Section (8) fsck
fsck — check and repair a Linux filesystem
−r [fd] ] [
−C [fd] ] [
−t fstype ] [ filesystem... ]
fsck is used
to check and optionally repair one or more Linux filesystems.
filesys can be
a device name (e.g.
/dev/sdb2), a mount point (e.g.
or an ext2 label or UUID specifier (e.g.
UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd or LABEL=root).
Normally, the fsck program will try to
handle filesystems on different physical disk drives in
parallel to reduce the total amount of time needed to check
all of them.
If no filesystems are specified on the command line, and
−A option is not
will default to checking filesystems in
/etc/fstab serially. This is equivalent to
The exit code returned by fsck is the sum of the following conditions:
Filesystem errors corrected
System should be rebooted
Filesystem errors left uncorrected
Usage or syntax error
Checking canceled by user request
The exit code returned when multiple filesystems are checked is the bit-wise OR of the exit codes for each filesystem that is checked.
In actuality, fsck is simply a front-end
for the various filesystem checkers (fsck.
fstype) available under Linux.
The filesystem-specific checker is searched for in the PATH
environment variable. If the PATH is undefined then fallback
Please see the filesystem-specific checker manual pages for further details.
Create an exclusive flock(2) lock file (/run/fsck/<diskname>.lock) for whole-disk device. This option can be used with one device only (this means that
−lare mutually exclusive). This option is recommended when more fsck(8) instances are executed in the same time. The option is ignored when used for multiple devices or for non-rotating disks. fsck does not lock underlying devices when executed to check stacked devices (e.g. MD or DM) – this feature is not implemented yet.
Report certain statistics for each fsck when it completes. These statistics include the exit status, the maximum run set size (in kilobytes), the elapsed all-clock time and the user and system CPU time used by the fsck run. For example:
/dev/sda1: status 0, rss 92828, real 4.002804, user 2.677592, sys 0.86186
GUI front-ends may specify a file descriptor
fd, in which case the progress bar information will be sent to that file descriptor in a machine parsable format. For example:
/dev/sda1 0 92828 4.002804 2.677592 0.86186
Serialize fsck operations. This is a good idea if you are checking multiple filesystems and the checkers are in an interactive mode.
e2fsck(8) runs in an interactive mode by default. To make e2fsck(8) run in a non-interactive mode, you must either specify the
−aoption, if you wish for errors to be corrected automatically, or the
−noption if you do not.
Specifies the type(s) of filesystem to be checked. When the
−Aflag is specified, only filesystems that match fslist are checked. The fslist parameter is a comma-separated list of filesystems and options specifiers. All of the filesystems in this comma-separated list may be prefixed by a negation operator _zsingle_quotesz_no_zsingle_quotesz_ or _zsingle_quotesz_
!_zsingle_quotesz_, which requests that only those filesystems not listed in fslist will be checked. If none of the filesystems in fslist is prefixed by a negation operator, then only those listed filesystems will be checked.
Options specifiers may be included in the comma-separated fslist. They must have the format
fs-option. If an options specifier is present, then only filesystems which contain
fs-optionin their mount options field of
/etc/fstabwill be checked. If the options specifier is prefixed by a negation operator, then only those filesystems that do not have
fs-optionin their mount options field of
/etc/fstabwill be checked.
For example, if
opts=roappears in fslist, then only filesystems listed in
/etc/fstabwith the ro option will be checked.
For compatibility with Mandrake distributions whose boot scripts depend upon an unauthorized UI change to the fsck program, if a filesystem type of loop is found in fslist, it is treated as if
opts=loopwere specified as an argument to the
Normally, the filesystem type is deduced by searching for filesys in the
/etc/fstabfile and using the corresponding entry. If the type cannot be deduced, and there is only a single filesystem given as an argument to the
−toption, fsck will use the specified filesystem type. If this type is not available, then the default filesystem type (currently ext2) is used.
Walk through the
/etc/fstabfile and try to check all filesystems in one run. This option is typically used from the
/etc/rcsystem initialization file, instead of multiple commands for checking a single filesystem.
The root filesystem will be checked first unless the
−Poption is specified (see below). After that, filesystems will be checked in the order specified by the fs_passno (the sixth) field in the
/etc/fstabfile. Filesystems with a fs_passno value of 0 are skipped and are not checked at all. Filesystems with a fs_passno value of greater than zero will be checked in order, with filesystems with the lowest fs_passno number being checked first. If there are multiple filesystems with the same pass number, fsck will attempt to check them in parallel, although it will avoid running multiple filesystem checks on the same physical disk.
fsck does not check stacked devices (RAIDs, dm-crypt, ...) in parallel with any other device. See below for FSCK_FORCE_ALL_PARALLEL setting. The /sys filesystem is used to determine dependencies between devices.
Hence, a very common configuration in
/etc/fstabfiles is to set the root filesystem to have a fs_passno value of 1 and to set all other filesystems to have a fs_passno value of 2. This will allow fsck to automatically run filesystem checkers in parallel if it is advantageous to do so. System administrators might choose not to use this configuration if they need to avoid multiple filesystem checks running in parallel for some reason – for example, if the machine in question is short on memory so that excessive paging is a concern.
fsck normally does not check whether the device actually exists before calling a filesystem specific checker. Therefore non-existing devices may cause the system to enter filesystem repair mode during boot if the filesystem specific checker returns a fatal error. The
/etc/fstabmount option nofail may be used to have fsck skip non-existing devices. fsck also skips non-existing devices that have the special filesystem type auto.
−C[ fd ]
Display completion/progress bars for those filesystem checkers (currently only for ext) which support them. fsck will manage the filesystem checkers so that only one of them will display a progress bar at a time. GUI front-ends may specify a file descriptor
fd, in which case the progress bar information will be sent to that file descriptor.
Do not check mounted filesystems and return an exit code of 0 for mounted filesystems.
Don_zsingle_quotesz_t execute, just show what would be done.
−Aflag is set, check the root filesystem in parallel with the other filesystems. This is not the safest thing in the world to do, since if the root filesystem is in doubt things like the e2fsck(8) executable might be corrupted! This option is mainly provided for those sysadmins who don_zsingle_quotesz_t want to repartition the root filesystem to be small and compact (which is really the right solution).
When checking all filesystems with the
−Aflag, skip the root filesystem. (This is useful in case the root filesystem has already been mounted read-write.)
Don_zsingle_quotesz_t show the title on startup.
Produce verbose output, including all filesystem-specific commands that are executed.
Display help text and exit.
Display version information and exit.
FILESYSTEM SPECIFIC OPTIONS
Options which are not understood by fsck are passed to the filesystem-specific checker!
These options must not take arguments, as there is no way for fsck to be able to properly guess which options take arguments and which don_zsingle_quotesz_t.
Options and arguments which follow the
−− are treated as
filesystem-specific options to be passed to the
Please note that fsck is not designed to pass arbitrarily complicated options to filesystem-specific checkers. If you_zsingle_quotesz_re doing something complicated, please just execute the filesystem-specific checker directly. If you pass fsck some horribly complicated options and arguments, and it doesn_zsingle_quotesz_t do what you expect, don_zsingle_quotesz_t bother reporting it as a bug. You_zsingle_quotesz_re almost certainly doing something that you shouldn_zsingle_quotesz_t be doing with fsck. Options to different filesystem-specific fsck_zsingle_quotesz_s are not standardized.
The fsck program_zsingle_quotesz_s behavior is affected by the following environment variables:
If this environment variable is set, fsck will attempt to check all of the specified filesystems in parallel, regardless of whether the filesystems appear to be on the same device. (This is useful for RAID systems or high-end storage systems such as those sold by companies such as IBM or EMC.) Note that the fs_passno value is still used.
This environment variable will limit the maximum number of filesystem checkers that can be running at one time. This allows configurations which have a large number of disks to avoid fsck starting too many filesystem checkers at once, which might overload CPU and memory resources available on the system. If this value is zero, then an unlimited number of processes can be spawned. This is currently the default, but future versions of fsck may attempt to automatically determine how many filesystem checks can be run based on gathering accounting data from the operating system.
PATHenvironment variable is used to find filesystem checkers.
This environment variable allows the system administrator to override the standard location of the
/etc/fstabfile. It is also useful for developers who are testing fsck.
enables libblkid debug output.
enables libmount debug output.
The fsck command is part of the util-linux package and is available from Linux Kernel Archive
Copyright 1993, 1994, 1995 by Theodore Ts_zsingle_quotesz_o. All Rights Reserved.
This file may be copied under the terms of the GNU Public License.