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FSCK(8) FSCK(8)
NAME
fsck - check and repair a Linux file system
SYNOPSIS
fsck [ -sAVRTNP ] [ -C [ fd ] ] [ -t fstype ] [filesys ... ] [--] [ fs-specific-
options ]
DESCRIPTION
fsck is used to check and optionally repair one or more Linux file systems.
filesys can be a device name (e.g. /dev/hdc1, /dev/sdb2), a mount point (e.g. /,
/usr, /home), or an ext2 label or UUID specifier (e.g.
UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd or LABEL=root). Normally, the fsck pro-
gram will try to handle filesystems on different physical disk drives in parallel
to reduce the total amount of time needed to check all of the filesystems.
If no filesystems are specified on the command line, and the -A option is not spec-
ified, fsck will default to checking filesystems in /etc/fstab serially. This is
equivalent to the -As options.
The exit code returned by fsck is the sum of the following conditions:
0 - No errors
1 - File system errors corrected
2 - System should be rebooted
4 - File system errors left uncorrected
8 - Operational error
16 - Usage or syntax error
32 - Fsck canceled by user request
128 - Shared library error
The exit code returned when multiple file systems are checked is the bit-wise OR of
the exit codes for each file system that is checked.
In actuality, fsck is simply a front-end for the various file system checkers
(fsck.fstype) available under Linux. The file system-specific checker is searched
for in /sbin first, then in /etc/fs and /etc, and finally in the directories listed
in the PATH environment variable. Please see the file system-specific checker man-
ual pages for further details.
OPTIONS
-s Serialize fsck operations. This is a good idea if you are checking multiple
filesystems and the checkers are in an interactive mode. (Note: e2fsck(8)
runs in an interactive mode by default. To make e2fsck(8) run in a non-
interactive mode, you must either specify the -p or -a option, if you wish
for errors to be corrected automatically, or the -n option if you do not.)
-t fslist
Specifies the type(s) of file system to be checked. When the -A flag 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 ’no’ or ’!’, which requests that only those filesystems
not listed in fslist will be checked. If all of the filesystems in fslist
are not prefixed by a negation operator, then only those filesystems listed
in fslist will be checked.
Options specifiers may be included in the comma-separated fslist. They must
have the format opts=fs-option. If an options specifier is present, then
only filesystems which contain fs-option in their mount options field of
/etc/fstab will be checked. If the options specifier is prefixed by a nega-
tion operator, then only those filesystems that do not have fs-option in
their mount options field of /etc/fstab will be checked.
For example, if opts=ro appears in fslist, then only filesystems listed in
/etc/fstab with 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=loop were specified as an argu-
ment to the -t option.
Normally, the filesystem type is deduced by searching for filesys in the
/etc/fstab file and using the corresponding entry. If the type can not be
deduced, and there is only a single filesystem given as an argument to the
-t option, fsck will use the specified filesystem type. If this type is not
available, then the default file system type (currently ext2) is used.
-A Walk through the /etc/fstab file and try to check all file systems in one
run. This option is typically used from the /etc/rc system initialization
file, instead of multiple commands for checking a single file system.
The root filesystem will be checked first unless the -P option is specified
(see below). After that, filesystems will be checked in the order specified
by the fs_passno (the sixth) field in the /etc/fstab file. 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.
Hence, a very common configuration in /etc/fstab files 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.
-C [ fd ]
Display completion/progress bars for those filesystem checkers (currently
only for ext2 and ext3) which support them. Fsck will manage the filesys-
tem 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.
-N Don’t execute, just show what would be done.
-P When the -A flag 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’t want to repartition the root filesystem to be small and compact (which
is really the right solution).
-R When checking all file systems with the -A flag, skip the root file system
(in case it’s already mounted read-write).
-T Don’t show the title on startup.
-V Produce verbose output, including all file system-specific commands that are
executed.
fs-specific-options
Options which are not understood by fsck are passed to the filesystem-spe-
cific checker. These arguments must not take arguments, as there is no way
for fsck to be able to properly guess which arguments take options and which
don’t.
Options and arguments which follow the -- are treated as file system-spe-
cific options to be passed to the file system-specific checker.
Please note that fsck is not designed to pass arbitrarily complicated
options to filesystem-specific checkers. If you’re doing something compli-
cated, please just execute the filesystem-specific checker directly. If you
pass fsck some horribly complicated option and arguments, and it doesn’t do
what you expect, donâ€â€™t bother reporting it as a bug. You’re almost cer-
tainly doing something that you shouldn’t be doing with fsck.
Options to different filesystem-specific fsck’s are not standardized. If in doubt,
please consult the man pages of the filesystem-specific checker. Although not
guaranteed, the following options are supported by most file system checkers:
-a Automatically repair the file system without any questions (use this option
with caution). Note that e2fsck(8) supports -a for backwards compatibility
only. This option is mapped to e2fsck’s -p option which is safe to use,
unlike the -a option that some file system checkers support.
-n For some filesystem-specific checkers, the -n option will cause the fs-spe-
cific fsck to avoid attempting to repair any problems, but simply report
such problems to stdout. This is however not true for all filesystem-spe-
cific checkers. In particular, fsck.reiserfs(8) will not report any corrup-
tion if given this option. fsck.minix(8) does not support the -n option at
all.
-r Interactively repair the filesystem (ask for confirmations). Note: It is
generally a bad idea to use this option if multiple fsck’s are being run in
parallel. Also note that this is e2fsck’s default behavior; it supports
this option for backwards compatibility reasons only.
-y For some filesystem-specific checkers, the -y option will cause the fs-spe-
cific fsck to always attempt to fix any detected filesystem corruption auto-
matically. Sometimes an expert may be able to do better driving the fsck
manually. Note that not all filesystem-specific checkers implement this
option. In particular fsck.minix(8) and fsck.cramfs(8) does not support the
-y option as of this writing.
AUTHOR
Theodore Ts’o (tytso AT mit.edu)
FILES
/etc/fstab.
ENVIRONMENT VARIABLES
The fsck program’s behavior is affected by the following environment variables:
FSCK_FORCE_ALL_PARALLEL
If this environment variable is set, fsck will attempt to run 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.)
FSCK_MAX_INST
This environment variable will limit the maximum number of file system
checkers that can be running at one time. This allows configurations which
have a large number of disks to avoid fsck starting too many file system
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 file system checks can be
run based on gathering accounting data from the operating system.
PATH The PATH environment variable is used to find file system checkers. A set
of system directories are searched first: /sbin, /sbin/fs.d, /sbin/fs,
/etc/fs, and /etc. Then the set of directories found in the PATH
environment are searched.
FSTAB_FILE
This environment variable allows the system administrator to override the
standard location of the /etc/fstab file. It is also useful for developers
who are testing fsck.
SEE ALSO
fstab(5), mkfs(8), fsck.ext2(8) or e2fsck(8), cramfsck(8) fsck.minix(8),
fsck.jfs(8) fsck.xfs(8), fsck.xiafs(8) reiserfsck(8).
E2fsprogs version 1.38 June 2005 FSCK(8)
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On Apache/1.3.41 (Unix) PHP/5.2.5 mod_perl/1.30 mod_gzip/1.3.26.1a
Under GNU General Public License
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