e2fsck(8) - phpMan

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E2FSCK(8)                                                            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 indicates 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 filesystems.  The only
       exception is if the -n option is specified, and -c, -l, or -L options are not spec-
       ified.    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 provided for back-
              wards compatibility only; it is suggested that people use -p option whenever
              possible.

       -b superblock
              Instead of using the normal superblock, use an alternative superblock speci-
              fied  by  superblock.   This  option  is  normally  used  when  the  primary
              superblock  has  been  corrupted.   The location of the backup superblock is
              dependent on the filesystem's blocksize.  For  filesystems  with  1k  block-
              sizes,  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 specifies 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  different  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  particular  blocksize.   If  the superblock is not found,
              e2fsck will terminate 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  directory.  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  programs  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  sup-
              pressed  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 sup-
              ports directory indexing,  or by sorting  and  compressing  directories  for
              smaller  directories,  or  for filesystems using traditional linear directo-
              ries.

              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 separated, 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.

                   fragcheck
                          During pass 1, print a  detailed  report  of  any  discontiguous
                          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  recog-
                          nise  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  exacly 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 block-
              size of the filesystem 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 ques-
              tions.  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 logically
              or'ed into the exit code.  (See the EXIT CODE section.)  This option is nor-
              mally  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 backwards  compati-
              bility.

       -t     Print  timing  statistics  for  e2fsck.  If this option is used twice, addi-
              tional 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 conditions:
            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  transcript  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 AT mit.edu>.

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



E2fsprogs version 1.41.12          May 2010                          E2FSCK(8)

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