E2FSCK
Section: Maintenance Commands (8)
Updated: May 2010
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.
- fragcheck
-
During pass 1, print a detailed report of any discontiguous blocks for
files in the filesystem.
- -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)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- OPTIONS
-
- EXIT CODE
-
- SIGNALS
-
- REPORTING BUGS
-
- AUTHOR
-
- SEE ALSO
-
This document was created by
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Time: 07:35:44 GMT, March 26, 2013