icheck - file system storage consistency check
icheck [ -s ] [ -b numbers ] [ filesystem ]
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
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 directory 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 sal-
vaged) 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.
filsys(5), clri(8), dcheck(8), fsck(8), ncheck(8)
For duplicate blocks and bad blocks (which lie outside the 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 encountered 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.
Since icheck is inherently two-pass in nature, extraneous diagnostics may be produced if
applied to active file systems. Since default file systems vary with installations,
icheck should use fstab(5).
It believes even preposterous super-blocks and consequently can get core images.
3rd Berkeley Distribution ICHECK(8)