icheck -- Command

i-node consistency check
icheck [-s] [-b N ...] [ -v ] filesystem ...

Each block in a file system must be either free (i.e., in the free list) or
allocated (i.e., associated with exactly one i-node).  icheck examines each
specified filesystem, printing block  numbers that are claimed by more than
one i-node, or claimed by both an i-node and the free list.  It also checks
for blocks that appear more than  once in the block list of an i-node or in
the free list.

The option -v (verbose) causes icheck  to print a summary of block usage in
the filesystem.  The option -s  causes icheck to  ignore the free  list, to
note which blocks are claimed by i-nodes, and to rebuild the free list with
the remainder.  A list of block  numbers may be submitted with the -b flag;
icheck prints  the data  structure associated with  each block as  the file
system is scanned.

The raw  device should be used,  and the filesystem should  be unmounted if
possible.  If this is not possible  (e.g., on the root file system) and the
-s option is  used, the system must be rebooted  immediately to expunge the
obsolete superblock.

The exit status bits for a bad return are as follows:

0x01 Miscellaneous error (e.g. out of space)
0x02 Too hard to fix without human intervention
0x04 Bad free block
0x08 Missing blocks
0x10 Duplicates in free list
0x20 Bad block in free list

See Also

clri,
commands,
dcheck,
fsck,
ncheck,
sync,
umount

Diagnostics

The message  ``dups in free''  indicates a block  is in the  free list more
than once.   ``bad freelist'' indicates  the presence of bad  blocks on the
free list.  A ``bad'' block is one that lies outside the bounds of the file
system.  A ``dup'' (duplicated) block  is one associated with the free list
and an i-node, or with more  than one i-node.  All the errors above must be
corrected before the file system is mounted.  ``bad ifree'' means allocated
i-nodes are on the free i-node list; this is inconsequential.

This command has largely been replaced by fsck.

© 2012 by Stephen A. Ness