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29 .\" @(#)fsck.8 8.4 (Berkeley) 5/9/95
38 .Nd file system consistency check and interactive repair
48 The specified disk partitions and/or file systems are checked.
49 In "preen" or "check clean" mode the clean flag of each file system's
50 superblock is examined and only those file systems that are not marked clean
52 File systems are marked clean when they are unmounted,
53 when they have been mounted read-only, or when
55 runs on them successfully.
58 option is specified, the file systems
59 will be checked regardless of the state of their clean flag.
61 The kernel takes care that only a restricted class of innocuous file system
62 inconsistencies can happen unless hardware or software failures intervene.
63 These are limited to the following:
65 .Bl -item -compact -offset indent
69 Link counts in inodes too large
71 Missing blocks in the free map
73 Blocks in the free map also in files
75 Counts in the super-block wrong
78 These are the only inconsistencies that
82 option will correct; if it encounters other inconsistencies, it exits
83 with an abnormal return status and an automatic reboot will then fail.
84 For each corrected inconsistency one or more lines will be printed
85 identifying the file system on which the correction will take place,
86 and the nature of the correction.
87 After successfully correcting a file system,
89 will print the number of files on that file system,
90 the number of used and free blocks,
91 and the percentage of fragmentation.
97 will finish the file system checks, then exit with an abnormal
98 return status that causes an automatic reboot to fail.
99 This is useful when you want to finish the file system checks during an
101 but do not want the machine to come up multiuser after the checks complete.
111 signal, a line will be written to the standard output indicating
112 the name of the device currently being checked, the current phase
113 number and phase-specific progress information.
119 audits and interactively repairs inconsistent conditions for file systems.
120 If the file system is inconsistent the operator is prompted for concurrence
121 before each correction is attempted.
122 It should be noted that some of the corrective actions which are not
123 correctable under the
125 option will result in some loss of data.
126 The amount and severity of data lost may be determined from the diagnostic
128 The default action for each consistency correction
129 is to wait for the operator to respond
133 If the operator does not have write permission on the file system
139 The following flags are interpreted by
141 .Bl -tag -width indent
143 A check is done on the specified and possibly active file system.
144 The set of corrections that can be done is limited to those done
145 when running in preen mode (see the
148 If unexpected errors are found,
149 the file system is marked as needing a foreground check and
151 exits without attempting any further cleaning.
153 Clear unallocated blocks, notifying the underlying device that they
154 are not used and that their contents may be discarded.
155 This is useful for filesystems which have been mounted on systems
156 without TRIM support, or with TRIM support disabled, as well as
157 filesystems which have been copied from one device to another.
171 Determine whether the file system needs to be cleaned immediately
172 in foreground, or if its cleaning can be deferred to background.
173 To be eligible for background cleaning it must have been running
174 with soft updates, not have been marked as needing a foreground check,
175 and be mounted and writable when the background check is to be done.
176 If these conditions are met, then
178 exits with a zero exit status.
179 Otherwise it exits with a non-zero exit status.
180 If the file system is clean,
181 it will exit with a non-zero exit status so that the clean status
182 of the file system can be verified and reported during the foreground
184 Note that when invoked with the
186 flag, no cleanups are done.
189 does is to determine whether a foreground or background
190 check is needed and exit with an appropriate status code.
192 Use the block specified immediately after the flag as
193 the super block for the file system.
194 An alternate super block is usually located at block 32 for UFS1,
195 and block 160 for UFS2.
202 Check if file system was dismounted cleanly.
203 If so, skip file system checks (like "preen").
204 However, if the file system was not cleanly dismounted, do full checks,
210 Convert the file system to the specified level.
211 Note that the level of a file system can only be raised.
212 There are currently four levels defined:
213 .Bl -tag -width indent
215 The file system is in the old (static table) format.
217 The file system is in the new (dynamic table) format.
219 The file system supports 32-bit uid's and gid's,
220 short symbolic links are stored in the inode,
221 and directories have an added field showing the file type.
223 If maxcontig is greater than one,
224 build the free segment maps to aid in finding contiguous sets of blocks.
225 If maxcontig is equal to one, delete any existing segment maps.
230 will list the conversion to be made
231 and ask whether the conversion should be done.
232 If a negative answer is given,
233 no further operations are done on the file system.
235 the conversion is listed and done if
236 possible without user interaction.
237 Conversion in preen mode is best used when all the file systems
238 are being converted at once.
239 The format of a file system can be determined from the
240 first line of output from
243 This option implies the
251 file systems when preening.
253 Use the mode specified in octal immediately after the flag as the
254 permission bits to use when creating the
256 directory rather than the default 1777.
257 In particular, systems that do not wish to have lost files accessible
258 by all users on the system should use a more restrictive
259 set of permissions such as 700.
261 Assume a no response to all questions asked by
265 which is assumed to be affirmative;
266 do not open the file system for writing.
268 Preen file systems (see above).
270 Instruct fsck_ffs to restart itself if it encounters certain errors that
271 warrant another run. It will limit itself to a maximum of 10 restarts
272 in a given run in order to avoid an endless loop with extremely corrupted
275 Free up excess unused inodes.
276 Decreasing the number of preallocated inodes reduces the
277 running time of future runs of
279 and frees up space that can allocated to files.
282 option is ignored when running in preen mode.
285 With this flag enabled, a hard error returned on disk i/o will cause
287 to abort instead of continuing on and possibly tripping over more i/o errors.
289 Assume a yes response to all questions asked by
291 this should be used with great caution as this is a free license
292 to continue after essentially unlimited trouble has been encountered.
296 but overwrites unused blocks with zeroes.
301 are specified, blocks are first zeroed and then erased.
304 Inconsistencies checked are as follows:
308 Blocks claimed by more than one inode or the free map.
310 Blocks claimed by an inode outside the range of the file system.
312 Incorrect link counts.
315 .Bl -item -offset indent -compact
317 Directory size not a multiple of DIRBLKSIZ.
319 Partially truncated file.
324 Blocks not accounted for anywhere.
327 .Bl -item -offset indent -compact
329 File pointing to unallocated inode.
331 Inode number out of range.
333 Directories with unallocated blocks (holes).
335 Dot or dot-dot not the first two entries of a directory
336 or having the wrong inode number.
340 .Bl -item -offset indent -compact
342 More blocks for inodes than there are in the file system.
344 Bad free block map format.
346 Total free block and/or free inode count incorrect.
350 Orphaned files and directories (allocated but unreferenced) are,
351 with the operator's concurrence, reconnected by
355 The name assigned is the inode number.
358 directory does not exist, it is created.
359 If there is insufficient space its size is increased.
363 checks for many more problems that may occur after an
364 unrecoverable disk write error.
365 Thus, it is recommended that you perform foreground
367 on your systems periodically and whenever you encounter
368 unrecoverable disk write errors or file-system\-related panics.
370 .Bl -tag -width /etc/fstab -compact
372 contains default list of file systems to check.
381 exits 7 if the file system is clean.
383 The diagnostics produced by
385 are fully enumerated and explained in Appendix A of
387 .%T "Fsck \- The UNIX File System Check Program"