1E2FSCK(8) System Manager's Manual E2FSCK(8)
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6 e2fsck - check a Linux ext2/ext3/ext4 file system
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9 e2fsck [ -pacnyrdfkvtDFV ] [ -b superblock ] [ -B blocksize ] [ -l|-L
10 bad_blocks_file ] [ -C fd ] [ -j external-journal ] [ -E
11 extended_options ] [ -z undo_file ] device
12
14 e2fsck is used to check the ext2/ext3/ext4 family of file systems. For
15 ext3 and ext4 filesystems that use a journal, if the system has been
16 shut down uncleanly without any errors, normally, after replaying the
17 committed transactions in the journal, the file system should be
18 marked as clean. Hence, for filesystems that use journalling, e2fsck
19 will normally replay the journal and exit, unless its superblock indi‐
20 cates that further checking is required.
21 device is a block device (e.g., /dev/sdc1) or file containing the file
23 system.
24 Note that in general it is not safe to run e2fsck on mounted filesys‐
26 tems. The only exception is if the -n option is specified, and -c, -l,
27 or -L options are not specified. However, even if it is safe to do
28 so, the results printed by e2fsck are not valid if the filesystem is
29 mounted. If e2fsck asks whether or not you should check a filesystem
30 which is mounted, the only correct answer is ``no''. Only experts who
31 really know what they are doing should consider answering this question
32 in any other way.
33 If e2fsck is run in interactive mode (meaning that none of -y, -n, or
35 -p are specified), the program will ask the user to fix each problem
36 found in the filesystem. A response of 'y' will fix the error; 'n'
37 will leave the error unfixed; and 'a' will fix the problem and all sub‐
38 sequent problems; pressing Enter will proceed with the default
39 response, which is printed before the question mark. Pressing Control-
40 C terminates e2fsck immediately.
41
43 -a This option does the same thing as the -p option. It is pro‐
44 vided for backwards compatibility only; it is suggested that
45 people use -p option whenever possible.
46 -b superblock
48 Instead of using the normal superblock, use an alternative
49 superblock specified by superblock. This option is normally
50 used when the primary superblock has been corrupted. The loca‐
51 tion of backup superblocks is dependent on the filesystem's
52 blocksize, the number of blocks per group, and features such as
53 sparse_super.
54 Additional backup superblocks can be determined by using the
56 mke2fs program using the -n option to print out where the
57 superblocks exist, supposing mke2fs is supplied with arguments
58 that are consistent with the filesystem's layout (e.g. block‐
59 size, blocks per group, sparse_super, etc.).
60 If an alternative superblock is specified and the filesystem is
62 not opened read-only, e2fsck will make sure that the primary
63 superblock is updated appropriately upon completion of the
64 filesystem check.
65 -B blocksize
67 Normally, e2fsck will search for the superblock at various dif‐
68 ferent block sizes in an attempt to find the appropriate block
69 size. This search can be fooled in some cases. This option
70 forces e2fsck to only try locating the superblock at a particu‐
71 lar blocksize. If the superblock is not found, e2fsck will ter‐
72 minate with a fatal error.
73 -c This option causes e2fsck to use badblocks(8) program to do a
75 read-only scan of the device in order to find any bad blocks.
76 If any bad blocks are found, they are added to the bad block
77 inode to prevent them from being allocated to a file or direc‐
78 tory. If this option is specified twice, then the bad block
79 scan will be done using a non-destructive read-write test.
80 -C fd This option causes e2fsck to write completion information to the
82 specified file descriptor so that the progress of the filesystem
83 check can be monitored. This option is typically used by pro‐
84 grams which are running e2fsck. If the file descriptor number
85 is negative, then absolute value of the file descriptor will be
86 used, and the progress information will be suppressed initially.
87 It can later be enabled by sending the e2fsck process a SIGUSR1
88 signal. If the file descriptor specified is 0, e2fsck will
89 print a completion bar as it goes about its business. This
90 requires that e2fsck is running on a video console or terminal.
91 -d Print debugging output (useless unless you are debugging
93 e2fsck).
94 -D Optimize directories in filesystem. This option causes e2fsck
96 to try to optimize all directories, either by reindexing them if
97 the filesystem supports directory indexing, or by sorting and
98 compressing directories for smaller directories, or for filesys‐
99 tems using traditional linear directories.
100 Even without the -D option, e2fsck may sometimes optimize a few
102 directories --- for example, if directory indexing is enabled
103 and a directory is not indexed and would benefit from being
104 indexed, or if the index structures are corrupted and need to be
105 rebuilt. The -D option forces all directories in the filesystem
106 to be optimized. This can sometimes make them a little smaller
107 and slightly faster to search, but in practice, you should
108 rarely need to use this option.
109 The -D option will detect directory entries with duplicate names
111 in a single directory, which e2fsck normally does not enforce
112 for performance reasons.
113 -E extended_options
115 Set e2fsck extended options. Extended options are comma sepa‐
116 rated, and may take an argument using the equals ('=') sign.
117 The following options are supported:
118 ea_ver=extended_attribute_version
120 Set the version of the extended attribute blocks
121 which e2fsck will require while checking the
122 filesystem. The version number may be 1 or 2. The
123 default extended attribute version format is 2.
124 journal_only
126 Only replay the journal if required, but do not per‐
127 form any further checks or repairs.
128 fragcheck
130 During pass 1, print a detailed report of any dis‐
131 contiguous blocks for files in the filesystem.
132 discard
134 Attempt to discard free blocks and unused inode
135 blocks after the full filesystem check (discarding
136 blocks is useful on solid state devices and sparse /
137 thin-provisioned storage). Note that discard is done
138 in pass 5 AFTER the filesystem has been fully
139 checked and only if it does not contain recognizable
140 errors. However there might be cases where e2fsck
141 does not fully recognize a problem and hence in this
142 case this option may prevent you from further manual
143 data recovery.
144 nodiscard
146 Do not attempt to discard free blocks and unused
147 inode blocks. This option is exactly the opposite of
148 discard option. This is set as default.
149 no_optimize_extents
151 Do not offer to optimize the extent tree by elimi‐
152 nating unnecessary width or depth. This can also be
153 enabled in the options section of /etc/e2fsck.conf.
154 optimize_extents
156 Offer to optimize the extent tree by eliminating
157 unnecessary width or depth. This is the default
158 unless otherwise specified in /etc/e2fsck.conf.
159 inode_count_fullmap
161 Trade off using memory for speed when checking a
162 file system with a large number of hard-linked
163 files. The amount of memory required is propor‐
164 tional to the number of inodes in the file system.
165 For large file systems, this can be gigabytes of
166 memory. (For example, a 40TB file system with 2.8
167 billion inodes will consume an additional 5.7 GB
168 memory if this optimization is enabled.) This opti‐
169 mization can also be enabled in the options section
170 of /etc/e2fsck.conf.
171 no_inode_count_fullmap
173 Disable the inode_count_fullmap optimization. This
174 is the default unless otherwise specified in
175 /etc/e2fsck.conf.
176 readahead_kb
178 Use this many KiB of memory to pre-fetch metadata in
179 the hopes of reducing e2fsck runtime. By default,
180 this is set to the size of two block groups' inode
181 tables (typically 4MiB on a regular ext4 filesys‐
182 tem); if this amount is more than 1/50th of total
183 physical memory, readahead is disabled. Set this to
184 zero to disable readahead entirely.
185 bmap2extent
187 Convert block-mapped files to extent-mapped files.
188 fixes_only
190 Only fix damaged metadata; do not optimize htree
191 directories or compress extent trees. This option
192 is incompatible with the -D and -E bmap2extent
193 options.
194 unshare_blocks
196 If the filesystem has shared blocks, with the shared
197 blocks read-only feature enabled, then this will
198 unshare all shared blocks and unset the read-only
199 feature bit. If there is not enough free space then
200 the operation will fail. If the filesystem does not
201 have the read-only feature bit, but has shared
202 blocks anyway, then this option will have no effect.
203 Note when using this option, if there is no free
204 space to clone blocks, there is no prompt to delete
205 files and instead the operation will fail.
206 Note that unshare_blocks implies the "-f" option to
208 ensure that all passes are run. Additionally, if
209 "-n" is also specified, e2fsck will simulate trying
210 to allocate enough space to deduplicate. If this
211 fails, the exit code will be non-zero.
212 -f Force checking even if the file system seems clean.
214 -F Flush the filesystem device's buffer caches before beginning.
216 Only really useful for doing e2fsck time trials.
217 -j external-journal
219 Set the pathname where the external-journal for this filesystem
220 can be found.
221 -k When combined with the -c option, any existing bad blocks in the
223 bad blocks list are preserved, and any new bad blocks found by
224 running badblocks(8) will be added to the existing bad blocks
225 list.
226 -l filename
228 Add the block numbers listed in the file specified by filename
229 to the list of bad blocks. The format of this file is the same
230 as the one generated by the badblocks(8) program. Note that the
231 block numbers are based on the blocksize of the filesystem.
232 Hence, badblocks(8) must be given the blocksize of the filesys‐
233 tem in order to obtain correct results. As a result, it is much
234 simpler and safer to use the -c option to e2fsck, since it will
235 assure that the correct parameters are passed to the badblocks
236 program.
237 -L filename
239 Set the bad blocks list to be the list of blocks specified by
240 filename. (This option is the same as the -l option, except the
241 bad blocks list is cleared before the blocks listed in the file
242 are added to the bad blocks list.)
243 -n Open the filesystem read-only, and assume an answer of `no' to
245 all questions. Allows e2fsck to be used non-interactively.
246 This option may not be specified at the same time as the -p or
247 -y options.
248 -p Automatically repair ("preen") the file system. This option
250 will cause e2fsck to automatically fix any filesystem problems
251 that can be safely fixed without human intervention. If e2fsck
252 discovers a problem which may require the system administrator
253 to take additional corrective action, e2fsck will print a
254 description of the problem and then exit with the value 4 logi‐
255 cally or'ed into the exit code. (See the EXIT CODE section.)
256 This option is normally used by the system's boot scripts. It
257 may not be specified at the same time as the -n or -y options.
258 -r This option does nothing at all; it is provided only for back‐
260 wards compatibility.
261 -t Print timing statistics for e2fsck. If this option is used
263 twice, additional timing statistics are printed on a pass by
264 pass basis.
265 -v Verbose mode.
267 -V Print version information and exit.
269 -y Assume an answer of `yes' to all questions; allows e2fsck to be
271 used non-interactively. This option may not be specified at the
272 same time as the -n or -p options.
273 -z undo_file
275 Before overwriting a file system block, write the old contents
276 of the block to an undo file. This undo file can be used with
277 e2undo(8) to restore the old contents of the file system should
278 something go wrong. If the empty string is passed as the
279 undo_file argument, the undo file will be written to a file
280 named e2fsck-device.e2undo in the directory specified via the
281 E2FSPROGS_UNDO_DIR environment variable.
282 WARNING: The undo file cannot be used to recover from a power or
284 system crash.
285
287 The exit code returned by e2fsck is the sum of the following condi‐
288 tions:
289 0 - No errors
290 1 - File system errors corrected
291 2 - File system errors corrected, system should
292 be rebooted
293 4 - File system errors left uncorrected
294 8 - Operational error
295 16 - Usage or syntax error
296 32 - E2fsck canceled by user request
297 128 - Shared library error
298
300 The following signals have the following effect when sent to e2fsck.
301 SIGUSR1
303 This signal causes e2fsck to start displaying a completion bar
304 or emitting progress information. (See discussion of the -C
305 option.)
306 SIGUSR2
308 This signal causes e2fsck to stop displaying a completion bar or
309 emitting progress information.
310
312 Almost any piece of software will have bugs. If you manage to find a
313 filesystem which causes e2fsck to crash, or which e2fsck is unable to
314 repair, please report it to the author.
315 Please include as much information as possible in your bug report.
317 Ideally, include a complete transcript of the e2fsck run, so I can see
318 exactly what error messages are displayed. (Make sure the messages
319 printed by e2fsck are in English; if your system has been configured so
320 that e2fsck's messages have been translated into another language,
321 please set the the LC_ALL environment variable to C so that the tran‐
322 script of e2fsck's output will be useful to me.) If you have a
323 writable filesystem where the transcript can be stored, the script(1)
324 program is a handy way to save the output of e2fsck to a file.
325 It is also useful to send the output of dumpe2fs(8). If a specific
327 inode or inodes seems to be giving e2fsck trouble, try running the
328 debugfs(8) command and send the output of the stat(1u) command run on
329 the relevant inode(s). If the inode is a directory, the debugfs dump
330 command will allow you to extract the contents of the directory inode,
331 which can sent to me after being first run through uuencode(1). The
332 most useful data you can send to help reproduce the bug is a compressed
333 raw image dump of the filesystem, generated using e2image(8). See the
334 e2image(8) man page for more details.
335 Always include the full version string which e2fsck displays when it is
337 run, so I know which version you are running.
338
340 E2FSCK_CONFIG
341 Determines the location of the configuration file (see
342 e2fsck.conf(5)).
343
345 This version of e2fsck was written by Theodore Ts'o <tytso@mit.edu>.
346
348 e2fsck.conf(5), badblocks(8), dumpe2fs(8), debugfs(8), e2image(8),
349 mke2fs(8), tune2fs(8)
350E2fsprogs version 1.45.5 January 2020 E2FSCK(8)