Provided by: e2fsck-static_1.42.13-1ubuntu1_amd64 bug

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 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 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:

                   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.

                   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 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 <tytso@mit.edu>.

SEE ALSO

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