415 lines
11 KiB
Groff
415 lines
11 KiB
Groff
.\" -*- nroff -*-
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.\" Copyright 1993, 1994, 1995 by Theodore Ts'o. All Rights Reserved.
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.\" This file may be copied under the terms of the GNU Public License.
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.\"
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.TH FSCK 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
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.SH NAME
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fsck \- check and repair a Linux file system
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.SH SYNOPSIS
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.B fsck
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[
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.B \-sAVRTMNP
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]
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[
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.B \-C
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[
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.I fd
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]
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]
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[
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.B \-t
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.I fstype
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]
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.I [filesys ... ]
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[\-\-] [
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.B fs-specific-options
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]
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.SH DESCRIPTION
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.B fsck
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is used to check and optionally repair one or more Linux file systems.
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.I filesys
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can be a device name (e.g.
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.IR /dev/hdc1 ", " /dev/sdb2 ),
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a mount point (e.g.
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.IR / ", " /usr ", " /home ),
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or an ext2 label or UUID specifier (e.g.
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UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd or LABEL=root).
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Normally, the
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.B fsck
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program will try to handle file systems on different physical disk drives
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in parallel to reduce the total amount of time needed to check all of the
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file systems.
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.PP
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If no file systems are specified on the command line, and the
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.B \-A
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option is not specified,
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.B fsck
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will default to checking file systems in
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.B /etc/fstab
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serially. This is equivalent to the
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.B \-As
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options.
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.PP
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The exit code returned by
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.B fsck
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is the sum of the following conditions:
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.br
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\ 0\ \-\ No errors
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.br
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\ 1\ \-\ File system errors corrected
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.br
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\ 2\ \-\ System should be rebooted
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.br
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\ 4\ \-\ File system errors left uncorrected
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.br
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\ 8\ \-\ Operational error
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.br
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\ 16\ \-\ Usage or syntax error
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.br
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\ 32\ \-\ Fsck canceled by user request
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.br
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\ 128\ \-\ Shared library error
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.br
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The exit code returned when multiple file systems are checked
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is the bit-wise OR of the exit codes for each
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file system that is checked.
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.PP
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In actuality,
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.B fsck
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is simply a front-end for the various file system checkers
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(\fBfsck\fR.\fIfstype\fR) available under Linux. The file
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system-specific checker is searched for in
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.I /sbin
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first, then in
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.I /etc/fs
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and
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.IR /etc ,
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and finally in the directories listed in the PATH environment
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variable. Please see the file system-specific checker manual pages for
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further details.
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.SH OPTIONS
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.TP
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.B \-s
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Serialize
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.B fsck
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operations. This is a good idea if you are checking multiple
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file systems and the checkers are in an interactive mode. (Note:
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.BR e2fsck (8)
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runs in an interactive mode by default. To make
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.BR e2fsck (8)
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run in a non-interactive mode, you must either specify the
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.B \-p
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or
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.B \-a
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option, if you wish for errors to be corrected automatically, or the
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.B \-n
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option if you do not.)
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.TP
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.BI \-t " fslist"
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Specifies the type(s) of file system to be checked. When the
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.B \-A
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flag is specified, only file systems that match
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.I fslist
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are checked. The
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.I fslist
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parameter is a comma-separated list of file systems and options
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specifiers. All of the file systems in this comma-separated list may be
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prefixed by a negation operator
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.RB ' no '
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or
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.RB ' ! ',
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which requests that only those file systems not listed in
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.I fslist
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will be checked. If all of the file systems in
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.I fslist
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are not prefixed by a negation operator, then only those file systems
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listed
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in
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.I fslist
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will be checked.
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.sp
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Options specifiers may be included in the comma-separated
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.IR fslist .
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They must have the format
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.BI opts= fs-option\fR.
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If an options specifier is present, then only file systems which contain
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.I fs-option
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in their mount options field of
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.B /etc/fstab
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will be checked. If the options specifier is prefixed by a negation
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operator, then only
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those file systems that do not have
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.I fs-option
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in their mount options field of
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.B /etc/fstab
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will be checked.
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.sp
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For example, if
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.B opts=ro
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appears in
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.IR fslist ,
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then only file systems listed in
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.B /etc/fstab
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with the
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.B ro
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option will be checked.
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.sp
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For compatibility with Mandrake distributions whose boot scripts
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depend upon an unauthorized UI change to the
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.B fsck
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program, if a file system type of
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.B loop
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is found in
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.IR fslist ,
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it is treated as if
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.B opts=loop
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were specified as an argument to the
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.B \-t
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option.
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.sp
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Normally, the file system type is deduced by searching for
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.I filesys
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in the
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.I /etc/fstab
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file and using the corresponding entry.
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If the type can not be deduced, and there is only a single file system
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given as an argument to the
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.B \-t
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option,
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.B fsck
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will use the specified file system type. If this type is not
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available, then the default file system type (currently ext2) is used.
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.TP
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.B \-A
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Walk through the
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.I /etc/fstab
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file and try to check all file systems in one run. This option is
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typically used from the
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.I /etc/rc
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system initialization file, instead of multiple commands for checking
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a single file system.
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.sp
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The root file system will be checked first unless the
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.B \-P
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option is specified (see below). After that,
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file systems will be checked in the order specified by the
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.I fs_passno
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(the sixth) field in the
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.I /etc/fstab
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file.
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File Systems with a
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.I fs_passno
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value of 0 are skipped and are not checked at all. File Systems with a
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.I fs_passno
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value of greater than zero will be checked in order,
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with file systems with the lowest
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.I fs_passno
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number being checked first.
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If there are multiple file systems with the same pass number,
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fsck will attempt to check them in parallel, although it will avoid running
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multiple file system checks on the same physical disk.
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.sp
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Hence, a very common configuration in
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.I /etc/fstab
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files is to set the root file system to have a
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.I fs_passno
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value of 1
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and to set all other file systems to have a
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.I fs_passno
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value of 2. This will allow
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.B fsck
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to automatically run file system checkers in parallel if it is advantageous
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to do so. System administrators might choose
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not to use this configuration if they need to avoid multiple file system
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checks running in parallel for some reason --- for example, if the
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machine in question is short on memory so that
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excessive paging is a concern.
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.TP
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.B \-C\fR [ \fI "fd" \fR ]
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Display completion/progress bars for those file system checkers (currently
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only for ext2 and ext3) which support them. Fsck will manage the
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file system checkers so that only one of them will display
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a progress bar at a time. GUI front-ends may specify a file descriptor
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.IR fd ,
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in which case the progress bar information will be sent to that file descriptor.
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.TP
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.B \-M
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Do not check mounted file systems and return an exit code of 0
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for mounted file systems.
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.TP
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.B \-N
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Don't execute, just show what would be done.
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.TP
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.B \-P
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When the
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.B \-A
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flag is set, check the root file system in parallel with the other file systems.
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This is not the safest thing in the world to do,
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since if the root file system is in doubt things like the
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.BR e2fsck (8)
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executable might be corrupted! This option is mainly provided
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for those sysadmins who don't want to repartition the root
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file system to be small and compact (which is really the right solution).
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.TP
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.B \-R
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When checking all file systems with the
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.B \-A
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flag, skip the root file system (in case it's already mounted read-write).
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.TP
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.B \-T
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Don't show the title on startup.
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.TP
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.B \-V
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Produce verbose output, including all file system-specific commands
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that are executed.
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.TP
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.B fs-specific-options
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Options which are not understood by
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.B fsck
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are passed to the file system-specific checker. These arguments
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.B must
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not take arguments, as there is no
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way for
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.B fsck
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to be able to properly guess which arguments take options and which
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don't.
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.IP
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Options and arguments which follow the
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.B \-\-
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are treated as file system-specific options to be passed to the
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file system-specific checker.
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.IP
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Please note that fsck is not
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designed to pass arbitrarily complicated options to file system-specific
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checkers. If you're doing something complicated, please just
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execute the file system-specific checker directly. If you pass
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.B fsck
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some horribly complicated option and arguments, and it doesn't do
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what you expect,
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.B don't bother reporting it as a bug.
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You're almost certainly doing something that you shouldn't be doing
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with
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.BR fsck.
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.PP
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Options to different file system-specific fsck's are not standardized.
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If in doubt, please consult the man pages of the file system-specific
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checker. Although not guaranteed, the following options are supported
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by most file system checkers:
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.TP
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.B \-a
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Automatically repair the file system without any questions (use
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this option with caution). Note that
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.BR e2fsck (8)
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supports
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.B \-a
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for backwards compatibility only. This option is mapped to
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.BR e2fsck 's
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.B \-p
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option which is safe to use, unlike the
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.B \-a
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option that some file system checkers support.
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.TP
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.B \-n
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For some file system-specific checkers, the
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.B \-n
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option will cause the fs-specific fsck to avoid attempting to repair any
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problems, but simply report such problems to stdout. This is however
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not true for all file system-specific checkers. In particular,
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.BR fsck.reiserfs (8)
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will not report any corruption if given this option.
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.BR fsck.minix (8)
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does not support the
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.B \-n
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option at all.
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.TP
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.B \-r
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Interactively repair the file system (ask for confirmations). Note: It
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is generally a bad idea to use this option if multiple fsck's are being
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run in parallel. Also note that this is
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.BR e2fsck 's
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default behavior; it supports this option for backwards compatibility
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reasons only.
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.TP
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.B \-y
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For some file system-specific checkers, the
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.B \-y
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option will cause the fs-specific fsck to always attempt to fix any
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detected file system corruption automatically. Sometimes an expert may
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be able to do better driving the fsck manually. Note that
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.B not
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all file system-specific checkers implement this option. In particular
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.BR fsck.minix (8)
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and
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.BR fsck.cramfs (8)
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does not support the
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.B -y
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option as of this writing.
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.SH AUTHOR
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Theodore Ts'o (tytso@mit.edu)
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.SH FILES
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.IR /etc/fstab .
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.SH ENVIRONMENT VARIABLES
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The
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.B fsck
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program's behavior is affected by the following environment variables:
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.TP
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.B FSCK_FORCE_ALL_PARALLEL
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If this environment variable is set,
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.B fsck
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will attempt to run all of the specified file systems in parallel,
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regardless of whether the file systems appear to be on the same
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device. (This is useful for RAID systems or high-end storage systems
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such as those sold by companies such as IBM or EMC.)
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.TP
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.B FSCK_MAX_INST
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This environment variable will limit the maximum number of file system
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checkers that can be running at one time. This allows configurations
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which have a large number of disks to avoid
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.B fsck
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starting too many file system checkers at once, which might overload
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CPU and memory resources available on the system. If this value is
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zero, then an unlimited number of processes can be spawned. This is
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currently the default, but future versions of
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.B fsck
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may attempt to automatically determine how many file system checks can
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be run based on gathering accounting data from the operating system.
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.TP
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.B PATH
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The
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.B PATH
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environment variable is used to find file system checkers. A set of
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system directories are searched first:
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.BR /sbin ,
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.BR /sbin/fs.d ,
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.BR /sbin/fs ,
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.BR /etc/fs ,
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and
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.BR /etc .
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Then the set of directories found in the
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.B PATH
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environment are searched.
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.TP
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.B FSTAB_FILE
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This environment variable allows the system administrator
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to override the standard location of the
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.B /etc/fstab
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file. It is also useful for developers who are testing
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.BR fsck .
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.SH SEE ALSO
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.BR fstab (5),
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.BR mkfs (8),
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.BR fsck.ext2 (8)
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or
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.BR fsck.ext3 (8)
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or
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.BR e2fsck (8),
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.BR cramfsck (8),
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.BR fsck.minix (8),
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.BR fsck.msdos (8),
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.BR fsck.jfs (8),
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.BR fsck.nfs (8),
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.BR fsck.vfat (8),
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.BR fsck.xfs (8),
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.BR fsck.xiafs (8),
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.BR reiserfsck (8).
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