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FSCK_EXT2FS(8)		  BSD System Manager's Manual		FSCK_EXT2FS(8)

     fsck_ext2fs -- ext2 File System consistency check and interactive repair

     fsck_ext2fs [-dfnpUy] [-b block#] [-c level] [-m mode] filesystem ...

     fsck_ext2fs performs interactive filesystem consistency checks and	repair
     for each of the filesystems specified on the command line.	 It is nor-
     mally invoked from	fsck(8).

     The kernel	takes care that	only a restricted class	of innocuous filesys-
     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_ext2fs in "preen" mode (with
     the -p option) will correct; if it	encounters other inconsistencies, it
     exits with	an abnormal return status.  For	each corrected inconsistency
     one or more lines will be printed identifying the filesystem on which the
     correction	will take place, and the nature	of the correction.  After suc-
     cessfully correcting a filesystem,	fsck_ext2fs will print the number of
     files on that filesystem and the number of	used and free blocks.

     If	sent a QUIT signal, fsck_ext2fs	will finish the	filesystem checks,
     then exit with an abnormal	return status.

     Without the -p option, fsck_ext2fs	audits and interactively repairs in-
     consistent	conditions for filesystems.  If	the filesystem 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 filesystem fsck_ext2fs will default to a -n

     The following flags are interpreted by fsck_ext2fs.

     -b	     Use the block specified immediately after the flag	as the super
	     block for the filesystem.	Block 8193 is usually an alternate su-
	     per block.

     -d	     Print debugging output.

     -f	     Force checking of file systems.  Normally,	if a file system is
	     cleanly unmounted,	the kernel will	set a "clean flag" in the file
	     system superblock,	and fsck_ext2fs	will not check the file	sys-
	     tem.  This	option forces fsck_ext2fs to check the file system,
	     regardless	of the state of	the clean flag.

     -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_ext2fs	except
	     for `CONTINUE?', which is assumed to be affirmative; do not open
	     the filesystem for	writing.

     -p	     Specify "preen" mode, described above.

     -U	     Resolve numeric userids to	usernames.

     -y	     Assume a yes response to all questions asked by fsck_ext2fs; 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 filesys-
	   3.	Incorrect link counts.
	   4.	Size checks:
		      Directory	size not a multiple of filesystem block	size.
		      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.
		      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 filesystem.
		      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.

     Because of	inconsistencies	between	the block device and the buffer	cache,
     the raw device should always be used.

     The diagnostics produced by fsck_ext2fs are fully enumerated and ex-
     plained in	Appendix A of Fsck - The UNIX File System Check	Program.

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

BSD				October	9, 2008				   BSD


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