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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	 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.

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

       -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 1.41.12	   May 2010			     E2FSCK(8)
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