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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 sys-
       tems.   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).  Nor-
       mally, the fsck program 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	specified,  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 manual 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 inter-
	      active 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  con-
	      tain  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	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 sin-
	      gle  filesystem given as an argument to the -t option, fsck will
	      use the specified filesystem type.  If this type is  not	avail-
	      able,  then  the	default	 file  system type (currently ext2) is
	      used.

       -A     Walk through the /etc/fstab file and try to check all file  sys-
	      tems 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  mul-
	      tiple  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	 filesystem  checkers so that only one of them
	      will display a progress bar at a time.  GUI front-ends may spec-
	      ify  a file descriptor fd, in which case the progress bar infor-
	      mation 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	repar-
	      tition  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 com-
	      mands that are executed.

       fs-specific-options
	      Options 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 com-
	      plicated 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  com-
	      plicated	option	and  arguments,	 and  it  doesn't  do what you
	      expect, don'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-specific fsck to avoid attempting to repair any problems,
	      but simply report such problems to stdout.  This is however  not
	      true  for	 all  filesystem-specific  checkers.   In  particular,
	      fsck.reiserfs(8) will not report any corruption  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-specific fsck to  always  attempt	to  fix	 any  detected
	      filesystem corruption automatically.  Sometimes an expert may be
	      able to do better driving the fsck manually.  Note that not  all
	      filesystem-specific checkers implement this option.  In particu-
	      lar fsck.minix(8) and fsck.cramfs(8) does	 not  support  the  -y
	      option as of this writing.

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 check-
	      ers.  A set of system directories	 are  searched	first:	/sbin,
	      /sbin/fs.d, /sbin/fs, /etc/fs, and /etc.	Then the set of direc-
	      tories 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 fsck.ext3(8)	or  e2fsck(8),	cramf-
       sck(8),	 fsck.minix(8),	  fsck.msdos(8),   fsck.jfs(8),	  fsck.nfs(8),
       fsck.vfat(8), fsck.xfs(8), fsck.xiafs(8), reiserfsck(8).



E2fsprogs version 1.39		   May 2006			       FSCK(8)
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