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_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 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 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 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 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 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 nega-
	      tive,  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 comple-
	      tion 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 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 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 fol-
	      lowing 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.

       -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 run-
	      ning 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 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 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  addi-
	      tional  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 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)  pro-
       gram 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 1.41.11					    March 2010								 E2FSCK(8)