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 speci‐
       fied, 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  ques‐
       tion in any other way.

OPTIONS
       -a     This  option does the same thing as the -p option.  It is provided 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  nor‐
	      mally  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 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 specifies blocksize of the filesystem must be  speci‐
	      fied 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 appropri‐
	      ate  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-destruc‐
	      tive 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 infor‐
	      mation 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  rein‐
	      dexing  them  if	the filesystem supports directory indexing,  or by sorting and compressing directories for smaller
	      directories, or for filesystems 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 cor‐
	      rupted 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  filesys‐
			  tem.	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 perform any further checks or repairs.

		   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 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  block‐
	      size  of	the filesystem.  Hence, badblocks(8) must be given the blocksize of the filesystem in order to obtain cor‐
	      rect 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-interac‐
	      tively.  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  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 backwards 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 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 .

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



E2fsprogs version 1.42.5				     July 2012							 E2FSCK(8)