2.11BSD#431 - /usr/man/cat8/icheck.0

ICHECK(8)	    UNIX Programmer's Manual		ICHECK(8)


NAME
     icheck - file system storage consistency check

SYNOPSIS
     icheck [ -s ]  [ -b numbers ] [ filesystem ]

DESCRIPTION
     Icheck examines a file system, builds a bit map of used
     blocks, and compares this bit map against the free list
     maintained on the file system.  If the file system is not
     specified, a set of default file systems is checked.  The
     normal output of icheck includes a report of

	  The total number of files and the numbers of regular,
	  directory, block special and character special files,
	  quota nodes, and symbolic links.

	  The total number of blocks in use and the numbers of
	  single-, double-, and triple-indirect blocks and direc-
	  tory blocks.

	  The number of free blocks.

	  The number of blocks missing; i.e. not in any file nor
	  in the free list.

     The -s option causes icheck to ignore the actual free list
     and reconstruct a new one by rewriting the super-block of
     the file system.  The file system should be dismounted while
     this is done; if this is not possible (for example if the
     root file system has to be salvaged) care should be taken
     that the system is quiescent and that it is rebooted immedi-
     ately afterwards so that the old, bad in-core copy of the
     super-block will not continue to be used.	Notice also that
     the words in the super-block which indicate the size of the
     free list and of the i-list are believed.	If the super-
     block has been curdled these words will have to be patched.
     The -s option causes the normal output reports to be
     suppressed.

     Following the -b option is a list of block numbers; whenever
     any of the named blocks turns up in a file, a diagnostic is
     produced.

     Icheck is faster if the raw version of the special file is
     used, since it reads the i-list many blocks at a time.

SEE ALSO
     filsys(5), clri(8), dcheck(8), fsck(8), ncheck(8)

DIAGNOSTICS
     For duplicate blocks and bad blocks (which lie outside the


Printed 11/24/99						1


ICHECK(8)	    UNIX Programmer's Manual		ICHECK(8)


     file system) icheck announces the difficulty, the i-number,
     and the kind of block involved.  If a read error is encoun-
     tered, the block number of the bad block is printed and
     icheck considers it to contain 0.	`Bad freeblock' means
     that a block number outside the available space was encoun-
     tered in the free list.  `n dups in free' means that n
     blocks were found in the free list which duplicate blocks
     either in some file or in the earlier part of the free list.

BUGS
     Since icheck is inherently two-pass in nature, extraneous
     diagnostics may be produced if applied to active file sys-
     tems.  Since default file systems vary with installations,
     icheck should use fstab(5).
     It believes even preposterous super-blocks and consequently
     can get core images.


Printed 11/24/99						2