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 FSCK 8 "February 2009" "Linux" "MAINTENANCE COMMANDS"
7 fsck \- check and repair a Linux file system
17 .RI [ fs-specific-options ]
20 is used to check and optionally repair one or more Linux file systems.
22 can be a device name (e.g.
23 .IR /dev/hdc1 ", " /dev/sdb2 ),
25 .IR / ", " /usr ", " /home ),
26 or an ext2 label or UUID specifier (e.g.
27 UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd or LABEL=root).
30 program will try to handle filesystems on different physical disk drives
31 in parallel to reduce the total amount of time needed to check all of the
34 If no filesystems are specified on the command line, and the
36 option is not specified,
38 will default to checking filesystems in
40 serially. This is equivalent to the
44 The exit code returned by
46 is the sum of the following conditions:
50 \ 1\ \-\ File system errors corrected
52 \ 2\ \-\ System should be rebooted
54 \ 4\ \-\ File system errors left uncorrected
56 \ 8\ \-\ Operational error
58 \ 16\ \-\ Usage or syntax error
60 \ 32\ \-\ Fsck canceled by user request
62 \ 128\ \-\ Shared library error
64 The exit code returned when multiple file systems are checked
65 is the bit-wise OR of the exit codes for each
66 file system that is checked.
70 is simply a front-end for the various file system checkers
71 (\fBfsck\fR.\fIfstype\fR) available under Linux. The file
72 system-specific checker is searched for in
78 and finally in the directories listed in the PATH environment
79 variable. Please see the file system-specific checker manual pages for
86 operations. This is a good idea if you are checking multiple
87 filesystems and the checkers are in an interactive mode. (Note:
89 runs in an interactive mode by default. To make
91 run in a non-interactive mode, you must either specify the
95 option, if you wish for errors to be corrected automatically, or the
97 option if you do not.)
100 Specifies the type(s) of file system to be checked. When the
102 flag is specified, only filesystems that match
106 parameter is a comma-separated list of filesystems and options
107 specifiers. All of the filesystems in this comma-separated list may be
108 prefixed by a negation operator
112 which requests that only those filesystems not listed in
114 will be checked. If all of the filesystems in
116 are not prefixed by a negation operator, then only those filesystems
122 Options specifiers may be included in the comma-separated
124 They must have the format
125 .BI opts= fs-option\fR.
126 If an options specifier is present, then only filesystems which contain
128 in their mount options field of
130 will be checked. If the options specifier is prefixed by a negation
132 those filesystems that do not have
134 in their mount options field of
142 then only filesystems listed in
146 option will be checked.
148 For compatibility with Mandrake distributions whose boot scripts
149 depend upon an unauthorized UI change to the
151 program, if a filesystem type of
157 were specified as an argument to the
161 Normally, the filesystem type is deduced by searching for
165 file and using the corresponding entry.
166 If the type can not be deduced, and there is only a single filesystem
167 given as an argument to the
171 will use the specified filesystem type. If this type is not
172 available, then the default file system type (currently ext2) is used.
177 file and try to check all file systems in one run. This option is
178 typically used from the
180 system initialization file, instead of multiple commands for checking
181 a single file system.
183 The root filesystem will be checked first unless the
185 option is specified (see below). After that,
186 filesystems will be checked in the order specified by the
188 (the sixth) field in the
193 value of 0 are skipped and are not checked at all. Filesystems with a
195 value of greater than zero will be checked in order,
196 with filesystems with the lowest
198 number being checked first.
199 If there are multiple filesystems with the same pass number,
200 fsck will attempt to check them in parallel, although it will avoid running
201 multiple filesystem checks on the same physical disk.
203 Hence, a very common configuration in
205 files is to set the root filesystem to have a
208 and to set all other filesystems to have a
210 value of 2. This will allow
212 to automatically run filesystem checkers in parallel if it is advantageous
213 to do so. System administrators might choose
214 not to use this configuration if they need to avoid multiple filesystem
215 checks running in parallel for some reason --- for example, if the
216 machine in question is short on memory so that
217 excessive paging is a concern.
219 .B \-C\fR [ \fI "fd" \fR ]
220 Display completion/progress bars for those filesystem checkers (currently
221 only for ext2 and ext3) which support them. Fsck will manage the
222 filesystem checkers so that only one of them will display
223 a progress bar at a time. GUI front-ends may specify a file descriptor
225 in which case the progress bar information will be sent to that file descriptor.
228 Do not check mounted filesystems and return an exit code of 0
229 for mounted filesystems.
232 Don't execute, just show what would be done.
237 flag is set, check the root filesystem in parallel with the other filesystems.
238 This is not the safest thing in the world to do,
239 since if the root filesystem is in doubt things like the
241 executable might be corrupted! This option is mainly provided
242 for those sysadmins who don't want to repartition the root
243 filesystem to be small and compact (which is really the right solution).
246 When checking all file systems with the
248 flag, skip the root file system (in case it's already mounted read-write).
251 Don't show the title on startup.
254 Produce verbose output, including all file system-specific commands
257 .B fs-specific-options
258 Options which are not understood by
260 are passed to the filesystem-specific checker. These arguments
262 not take arguments, as there is no
265 to be able to properly guess which arguments take options and which
268 Options and arguments which follow the
270 are treated as file system-specific options to be passed to the
271 file system-specific checker.
273 Please note that fsck is not
274 designed to pass arbitrarily complicated options to filesystem-specific
275 checkers. If you're doing something complicated, please just
276 execute the filesystem-specific checker directly. If you pass
278 some horribly complicated option and arguments, and it doesn't do
280 .B don't bother reporting it as a bug.
281 You're almost certainly doing something that you shouldn't be doing
285 Options to different filesystem-specific fsck's are not standardized.
286 If in doubt, please consult the man pages of the filesystem-specific
287 checker. Although not guaranteed, the following options are supported
288 by most file system checkers:
291 Automatically repair the file system without any questions (use
292 this option with caution). Note that
296 for backwards compatibility only. This option is mapped to
299 option which is safe to use, unlike the
301 option that some file system checkers support.
304 For some filesystem-specific checkers, the
306 option will cause the fs-specific fsck to avoid attempting to repair any
307 problems, but simply report such problems to stdout. This is however
308 not true for all filesystem-specific checkers. In particular,
309 .BR fsck.reiserfs (8)
310 will not report any corruption if given this option.
317 Interactively repair the filesystem (ask for confirmations). Note: It
318 is generally a bad idea to use this option if multiple fsck's are being
319 run in parallel. Also note that this is
321 default behavior; it supports this option for backwards compatibility
325 For some filesystem-specific checkers, the
327 option will cause the fs-specific fsck to always attempt to fix any
328 detected filesystem corruption automatically. Sometimes an expert may
329 be able to do better driving the fsck manually. Note that
331 all filesystem-specific checkers implement this option. In particular
337 option as of this writing.
339 Theodore Ts'o (tytso@mit.edu)
341 The blkid command is part of the util-linux-ng package and is available from
342 ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
345 .SH ENVIRONMENT VARIABLES
348 program's behavior is affected by the following environment variables:
350 .B FSCK_FORCE_ALL_PARALLEL
351 If this environment variable is set,
353 will attempt to run all of the specified filesystems in parallel,
354 regardless of whether the filesystems appear to be on the same
355 device. (This is useful for RAID systems or high-end storage systems
356 such as those sold by companies such as IBM or EMC.)
359 This environment variable will limit the maximum number of file system
360 checkers that can be running at one time. This allows configurations
361 which have a large number of disks to avoid
363 starting too many file system checkers at once, which might overload
364 CPU and memory resources available on the system. If this value is
365 zero, then an unlimited number of processes can be spawned. This is
366 currently the default, but future versions of
368 may attempt to automatically determine how many file system checks can
369 be run based on gathering accounting data from the operating system.
374 environment variable is used to find file system checkers. A set of
375 system directories are searched first:
382 Then the set of directories found in the
384 environment are searched.
387 This environment variable allows the system administrator
388 to override the standard location of the
390 file. It is also useful for developers who are testing
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