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FSCK_FFS(8)		  BSD System Manager's Manual		   FSCK_FFS(8)

     fsck_ffs, fsck_ufs	-- file	system consistency check and interactive re-

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

     The specified disk	partitions and/or file systems are checked.  In
     "preen" 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 in-
     tervene.  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	at-
     tempted.  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:

     -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

     -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 er-
	     rors are found, the file system is	marked as needing a foreground
	     check and fsck_ffs	exits without attempting any further cleaning.

     -b	     Use the block specified immediately after the flag	as the super
	     block for the file	system.	 Block 32 is usually an	alternate su-
	     per block.

     -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 an-
	     swer is given, no further operations are done on the file system.
	     In	preen mode, the	conversion is listed and done if possible
	     without user interaction.	Conversion in preen mode is best used
	     when all the file systems are being converted at once.  The for-
	     mat of a file system can be determined from the first line	of
	     output from dumpfs(8).

     -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).

     -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-

     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 di-
     rectory.  The name	assigned is the	inode number.  If the lost+found di-
     rectory does not exist, it	is created.  If	there is insufficient space
     its size is increased.

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

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

     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)

BSD				April 24, 2001				   BSD


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