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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_op-
       tions ] 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 su-
	      perblock specified 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	block-
	      size.   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  su-
	      perblocks	 were created.	 The -b	option to mke2fs, which	speci-
	      fies 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 su-
	      perblock	 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 in-
	      ode 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  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  re-
	      quires 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  in-
	      dexed,  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.

       -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 de-
	      scription	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 op-
	      tion.)

       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 in-
       ode  or	inodes	seems to be giving e2fsck trouble, try running the de-
       bugfs(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 com-
       mand 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 1.41.14	 December 2010			     E2FSCK(8)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT CODE | SIGNALS | REPORTING BUGS | AUTHOR | SEE ALSO

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