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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 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 spec-
ified. 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 back-
wards compatibility only; it is suggested that people use -p option whenever
possible.
-b superblock
Instead of using the normal superblock, use an alternative superblock speci-
fied 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 block-
sizes, 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 sup-
pressed 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 sup-
ports directory indexing, or by sorting and compressing directories for
smaller directories, or for filesystems using traditional linear directo-
ries.
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.
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 recog-
nise 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 block-
size 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 ques-
tions. 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 nor-
mally 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 compati-
bility.
-t Print timing statistics for e2fsck. If this option is used twice, addi-
tional 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 AT mit.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)
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On Apache/2.2.15 (CentOS)
Under GNU General Public License
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