-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 backup superblocks is
dependent on the file system's blocksize, the number of
blocks per group, and features such as sparse_super.
Additional backup superblocks can be determined by using
the mke2fs program using the -n option to print out where
the superblocks exist, supposing mke2fs is supplied with
arguments that are consistent with the file system's
layout (e.g. blocksize, blocks per group, sparse_super,
etc.).
If an alternative superblock is specified and the file
system is not opened read-only, e2fsck will make sure that
the primary superblock is updated appropriately upon
completion of the file system 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 file system 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 file system. This option causes
e2fsck to try to optimize all directories, either by re-
indexing them if the file system supports directory
indexing, or by sorting and compressing directories for
smaller directories, or for file systems 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 file system 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 file system. 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 file
system.
discard
Attempt to discard free blocks and unused
inode blocks after the full file system check
(discarding blocks is useful on solid state
devices and sparse / thin-provisioned
storage). Note that discard is done in pass 5
AFTER the file system 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. This
can also be enabled in the options section of
/etc/e2fsck.conf.
optimize_extents
Offer to optimize the extent tree by
eliminating unnecessary width or depth. This
is the default unless otherwise specified in
/etc/e2fsck.conf.
inode_count_fullmap
Trade off using memory for speed when checking
a file system with a large number of hard-
linked files. The amount of memory required
is proportional to the number of inodes in the
file system. For large file systems, this can
be gigabytes of memory. (For example, a 40TB
file system with 2.8 billion inodes will
consume an additional 5.7 GB memory if this
optimization is enabled.) This optimization
can also be enabled in the options section of
/etc/e2fsck.conf.
no_inode_count_fullmap
Disable the inode_count_fullmap optimization.
This is the default unless otherwise specified
in /etc/e2fsck.conf.
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 file system); 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.
check_encoding
Force verification of encoded filenames in
case-insensitive directories. This is the
default mode if the file system has the strict
flag enabled.
unshare_blocks
If the file system has shared blocks, with the
shared blocks read-only feature enabled, then
this will unshare all shared blocks and unset
the read-only feature bit. If there is not
enough free space then the operation will
fail. If the file system does not have the
read-only feature bit, but has shared blocks
anyway, then this option will have no effect.
Note when using this option, if there is no
free space to clone blocks, there is no prompt
to delete files and instead the operation will
fail.
Note that unshare_blocks implies the "-f"
option to ensure that all passes are run.
Additionally, if "-n" is also specified,
e2fsck will simulate trying to allocate enough
space to deduplicate. If this fails, the exit
code will be non-zero.
-f Force checking even if the file system seems clean.
-F Flush the file system 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 file
system 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 file system. Hence, badblocks(8) must be
given the blocksize of the file system 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 file system 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 file
system 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.
