocks. This option is exactly the opposite of
                          discard option. This is set as default.

       -f     Force checking even if the file system seems clean.

       -F     Flush the filesystem device's buffer  caches  before  beginning.
              Only really useful for doing e2fsck time trials.

       -j external-journal
              Set  the pathname where the external-journal for this filesystem
              can be found.

       -k     When combined with the -c option, any existing bad blocks in the
              bad  blocks  list are preserved, and any new bad blocks found by
              running badblocks(8) will be added to the  existing  bad  blocks
              list.

       -l filename
              Add  the  block numbers listed in the file specified by filename
              to the list of bad blocks.  The format of this file is the  same
              as the one generated by the badblocks(8) program.  Note that the
              block numbers are based on  the  blocksize  of  the  filesystem.
              Hence,  badblocks(8) must be given the blocksize of the filesys-
              tem in order to obtain correct results.  As a result, it is much
              simpler  and safer to use the -c option to e2fsck, since it will
              assure that the correct parameters are passed to  the  badblocks
              program.

       -L filename
              Set  the  bad  blocks list to be the list of blocks specified by
              filename.  (This option is the same as the -l option, except the
              bad  blocks list is cleared before the blocks listed in the file
              are added to the bad blocks list.)

       -n     Open the filesystem read-only, and assume an answer of  `no'  to
              all  questions.   Allows  e2fsck  to  be used non-interactively.
              This option may not be specified at the same time as the  -p  or
              -y options.

       -p     Automatically  repair  ("preen")  the  file system.  This option
              will cause e2fsck to automatically fix any  filesystem  problems
              that  can be safely fixed without human intervention.  If e2fsck
              discovers a problem which may require the  system  administrator
              to  take  additional  corrective  action,  e2fsck  will  print a
              description of the problem and then exit with the value 4  logi-
              cally  or'ed  into  the exit code.  (See the EXIT CODE section.)
              This option is normally used by the system's boot  scripts.   It
              may not be specified at the same time as the -n or -y options.

       -r     This  option  does nothing at all; it is provided only for back-
              wards compatibility.

       -t     Print timing statistics for e2fsck.   If  this  option  is  used
              twice,  additional  timing  statistics  are printed on a pass by
              pass basis.

       -v     Verbose mode.

       -V     Print version information and exit.

       -y     Assume an answer of `yes' to all questions; allows e2fsck to  be
              used non-interactively.  This option may not be specified at the
              same time as the -n or -p options.

EXIT CODE
       The exit code returned by e2fsck is the sum  of  the  following  condi-
       tions:
            0    - No errors
            1    - File system errors corrected
            2    - File system errors corrected, system should
                   be rebooted
            4    - File system errors left uncorrected
            8    - Operational error
            16   - Usage or syntax error
            32   - E2fsck canceled by user request
            128  - Shared library error

SIGNALS
       The following signals have the following effect when sent to e2fsck.

       SIGUSR1
              This  signal  causes e2fsck to start displaying a completion bar
              or emitting progress information.  (See  discussion  of  the  -C
              option.)

       SIGUSR2
              This signal causes e2fsck to stop displaying a completion bar or
              emitting progress information.

REPORTING BUGS
       Almost any piece of software will have bugs.  If you manage to  find  a
       filesystem  which  causes e2fsck to crash, or which e2fsck is unable to
       repair, please report it to the author.

       Please include as much information as  possible  in  your  bug  report.
       Ideally,  include a complete transcript of the e2fsck run, so I can see
       exactly what error messages are displayed.   (Make  sure  the  messages
       printed by e2fsck are in English; if your system has been configured so
       that e2fsck's messages have  been  translated  into  another  language,
       please  set  the the LC_ALL environment variable to C so that the tran-
       script of e2fsck's output will  be  useful  to  me.)   If  you  have  a
       writable  filesystem  where the transcript can be stored, the script(1)
       program is a handy way to save the output of e2fsck to a file.

       It is also useful to send the output of  dumpe2fs(8).   If  a  specific
       inode  or  inodes  seems  to  be giving e2fsck trouble, try running the
       debugfs(8) command and send the output of the stat(1u) command  run  on
       the  relevant  inode(s).  If the inode is a directory, the debugfs dump
       command will allow you to extract the contents of the directory  inode,
       which  can  sent  to me after being first run through uuencode(1).  The
       most useful data you can send to help reproduce the bug is a compressed
       raw  image dump of the filesystem, generated using e2image(8).  See the
       e2image(8) man page for more details.

       Always include the full version string which e2fsck displays when it is
       run, so I know which version you are running.

AUTHOR
       This version of e2fsck was written by Theodore Ts'o <tytso@mit.edu>.

SEE ALSO
       e2fsck.conf(5),   badblocks(8),  dumpe2fs(8),  debugfs(8),  e2image(8),
       mke2fs(8), tune2fs(8)

E2fsprogs version 1.42.13          May 2015                          E2FSCK(8)