From Linux Man Pages
e2fsck - check a Linux ext2/ext3 file system
SYNOPSIS
e2fsck [ -pacnyrdfkvstDFSV ] [ -b superblock ] [ -B blocksize ] [ -l|-L bad_blocks_file ] [ -C fd ] [ -j exter-
nal-journal ] [ -E extended_options ] device
DESCRIPTION
e2fsck is used to check a Linux second extended file system (ext2fs). E2fsck also supports ext2 filesystems con-
taining 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. /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 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 directo-
ries 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:
ea_ver=extended_attribute_version
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.
-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 filesys-
tem 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. (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.) 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 case 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.
-s 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 byte-order, e2fsck will take no
action.
-S This option will byte-swap the filesystem, regardless of its current byte-order.
-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. (See discussion of the -C option.)
SIGUSR2
This signal causes e2fsck to stop displaying a completion bar.
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 run-
ning.
RELATED
badblocks(8), dumpe2fs(8), debugfs(8), e2image(8), mke2fs(8), tune2fs(8)
CATEGORY