2 .\" Copyright 1993, 1994, 1995 by Theodore Ts'o. All Rights Reserved.
3 .\" This file may be copied under the terms of the GNU Public License.
5 .TH E2FSCK 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
7 e2fsck \- check a Linux ext2/ext3/ext4 file system
31 @JDEV@.I external-journal
44 is used to check the ext2/ext3/ext4 family of file systems.
45 For ext3 and ext4 file systems that use a journal, if the system has been
46 shut down uncleanly without any errors, normally, after replaying the
47 committed transactions in the journal, the file system should be
48 marked as clean. Hence, for file systems that use journaling,
50 will normally replay the journal and exit, unless its superblock
51 indicates that further checking is required.
54 is a block device (e.g.,
56 or file containing the file system.
58 Note that in general it is not safe to run
60 on mounted file systems. The only exception is if the
62 option is specified, and
69 specified. However, even if it is safe to do so, the results printed by
71 are not valid if the file system is mounted. If
73 asks whether or not you should check a file system which is mounted,
74 the only correct answer is ``no''. Only experts who really know what
75 they are doing should consider answering this question in any other way.
79 is run in interactive mode (meaning that none of
84 are specified), the program will ask the user to fix each problem found in the
85 file system. A response of 'y' will fix the error; 'n' will leave the error
86 unfixed; and 'a' will fix the problem and all subsequent problems; pressing
87 Enter will proceed with the default response, which is printed before the
88 question mark. Pressing Control-C terminates e2fsck immediately.
92 This option does the same thing as the
94 option. It is provided for backwards compatibility only; it is
95 suggested that people use
97 option whenever possible.
100 Instead of using the normal superblock, use an alternative superblock
103 This option is normally used when the primary superblock has been
104 corrupted. The location of backup superblocks is dependent on the
105 file system's blocksize, the number of blocks per group, and features
109 Additional backup superblocks can be determined by using the
113 option to print out where the superblocks exist, supposing
115 is supplied with arguments that are consistent with the file system's layout
116 (e.g. blocksize, blocks per group,
120 If an alternative superblock is specified and
121 the file system is not opened read-only, e2fsck will make sure that the
122 primary superblock is updated appropriately upon completion of the
128 will search for the superblock at various different
129 block sizes in an attempt to find the appropriate block size.
130 This search can be fooled in some cases. This option forces
132 to only try locating the superblock at a particular blocksize.
133 If the superblock is not found,
135 will terminate with a fatal error.
142 program to do a read-only scan of the device in order to find any bad
143 blocks. If any bad blocks are found, they are added to the bad block
144 inode to prevent them from being allocated to a file or directory. If
145 this option is specified twice, then the bad block scan will be done
146 using a non-destructive read-write test.
151 to write completion information to the specified file descriptor
152 so that the progress of the file system
153 check can be monitored. This option is typically used by programs
156 If the file descriptor number is negative, then absolute value of
157 the file descriptor will be used, and the progress information will be
158 suppressed initially. It can later be enabled by sending the
160 process a SIGUSR1 signal.
161 If the file descriptor specified is 0,
163 will print a completion bar as it goes about its business. This requires
164 that e2fsck is running on a video console or terminal.
167 Print debugging output (useless unless you are debugging
171 Optimize directories in file system. This option causes e2fsck to
172 try to optimize all directories, either by re-indexing them if the
173 file system supports directory indexing, or by sorting and compressing
174 directories for smaller directories, or for file systems using
175 traditional linear directories.
181 may sometimes optimize a few directories --- for example, if
182 directory indexing is enabled and a directory is not indexed and would
183 benefit from being indexed, or if the index structures are corrupted
184 and need to be rebuilt. The
186 option forces all directories in the file system to be optimized. This can
187 sometimes make them a little smaller and slightly faster to search, but
188 in practice, you should rarely need to use this option.
192 option will detect directory entries with duplicate names in a single
193 directory, which e2fsck normally does not enforce for performance reasons.
195 .BI \-E " extended_options"
196 Set e2fsck extended options. Extended options are comma
197 separated, and may take an argument using the equals ('=') sign. The
198 following options are supported:
202 Resolve files with shared blocks in pass 1D by giving each file a private
203 copy of the blocks (dup);
204 or replacing the shared blocks with private, zero-filled blocks (zero).
207 .BI shared= preserve|lost+found|delete
208 Files with shared blocks discovered in pass 1D are cloned and then left
210 cloned and then disconnected from their parent directory,
211 then reconnected to /lost+found in pass 3 (lost+found);
212 or simply deleted (delete). The default is preserve.
214 .BI ea_ver= extended_attribute_version
215 Set the version of the extended attribute blocks which
217 will require while checking the file system. The version number may
218 be 1 or 2. The default extended attribute version format is 2.
221 Only replay the journal if required, but do not perform any further checks
225 During pass 1, print a detailed report of any discontiguous blocks for
226 files in the file system.
229 Attempt to discard free blocks and unused inode blocks after the full
230 file system check (discarding blocks is useful on solid state devices and sparse
231 / thin-provisioned storage). Note that discard is done in pass 5 AFTER the
232 file system has been fully checked and only if it does not contain recognizable
233 errors. However there might be cases where
235 does not fully recognize a problem and hence in this case this
236 option may prevent you from further manual data recovery.
239 Do not attempt to discard free blocks and unused inode blocks. This option is
240 exactly the opposite of discard option. This is set as default.
242 .BI no_optimize_extents
243 Do not offer to optimize the extent tree by eliminating unnecessary
244 width or depth. This can also be enabled in the options section of
245 .BR /etc/e2fsck.conf .
248 Offer to optimize the extent tree by eliminating unnecessary
249 width or depth. This is the default unless otherwise specified in
250 .BR /etc/e2fsck.conf .
252 .BI inode_count_fullmap
253 Trade off using memory for speed when checking a file system with a
254 large number of hard-linked files. The amount of memory required is
255 proportional to the number of inodes in the file system. For large file
256 systems, this can be gigabytes of memory. (For example, a 40TB file system
257 with 2.8 billion inodes will consume an additional 5.7 GB memory if this
258 optimization is enabled.) This optimization can also be enabled in the
260 .BR /etc/e2fsck.conf .
262 .BI no_inode_count_fullmap
264 .B inode_count_fullmap
265 optimization. This is the default unless otherwise specified in
266 .BR /etc/e2fsck.conf .
269 Use this many KiB of memory to pre-fetch metadata in the hopes of reducing
270 e2fsck runtime. By default, this is set to the size of two block groups' inode
271 tables (typically 4MiB on a regular ext4 file system); if this amount is more
272 than 1/50th of total physical memory, readahead is disabled. Set this to zero
273 to disable readahead entirely.
276 Convert block-mapped files to extent-mapped files.
279 Only fix damaged metadata; do not optimize htree directories or compress
280 extent trees. This option is incompatible with the -D and -E bmap2extent
284 Force verification of encoded filenames in case-insensitive directories.
285 This is the default mode if the file system has the strict flag enabled.
288 If the file system has shared blocks, with the shared blocks read-only feature
289 enabled, then this will unshare all shared blocks and unset the read-only
290 feature bit. If there is not enough free space then the operation will fail.
291 If the file system does not have the read-only feature bit, but has shared
292 blocks anyway, then this option will have no effect. Note when using this
293 option, if there is no free space to clone blocks, there is no prompt to
294 delete files and instead the operation will fail.
296 Note that unshare_blocks implies the "-f" option to ensure that all passes
297 are run. Additionally, if "-n" is also specified, e2fsck will simulate trying
298 to allocate enough space to deduplicate. If this fails, the exit code will
303 Force checking even if the file system seems clean.
306 Flush the file system device's buffer caches before beginning. Only
307 really useful for doing
311 @JDEV@.BI \-j " external-journal"
312 @JDEV@Set the pathname where the external-journal for this file system can be
316 When combined with the
318 option, any existing bad blocks in the bad blocks list are preserved,
319 and any new bad blocks found by running
321 will be added to the existing bad blocks list.
324 Add the block numbers listed in the file specified by
326 to the list of bad blocks. The format of this file is the same as the
329 program. Note that the block numbers are based on the blocksize
330 of the file system. Hence,
332 must be given the blocksize of the file system in order to obtain correct
333 results. As a result, it is much simpler and safer to use the
337 since it will assure that the correct parameters are passed to the
342 Set the bad blocks list to be the list of blocks specified by
344 (This option is the same as the
346 option, except the bad blocks list is cleared before the blocks listed
347 in the file are added to the bad blocks list.)
350 Run e2fsck with up to the specified number of
352 The actual number of threads may be lower, if the filesystem does not
353 have enough block groups to effectively parallelize the workload.
356 Open the file system read-only, and assume an answer of `no' to all
359 to be used non-interactively. This option
360 may not be specified at the same time as the
367 Automatically repair ("preen") the file system. This option will cause
370 fix any file system problems that can be safely fixed without human
373 discovers a problem which may require the system administrator
374 to take additional corrective action,
376 will print a description of the problem and then exit with the value 4
377 logically or'ed into the exit code. (See the \fBEXIT CODE\fR section.)
378 This option is normally used by the system's boot scripts. It may not
379 be specified at the same time as the
386 This option does nothing at all; it is provided only for backwards
390 Print timing statistics for
392 If this option is used twice, additional timing statistics are printed
393 on a pass by pass basis.
399 Print version information and exit.
402 Assume an answer of `yes' to all questions; allows
404 to be used non-interactively. This option
405 may not be specified at the same time as the
412 Before overwriting a file system block, write the old contents of the block to
413 an undo file. This undo file can be used with e2undo(8) to restore the old
414 contents of the file system should something go wrong. If the empty string is
415 passed as the undo_file argument, the undo file will be written to a file named
416 e2fsck-\fIdevice\fR.e2undo in the directory specified via the
417 \fIE2FSPROGS_UNDO_DIR\fR environment variable.
419 WARNING: The undo file cannot be used to recover from a power or system crash.
421 The exit code returned by
423 is the sum of the following conditions:
427 \ 1\ \-\ File system errors corrected
429 \ 2\ \-\ File system errors corrected, system should
433 \ 4\ \-\ File system errors left uncorrected
435 \ 8\ \-\ Operational error
437 \ 16\ \-\ Usage or syntax error
439 \ 32\ \-\ E2fsck canceled by user request
441 \ 128\ \-\ Shared library error
444 The following signals have the following effect when sent to
450 to start displaying a completion bar or emitting progress information.
451 (See discussion of the
458 to stop displaying a completion bar or emitting progress information.
460 Almost any piece of software will have bugs. If you manage to find a
461 file system which causes
465 is unable to repair, please report it to the author.
467 Please include as much information as possible in your bug report.
468 Ideally, include a complete transcript of the
470 run, so I can see exactly what error messages are displayed. (Make sure
471 the messages printed by
473 are in English; if your system has been
476 messages have been translated into another language, please set the the
478 environment variable to
480 so that the transcript of e2fsck's output will be useful to me.)
482 have a writable file system where the transcript can be stored, the
484 program is a handy way to save the output of
488 It is also useful to send the output of
490 If a specific inode or inodes seems to be giving
492 trouble, try running the
494 command and send the output of the
496 command run on the relevant inode(s). If the inode is a directory, the
499 command will allow you to extract the contents of the directory inode,
500 which can sent to me after being first run through
502 The most useful data you can send to help reproduce
503 the bug is a compressed raw image dump of the file system, generated using
507 man page for more details.
509 Always include the full version string which
511 displays when it is run, so I know which version you are running.
515 Determines the location of the configuration file (see
516 .BR e2fsck.conf (5)).
520 was written by Theodore Ts'o <tytso@mit.edu>.