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e2fsck - check a Linux ext2/ext3 file system
e2fsck [ -pacnyrdfkvstDFSV ] [ -b superblock ] [ -B blocksize ] [ -l|-L
bad_blocks_file ] [ -C fd ] [ -j external-journal ] [ -E
extended_options ] device
e2fsck is used to check a Linux second extended file system (ext2fs).
E2fsck also supports ext2 filesystems containing a journal, which are
also sometimes known as ext3 filesystems, by first applying the journal
to the filesystem before continuing with normal e2fsck processing.
After the journal has been applied, a filesystem will normally be
marked as clean. Hence, for ext3 filesystems, e2fsck will normally run
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.
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.
- 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
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
- -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.
- This option causes e2fsck to run the badblocks(8)
find any blocks which are bad on the filesystem, and then marks
them as bad by adding them to the bad block inode. 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 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.
- Print debugging output (useless unless you are debugging
- 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.
- -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:
Assume the format of the extended attribute blocks
in the filesystem is the specified version number.
The version number may be 1 or 2. The default
extended attribute version format is 2.
- Force checking even if the file system seems clean.
- 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.
- When combined with the -c option, any existing bad blocks in the
bad blocks list are preserved, and any new bad blocks found by
will be added to the existing bad blocks
- -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.
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
- -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.)
- Open the filesystem read-only, and assume an answer of ‘no’ to
all questions. Allows e2fsck to be used non-interactively.
(Note: if the -c, -l, or -L options are specified in addition to
the -n option, then the filesystem will be opened read-write, to
permit the bad-blocks list to be updated. However, no other
changes will be made to the filesystem.)
- Automatically repair ("preen") the file system without any questions.
- This option does nothing at all; it is provided only for backwards
- This option will byte-swap the filesystem so that it is using
the normalized, standard byte-order (which is i386 or little
endian). If the filesystem is already in the standard byteorder,
e2fsck will take no action.
- This option will byte-swap the filesystem, regardless of its
- Print timing statistics for e2fsck. If this option is used
twice, additional timing statistics are printed on a pass by
- Verbose mode.
- Print version information and exit.
- Assume an answer of ‘yes’ to all questions; allows e2fsck to be
The exit code returned by e2fsck is the sum of the following conditions:
- - No errors
- - File system errors corrected
- - File system errors corrected, system should
- - File system errors left uncorrected
- - Operational error
- - Usage or syntax error
- - 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.
(See discussion of the -C option.)
This signal causes e2fsck to stop displaying a completion bar.
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
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)
most useful data you can send to help reproduce the bug is a compressed
raw image dump of the filesyste, generated using e2image(8)
. See the
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 <email@example.com>.
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