fsck
SYNOPSIS
fsck [ -sACVRTNP ] [ -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 program will try to run filesystems on
different physical disk drives in parallel to reduce total
amount time to check all of the filesystems.
If no filesystems are specified on the command line, and
the -A option is not specified, fsck will default to
checking filesystems in /etc/fstab serial. This is equiv
alent 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 direc
tories listed in the PATH environment variable. Please
see the file system-specific checker manual pages for fur
ther 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
opts=fs-option. If an options specifier is pre
sent, 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
negation 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 argument to the -t option.
Normally, the filesystem type is deduced by search
ing 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 typi
cally used from the /etc/rc system initalization
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 multi
ple 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 filesystems to
have a fs_passno value of 2. This will allow fsck
to automatically run filesystem checkers in paral
-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 solu
tion).
-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-specific checker. These argu
ments must not take arguments, as there is no way
for fsck to be able to properly guess which argu
ments take options and which don't.
Options and arguments which follow the -- are
treated as file system-specific options to be
passed to the file system-specific checker.
Please note that fsck is not designed to pass arbi
trarily complicated options to filesystem-specific
checkers. If you're doing something complicated,
please just execute the filesystem-specific checker
directly. If you pass fsck some horribly compli
cated option and arguments, and it doesn't do what
you expect, don't bother reporting it as a bug.
You're almost certainly doing something that you
shouldn't be doing with fsck.
Currently, standardized file system-specific options are
somewhat in flux. 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 compati
bility only. This option is mapped to e2fsck's -p
option which is safe to use, unlike the -a option
that most file system checkers support.
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 cur
rently 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 admin
istrator to override the standard location of the
/etc/fstab file. It is also use for developers who
are testing fsck.
SEE ALSO
fstab(5), mkfs(8), fsck.minix(8), fsck.ext2(8) or
e2fsck(8), fsck.xiafs(8).
E2fsprogs version 1.34 July 2003 FSCK(8)
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