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-options ]

DESCRIPTION

       fsck  is  used to check and optionally repair 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).
       Normally,  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.

       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-spe-
       cific checker is searched for in /sbin first, then in /etc/fs and /etc, and finally in the directories listed in the PATH environment vari-
       able.  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 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-sepa-
	      rated  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 speci-
	      fier is present, then only filesystems which contain 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 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 sys-
	      tem 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, 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.

       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 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  some-
	      thing 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  con-
	      figurations  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).

E2fsprogs version 1.32						   November 2002							   FSCK(8)