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FSCK
!!!FSCK
NAME
SYNOPSIS
DESCRIPTION
OPTIONS
AUTHOR
FILES
ENVIRONMENT VARIABLES
SEE ALSO
----
!!NAME


fsck - check and repair a Linux file system
!!SYNOPSIS


__fsck__ [[ __-sACVRTNP__ ] [[ __-t__ ''fstype'' ]
''filesys [[ ... ]'' [[--] [[ __fsck-options__
]
!!DESCRIPTION


__fsck__ is used to check and optionally repair a 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).
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.


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
128 - Shared library error
The exit code returned when all file systems are checked
using the __-A__ option 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 manual pages for further
details.
!!OPTIONS


__-s__


Serialize __fsck__ operations. This is a good idea if you
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'', and may be prefixed by a
negation operator. If an options specifier is present, then
only filesystems whose __/etc/fstab__ entry do (or do
not, if the options specifier was prefixed by a negation
operator) contain ''fs-option'' in their options field of
the __/etc/fstab__ file 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 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 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 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 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__


Display completion/progress bars for those filesystems
checkers (currently only for ext2) which support them. Fsck
will manage the filesystem checkers so that only one of them
will display a progress bar at a time.


__-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.


__fsck-options__


Options which which are not understood by __fsck__ are
passed to the filesystem-specific 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-specific 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 complicated, 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, __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 compatibility 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.


__-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.
!!AUTHOR


Theodore Ts'o (tytso@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 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).
----
14 pages link to fsck(8):
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Last edited on Tuesday, June 4, 2002 12:31:12 am by "perry"
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