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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT CODE | SIGNALS | REPORTING BUGS | AUTHOR | SEE ALSO | COLOPHON |
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 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.
-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.
no_optimize_extents
Do not offer to optimize the extent tree by
eliminating unnecessary width or depth.
readahead_kb
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
entirely.
bmap2extent
Convert block-mapped files to extent-mapped files.
fixes_only
Only fix damaged metadata; do not optimize htree
directories or compress extent trees. This option
is incompatible with the -D and -E bmap2extent
options.
-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.
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.
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.
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.
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)
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
upstream Git repository
⟨git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git⟩ on 2017-07-05.
If you discover any rendering problems in this HTML version of the
page, or you believe there is a better 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 1.43.5-WIP February 2017 E2FSCK(8)
Pages that refer to this page: fuse2fs(1), lseek64(3), e2fsck.conf(5), ext4(5), mke2fs.conf(5), badblocks(8), debugfs(8), dumpe2fs(8), e2freefrag(8), fsck(8@@e2fsprogs), fsck(8), mke2fs(8), mklost+found(8), mount(8), quotacheck(8), resize2fs(8), tune2fs(8)