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FSCK(8)			    System Manager's Manual		       FSCK(8)

NAME
       fsck - check and	repair a Linux file system

SYNOPSIS
       fsck  [ -sACVRTNP ] [ -t	fstype ] [filesys ... ]	[--] [ fs-specific-op-
       tions ]

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 run filesystems on different	physi-
       cal 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 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 fs-
	      list.  They must have the	format opts=fs-option.	If an  options
	      specifier	is present, then only filesystems which	contain	fs-op-
	      tion 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  en-
	      try.  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  sys-
	      tems 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 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, al-
	      though 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	repar-
	      tition the root filesystem to be small and compact (which	is re-
	      ally 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 ar-
	      guments, 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 do-
	      ing  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 ex-
	      pect, don't bother reporting it as a bug.	  You're  almost  cer-
	      tainly 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	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 use for developers who are testing fsck.

SEE ALSO
       fstab(5), mkfs(8), fsck.minix(8), fsck.ext2(8) or  e2fsck(8),  fsck.xi-
       afs(8).

E2fsprogs version 1.32		 November 2002			       FSCK(8)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | AUTHOR | FILES | ENVIRONMENT VARIABLES | SEE ALSO

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