e2fsck manpage

Search topic Section

E2FSCK(8)		    System Manager's Manual		     E2FSCK(8)

       e2fsck - check a Linux ext2/ext3/ext4 file system

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

       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 a block device (e.g., /dev/sdc1) or file containing the file

       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.

       If  e2fsck  is run in interactive mode (meaning that none of -y, -n, or
       -p are specified), the program will ask the user to  fix	 each  problem
       found  in  the  filesystem.   A response of 'y' will fix the error; 'n'
       will leave the error unfixed; and 'a' will fix the problem and all sub-
       sequent	 problems;  pressing  Enter  will  proceed  with  the  default
       response, which is printed before the question mark.  Pressing Control-
       C terminates e2fsck immediately.

       -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

	      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

       -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:

			  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.

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

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

			  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.

			  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.

			  Do not offer to optimize the extent tree  by	elimi-
			  nating unnecessary width or depth.

			  Use this many KiB of memory to pre-fetch metadata in
			  the hopes of reducing e2fsck runtime.	  By  default,
			  this	is  set to the size of two block groups' inode
			  tables (typically 4MiB on a  regular	ext4  filesys-
			  tem);	 if  this  amount is more than 1/50th of total
			  physical memory, readahead is disabled.  Set this to
			  zero to disable readahead entirely.

			  Convert block-mapped files to extent-mapped files.

			  Only	fix  damaged  metadata;	 do not optimize htree
			  directories or compress extent trees.	  This	option
			  is  incompatible  with  the  -D  and	-E bmap2extent

       -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

       -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

       -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.

       -z undo_file
	      Before overwriting a file system block, write the	 old  contents
	      of  the  block to an undo file.  This undo file can be used with
	      e2undo(8) to restore the old contents of the file system	should
	      something	 go  wrong.   If  the  empty  string  is passed as the
	      undo_file argument, the undo file will  be  written  to  a  file
	      named  e2fsck-device.e2undo  in  the directory specified via the
	      E2FSPROGS_UNDO_DIR environment variable.

	      WARNING: The undo file cannot be used to recover from a power or
	      system crash.

       The  exit  code	returned  by e2fsck is the sum of the following condi-
	    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

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

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

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

       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.

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

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

E2fsprogs version 1.43.5	  August 2017			     E2FSCK(8)