.\"
.TH E2FSCK 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
.SH NAME
-e2fsck \- check a Linux second extended file system
+e2fsck \- check a Linux ext2/ext3/ext4 file system
.SH SYNOPSIS
.B e2fsck
[
-.B \-pacnyrdfvstFSV
+.B \-pacnyrdfkvtDFV
]
[
.B \-b
.I blocksize
]
[
-.B \-l|-L
+.BR \-l | \-L
.I bad_blocks_file
]
+[
+.B \-C
+.I fd
+]
+@JDEV@[
+@JDEV@.B \-j
+@JDEV@.I external-journal
+@JDEV@]
+[
+.B \-E
+.I extended_options
+]
.I device
.SH DESCRIPTION
.B e2fsck
-is used to check a Linux second extended file system.
-.TP
+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,
+.B e2fsck
+will normally replay the journal and exit, unless its superblock
+indicates that further checking is required.
+.PP
.I device
-is the special file corresponding to the device (e.g /dev/hdXX).
+is the device file where the filesystem is stored (e.g.
+.IR /dev/hdc1 ).
+.PP
+Note that in general it is not safe to run
+.B e2fsck
+on mounted filesystems. The only exception is if the
+.B \-n
+option is specified, and
+.BR \-c ,
+.BR \-l ,
+or
+.B -L
+options are
+.I not
+specified. However, even if it is safe to do so, the results printed by
+.B e2fsck
+are not valid if the filesystem is mounted. If
+.B 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.
.SH OPTIONS
.TP
-.I -a
+.B \-a
This option does the same thing as the
-.I -p
+.B \-p
option. It is provided for backwards compatibility only; it is
suggested that people use
-.I -p
+.B \-p
option whenever possible.
.TP
-.I -b superblock
+.BI \-b " superblock"
Instead of using the normal superblock, use an alternative superblock
specified by
-.IR superblock . This option is normally used when the primary superblock
-has been corrupted; most filesystems have primary superblocks located at
-blocks 8193, 16385, etc. If an alternative superblock is specified and
+.IR 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.
+.IP
+Additional backup superblocks can be determined by using the
+.B mke2fs
+program using the
+.B \-n
+option to print out where the superblocks were created. The
+.B \-b
+option to
+.BR mke2fs ,
+which specifies blocksize of the filesystem must be specified in order
+for the superblock locations that are printed out to be accurate.
+.IP
+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.
.TP
-.I -B blocksize
+.BI \-B " blocksize"
Normally,
.B e2fsck
will search for the superblock at various different
.B e2fsck
will terminate with a fatal error.
.TP
-.I -c
+.B \-c
This option causes
.B e2fsck
-to run the
+to use
.BR badblocks (8)
-program to find any blocks which are bad on the filesystem,
-and then marks them as bad by adding them to the bad block inode.
+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.
.TP
-.I -d
+.BI \-C " fd"
+This option causes
+.B 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
+.BR 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
+.B e2fsck
+process a SIGUSR1 signal.
+If the file descriptor specified is 0,
+.B e2fsck
+will print a completion bar as it goes about its business. This requires
+that e2fsck is running on a video console or terminal.
+.TP
+.B \-d
Print debugging output (useless unless you are debugging
.BR e2fsck ).
.TP
-.I -f
+.B \-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.
+.IP
+Even without the
+.B \-D
+option,
+.B 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
+.B \-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.
+.IP
+The
+.B \-D
+option will detect directory entries with duplicate names in a single
+directory, which e2fsck normally does not enforce for performance reasons.
+.TP
+.BI \-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:
+.RS 1.2i
+.TP
+.BI ea_ver= extended_attribute_version
+Set the version of the extended attribute blocks which
+.B e2fsck
+will require while checking the filesystem. The version number may
+be 1 or 2. The default extended attribute version format is 2.
+.TP
+.BI journal_only
+Only replay the journal if required, but do not perform any further checks
+or repairs.
+.TP
+.BI fragcheck
+During pass 1, print a detailed report of any discontiguous blocks for
+files in the filesystem.
+.TP
+.BI 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
+.B e2fsck
+does not fully recognize a problem and hence in this case this
+option may prevent you from further manual data recovery.
+.TP
+.BI 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.
+.RE
+.TP
+.B \-f
Force checking even if the file system seems clean.
.TP
-.I -F
+.B \-F
Flush the filesystem device's buffer caches before beginning. Only
really useful for doing
.B e2fsck
time trials.
+@JDEV@.TP
+@JDEV@.BI \-j " external-journal"
+@JDEV@Set the pathname where the external-journal for this filesystem can be
+@JDEV@found.
.TP
-.I -l filename
-Add the blocks listed in the file specified by
+.BI \-k
+When combined with the
+.B \-c
+option, any existing bad blocks in the bad blocks list are preserved,
+and any new bad blocks found by running
+.BR badblocks (8)
+will be added to the existing bad blocks list.
+.TP
+.BI \-l " filename"
+Add the block numbers listed in the file specified by
.I filename
-to the list of bad blocks.
+to the list of bad blocks. The format of this file is the same as the
+one generated by the
+.BR badblocks (8)
+program. Note that the block numbers are based on the blocksize
+of the filesystem. Hence,
+.BR 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
+.B -c
+option to
+.BR e2fsck ,
+since it will assure that the correct parameters are passed to the
+.B badblocks
+program.
.TP
-.I -L filename
+.BI \-L " filename"
Set the bad blocks list to be the list of blocks specified by
.IR filename .
(This option is the same as the
-.I -l
+.B \-l
option, except the bad blocks list is cleared before the blocks listed
in the file are added to the bad blocks list.)
.TP
-.I -n
-Open the filesystem read-only, and assume an answer of ``no'' to all
+.B \-n
+Open the filesystem read-only, and assume an answer of `no' to all
questions. Allows
.B e2fsck
-to be used non-interactively. (Note: if the
-.IR -c ,
-.IR -l ,
+to be used non-interactively. This option
+may not be specified at the same time as the
+.B \-p
or
-.I -L
-options are specified in addition to the
-.I -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.)
+.B \-y
+options.
.TP
-.I -p
-Automatically repair ("preen") the file system without any questions.
+.B \-p
+Automatically repair ("preen") the file system. This option will cause
+.B e2fsck
+to automatically
+fix any filesystem problems that can be safely fixed without human
+intervention. If
+.B e2fsck
+discovers a problem which may require the system administrator
+to take additional corrective action,
+.B e2fsck
+will print a description of the problem and then exit with the value 4
+logically or'ed into the exit code. (See the \fBEXIT CODE\fR section.)
+This option is normally used by the system's boot scripts. It may not
+be specified at the same time as the
+.B \-n
+or
+.B \-y
+options.
.TP
-.I -r
+.B \-r
This option does nothing at all; it is provided only for backwards
compatibility.
-.TP
-.I -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,
-.B e2fsck
-will take no action.
-.TP
-.I -S
-This option will byte-swap the filesystem, regardless of its current
-byte-order.
.TP
-.I -t
+.B \-t
Print timing statistics for
.BR e2fsck .
If this option is used twice, additional timing statistics are printed
on a pass by pass basis.
.TP
-.I -v
+.B \-v
Verbose mode.
.TP
-.I -V
+.B \-V
Print version information and exit.
.TP
-.I -y
-Assume an answer of ``yes'' to all questions; allows
+.B \-y
+Assume an answer of `yes' to all questions; allows
.B e2fsck
-to be used non-interactively.
+to be used non-interactively. This option
+may not be specified at the same time as the
+.B \-n
+or
+.B \-p
+options.
.SH EXIT CODE
The exit code returned by
.B e2fsck
.br
\ 2\ \-\ File system errors corrected, system should
.br
-\ \ \ \ be rebooted if file system was mounted
+\ \ \ \ be rebooted
.br
\ 4\ \-\ File system errors left uncorrected
.br
.br
\ 16\ \-\ Usage or syntax error
.br
+\ 32\ \-\ E2fsck canceled by user request
+.br
\ 128\ \-\ Shared library error
.br
+.SH SIGNALS
+The following signals have the following effect when sent to
+.BR e2fsck .
+.TP
+.B SIGUSR1
+This signal causes
+.B e2fsck
+to start displaying a completion bar or emitting progress information.
+(See discussion of the
+.B \-C
+option.)
+.TP
+.B SIGUSR2
+This signal causes
+.B e2fsck
+to stop displaying a completion bar or emitting progress information.
.SH REPORTING BUGS
Almost any piece of software will have bugs. If you manage to find a
filesystem which causes
Please include as much information as possible in your bug report.
Ideally, include a complete transcript of the
.B e2fsck
-run, so I can see exactly what error messages are displayed. If you
-have a writeable filesystem where the transcript can be stored, the
+run, so I can see exactly what error messages are displayed. (Make sure
+the messages printed by
+.B e2fsck
+are in English; if your system has been
+configured so that
+.BR e2fsck 's
+messages have been translated into another language, please set the the
+.B LC_ALL
+environment variable to
+.B 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
.BR script (1)
program is a handy way to save the output of
.B e2fsck
.I dump
command will allow you to extract the contents of the directory inode,
which can sent to me after being first run through
-.BR uuencode (1).
+.BR 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
+.BR e2image (8).
+See the
+.BR e2image (8)
+man page for more details.
.PP
Always include the full version string which
.B e2fsck
.B e2fsck
was written by Theodore Ts'o <tytso@mit.edu>.
.SH SEE ALSO
-.BR mke2fs (8),
-.BR tune2fs (8),
+.BR e2fsck.conf (5),
+.BR badblocks (8),
.BR dumpe2fs (8),
-.BR debugfs (8)
+.BR debugfs (8),
+.BR e2image (8),
+.BR mke2fs (8),
+.BR tune2fs (8)
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