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 file systems 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 file systems that use journaling, e2fsck will normally  re‐
       play 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 file systems.  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 file system is mounted.   If e2fsck asks whether or not you should check a file system 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 file system.  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.

       -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 backup superblocks is  dependent  on  the
              file system'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 file system's  layout
              (e.g. blocksize, blocks per group, sparse_super, etc.).

              If an alternative superblock is specified and the file system is not opened read-only, e2fsck will make sure that the
              primary superblock is updated appropriately upon completion of the file system 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 su‐
              perblock 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 file system 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 file system.  This option causes e2fsck to try to optimize all directories, either by  re-in‐
              dexing  them  if  the file system supports directory indexing,  or by sorting and compressing directories for smaller
              directories, or for file systems 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 file system 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 file sys‐
                          tem.  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 perform any further checks or repairs.

                          During pass 1, print a detailed report of any discontiguous blocks for files in the file system.

                          Attempt to discard free blocks and unused inode blocks after  the  full  file  system  check  (discarding
                          blocks is useful on solid state devices and sparse / thin-provisioned storage). Note that discard is done
                          in pass 5 AFTER the file system has been fully checked and only if it does not contain  recognizable  er‐
                          rors. 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 en‐
                          abled in the options section of /etc/e2fsck.conf.

                          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  en‐
                          abled 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 file system);
                          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 options.

                          Force verification of encoded filenames in case-insensitive directories.  This is the default mode if the
                          file system has the strict flag enabled.

                          If  the  file  system 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 file system 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 file system 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 file system 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 file system.  Hence, badblocks(8) must be given the blocksize of the file system in order to obtain  correct  re‐
              sults.   As a result, it is much simpler and safer to use the -c option to e2fsck, since it will assure that the cor‐
              rect 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 file system 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  file  system
              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 spec‐
              ified 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 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

       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 option.)

              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 file system 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
       file system 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 af‐
       ter 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 file system, 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.

              Determines the location of the configuration file (see e2fsck.conf(5)).

       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 1.47.0                                   February 2023                                                  E2FSCK(8)