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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 exter-
       nal-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 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 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 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 filesystems using traditional linear directories.

              Even  without  the -D option, e2fsck may sometimes optimize a few directories --- for example, if direc-
              tory 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 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 discontiguous blocks for files in the filesys-
                          tem.

                   discard
                          Attempt to discard free blocks and unused inode blocks after the full filesystem check (dis-
                          carding 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 recognise 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 exacly 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 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 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 <tytsoATmit.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)