Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
FSCK_FFS(8)		FreeBSD	System Manager's Manual		   FSCK_FFS(8)

     fsck_ffs, fsck_ufs	-- file	system consistency check and interactive

     fsck_ffs [-BCdEFfnpRrSyZ] [-b block] [-c level] [-m mode] filesystem ...

     The specified disk	partitions and/or file systems are checked.  In
     "preen" or	"check clean" mode the clean flag of each file system's
     superblock	is examined and	only those file	systems	that are not marked
     clean are checked.	 File systems are marked clean when they are
     unmounted,	when they have been mounted read-only, or when fsck_ffs	runs
     on	them successfully.  If the -f option is	specified, the file systems
     will be checked regardless	of the state of	their clean flag.

     The kernel	takes care that	only a restricted class	of innocuous file sys-
     tem inconsistencies can happen unless hardware or software	failures
     intervene.	 These are limited to the following:

	   Unreferenced	inodes
	   Link	counts in inodes too large
	   Missing blocks in the free map
	   Blocks in the free map also in files
	   Counts in the super-block wrong

     These are the only	inconsistencies	that fsck_ffs with the -p option will
     correct; if it encounters other inconsistencies, it exits with an abnor-
     mal return	status and an automatic	reboot will then fail.	For each cor-
     rected inconsistency one or more lines will be printed identifying	the
     file system on which the correction will take place, and the nature of
     the correction.  After successfully correcting a file system, fsck_ffs
     will print	the number of files on that file system, the number of used
     and free blocks, and the percentage of fragmentation.

     If	sent a QUIT signal, fsck_ffs will finish the file system checks, then
     exit with an abnormal return status that causes an	automatic reboot to
     fail.  This is useful when	you want to finish the file system checks dur-
     ing an automatic reboot, but do not want the machine to come up multiuser
     after the checks complete.

     If	fsck_ffs receives a SIGINFO (see the ``status''	argument for stty(1))
     signal, a line will be written to the standard output indicating the name
     of	the device currently being checked, the	current	phase number and
     phase-specific progress information.

     Without the -p option, fsck_ffs audits and	interactively repairs incon-
     sistent conditions	for file systems.  If the file system is inconsistent
     the operator is prompted for concurrence before each correction is
     attempted.	 It should be noted that some of the corrective	actions	which
     are not correctable under the -p option will result in some loss of data.
     The amount	and severity of	data lost may be determined from the diagnos-
     tic output.  The default action for each consistency correction is	to
     wait for the operator to respond yes or no.  If the operator does not
     have write	permission on the file system fsck_ffs will default to a -n

     The following flags are interpreted by fsck_ffs:

     -B	     A check is	done on	the specified and possibly active file system.
	     The set of	corrections that can be	done is	limited	to those done
	     when running in preen mode	(see the -p flag).  If unexpected
	     errors are	found, the file	system is marked as needing a fore-
	     ground check and fsck_ffs exits without attempting	any further

     -b	     Use the block specified immediately after the flag	as the super
	     block for the file	system.	 An alternate super block is usually
	     located at	block 32 for UFS1, and block 160 for UFS2.

	     See the -N	flag of	newfs(8).

     -C	     Check if file system was dismounted cleanly.  If so, skip file
	     system checks (like "preen").  However, if	the file system	was
	     not cleanly dismounted, do	full checks, as	if fsck_ffs was
	     invoked without -C.

     -c	     Convert the file system to	the specified level.  Note that	the
	     level of a	file system can	only be	raised.	 There are currently
	     four levels defined:

	     0	     The file system is	in the old (static table) format.

	     1	     The file system is	in the new (dynamic table) format.

	     2	     The file system supports 32-bit uid's and gid's, short
		     symbolic links are	stored in the inode, and directories
		     have an added field showing the file type.

	     3	     If	maxcontig is greater than one, build the free segment
		     maps to aid in finding contiguous sets of blocks.	If
		     maxcontig is equal	to one,	delete any existing segment

	     In	interactive mode, fsck_ffs will	list the conversion to be made
	     and ask whether the conversion should be done.  If	a negative
	     answer is given, no further operations are	done on	the file sys-
	     tem.  In preen mode, the conversion is listed and done if possi-
	     ble without user interaction.  Conversion in preen	mode is	best
	     used when all the file systems are	being converted	at once.  The
	     format of a file system can be determined from the	first line of
	     output from dumpfs(8).

	     This option implies the -f	flag.

     -d	     Enable debugging messages.

     -E	     Clear unallocated blocks, notifying the underlying	device that
	     they are not used and that	their contents may be discarded.  This
	     is	useful for filesystems which have been mounted on systems
	     without TRIM support, or with TRIM	support	disabled, as well as
	     filesystems which have been copied	from one device	to another.

	     See the -E	and -t flags of	newfs(8), and the -t flag of

     -F	     Determine whether the file	system needs to	be cleaned immediately
	     in	foreground, or if its cleaning can be deferred to background.
	     To	be eligible for	background cleaning it must have been running
	     with soft updates,	not have been marked as	needing	a foreground
	     check, and	be mounted and writable	when the background check is
	     to	be done.  If these conditions are met, then fsck_ffs exits
	     with a zero exit status.  Otherwise it exits with a non-zero exit
	     status.  If the file system is clean, it will exit	with a non-
	     zero exit status so that the clean	status of the file system can
	     be	verified and reported during the foreground checks.  Note that
	     when invoked with the -F flag, no cleanups	are done.  The only
	     thing that	fsck_ffs does is to determine whether a	foreground or
	     background	check is needed	and exit with an appropriate status

     -f	     Force fsck_ffs to check `clean' file systems when preening.

     -m	     Use the mode specified in octal immediately after the flag	as the
	     permission	bits to	use when creating the lost+found directory
	     rather than the default 1777.  In particular, systems that	do not
	     wish to have lost files accessible	by all users on	the system
	     should use	a more restrictive set of permissions such as 700.

     -n	     Assume a no response to all questions asked by fsck_ffs except
	     for `CONTINUE?', which is assumed to be affirmative; do not open
	     the file system for writing.

     -p	     Preen file	systems	(see above).

     -R	     Instruct fsck_ffs to restart itself if it encounters certain
	     errors that warrant another run.  It will limit itself to a maxi-
	     mum of 10 restarts	in a given run in order	to avoid an endless
	     loop with extremely corrupted filesystems.

     -r	     Free up excess unused inodes.  Decreasing the number of preallo-
	     cated inodes reduces the running time of future runs of fsck_ffs
	     and frees up space	that can allocated to files.  The -r option is
	     ignored when running in preen mode.

     -S	     Surrender on error.  With this flag enabled, a hard error
	     returned on disk i/o will cause fsck_ffs to abort instead of con-
	     tinuing on	and possibly tripping over more	i/o errors.

     -y	     Assume a yes response to all questions asked by fsck_ffs; this
	     should be used with great caution as this is a free license to
	     continue after essentially	unlimited trouble has been encoun-

     -Z	     Similar to	-E, but	overwrites unused blocks with zeroes.  If both
	     -E	and -Z are specified, blocks are first zeroed and then erased.

     Inconsistencies checked are as follows:

     1.	  Blocks claimed by more than one inode	or the free map.
     2.	  Blocks claimed by an inode outside the range of the file system.
     3.	  Incorrect link counts.
     4.	  Size checks:
		Directory size not a multiple of DIRBLKSIZ.
		Partially truncated file.
     5.	  Bad inode format.
     6.	  Blocks not accounted for anywhere.
     7.	  Directory checks:
		File pointing to unallocated inode.
		Inode number out of range.
		Directories with unallocated blocks (holes).
		Dot or dot-dot not the first two entries of a directory	or
		having the wrong inode number.
     8.	  Super	Block checks:
		More blocks for	inodes than there are in the file system.
		Bad free block map format.
		Total free block and/or	free inode count incorrect.

     Orphaned files and	directories (allocated but unreferenced) are, with the
     operator's	concurrence, reconnected by placing them in the	lost+found
     directory.	 The name assigned is the inode	number.	 If the	lost+found
     directory does not	exist, it is created.  If there	is insufficient	space
     its size is increased.

     The full foreground fsck_ffs checks for many more problems	that may occur
     after an unrecoverable disk write error.  Thus, it	is recommended that
     you perform foreground fsck_ffs on	your systems periodically and whenever
     you encounter unrecoverable disk write errors or file-system-related pan-

     /etc/fstab	 contains default list of file systems to check.

     The fsck_ffs utility exits	0 on success, and >0 if	an error occurs.

     If	the option -F is used, fsck_ffs	exits 7	if the file system is clean.

     The diagnostics produced by fsck_ffs are fully enumerated and explained
     in	Appendix A of Fsck - The UNIX File System Check	Program.

     fs(5), fstab(5), fsck(8), fsdb(8),	newfs(8), reboot(8)

     A fsck utility appeared in	4.0BSD.	 It became fsck_ffs in FreeBSD 5.0
     with the introduction of the filesystem independent wrapper as fsck.

FreeBSD	11.1		       February	14, 2017		  FreeBSD 11.1


Want to link to this manual page? Use this URL:

home | help