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NAME    [Toc]    [Back]

       fsck - check and repair a Linux file system

SYNOPSIS    [Toc]    [Back]

       fsck [ -sACVRTNP ] [ -t fstype ] filesys [ ... ] [--] [ fsck-options ]

DESCRIPTION    [Toc]    [Back]

       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

       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

OPTIONS    [Toc]    [Back]

       -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

       -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.

	      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

	      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 filesystemspecific
 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    [Toc]    [Back]

       Theodore Ts'o (tytso@mit.edu)

FILES    [Toc]    [Back]



       The  fsck  program's  behavior is affected by the following environment

       FSCK_FORCE_ALL_PARALLEL    [Toc]    [Back]
	      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    [Toc]    [Back]
	      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    [Toc]    [Back]
	      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    [Toc]    [Back]

       fstab(5),   mkfs(8),   fsck.minix(8),   fsck.ext2(8)   or    e2fsck(8),

E2fsprogs version 1.27		  March 2002			       FSCK(8)
[ Back ]
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