e2fsck(8) — Linux manual page


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

NAME         top

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

SYNOPSIS         top

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

DESCRIPTION         top

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

       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.

       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
       subsequent problems; pressing Enter will proceed with the default
       response, which is printed before the question mark.  Pressing
       Control-C terminates e2fsck immediately.

OPTIONS         top

       -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 backup superblocks is dependent on the
              filesystem's blocksize, the number of blocks per group, and
              features such as sparse_super.

              Additional backup superblocks can be determined by using the
              mke2fs program using the -n option to print out where the
              superblocks exist, supposing mke2fs is supplied with arguments
              that are consistent with the filesystem's layout (e.g.
              blocksize, blocks per group, sparse_super, etc.).

              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

       -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

       -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 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

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

                          During pass 1, print a detailed report of any
                          discontiguous 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
                          eliminating unnecessary width or depth.  This can
                          also be enabled in the options section of

                          Offer to optimize the extent tree by eliminating
                          unnecessary width or depth.  This is the default
                          unless otherwise specified in /etc/e2fsck.conf.

                          Trade off using memory for speed when checking a
                          file system with a large number of hard-linked
                          files.  The amount of memory required is
                          proportional to the number of inodes in the file
                          system.  For large file systems, this can be
                          gigabytes of memory.  (For example, a 40TB file
                          system with 2.8 billion inodes will consume an
                          additional 5.7 GB memory if this optimization is
                          enabled.)  This optimization can also be enabled
                          in the options section of /etc/e2fsck.conf.

                          Disable the inode_count_fullmap optimization.
                          This is the default unless otherwise specified in

                          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 filesystem); if this amount is more than
                          1/50th of total physical memory, readahead is
                          disabled.  Set this to zero to disable readahead

                          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

                          If the filesystem has shared blocks, with the
                          shared blocks read-only feature enabled, then this
                          will unshare all shared blocks and unset the read-
                          only feature bit. If there is not enough free
                          space then the operation will fail.  If the
                          filesystem does not have the read-only feature
                          bit, but has shared blocks anyway, then this
                          option will have no effect. Note when using this
                          option, if there is no free space to clone blocks,
                          there is no prompt to delete files and instead the
                          operation will fail.

                          Note that unshare_blocks implies the "-f" option
                          to ensure that all passes are run. Additionally,
                          if "-n" is also specified, e2fsck will simulate
                          trying to allocate enough space to deduplicate. If
                          this fails, the exit code will be non-zero.

       -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.

       -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.

EXIT CODE         top

       The exit code returned by e2fsck is the sum of the following
            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         top

       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.

REPORTING BUGS         top

       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.

ENVIRONMENT         top

              Determines the location of the configuration file (see

AUTHOR         top

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

SEE ALSO         top

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

COLOPHON         top

       This page is part of the e2fsprogs (utilities for ext2/3/4
       filesystems) project.  Information about the project can be found at
       ⟨http://e2fsprogs.sourceforge.net/⟩.  It is not known how to report
       bugs for this man page; if you know, please send a mail to
       man-pages@man7.org.  This page was obtained from the project's up‐
       stream Git repository
       ⟨git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git⟩ on 2020-11-01.
       (At that time, the date of the most recent commit that was found in
       the repository was 2020-10-01.)  If you discover any rendering prob‐
       lems in this HTML version of the page, or you believe there is a bet‐
       ter or more up-to-date source for the page, or you have corrections
       or improvements to the information in this COLOPHON (which is not
       part of the original manual page), send a mail to man-pages@man7.org

E2fsprogs version 1.46-WIP       March 2020                        E2FSCK(8)

Pages that refer to this page: fuse2fs(1)lseek64(3)e2fsck.conf(5)ext2(5)ext3(5)ext4(5)mke2fs.conf(5)badblocks(8)debugfs(8)dumpe2fs(8)e2freefrag(8)e2mmpstatus(8)fsck(8@@e2fsprogs)fsck(8)mke2fs(8)mklost+found(8)quotacheck(8)resize2fs(8)tune2fs(8)