1ICHECK(1M)                                                          ICHECK(1M)
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NAME

6       icheck - file system storage consistency check
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SYNOPSIS

9       icheck [ -s ]  [ -b numbers ] [ filesystem ]
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DESCRIPTION

12       Icheck  examines  a  file  system, builds a bit map of used blocks, and
13       compares this bit map against the free list maintained on the file sys‐
14       tem.   If  the file system is not specified, a set of default file sys‐
15       tems is checked.  The normal output of icheck includes a report of
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17              The total number of files and the numbers of regular, directory,
18              block special and character special files.
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20              The  total  number  of blocks in use and the numbers of single-,
21              double-, and triple-indirect blocks and directory blocks.
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23              The number of free blocks.
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25              The number of blocks missing; i.e. not in any file  nor  in  the
26              free list.
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28       The  -s  option causes icheck to ignore the actual free list and recon‐
29       struct a new one by rewriting the super-block of the file system.   The
30       file  system  should  be  dismounted while this is done; if this is not
31       possible (for example if the root file system has to be salvaged)  care
32       should  be  taken  that the system is quiescent and that it is rebooted
33       immediately afterwards so that the old, bad in-core copy of the  super-
34       block  will not continue to be used.  Notice also that the words in the
35       super-block which indicate the size of the free list and of the  i-list
36       are  believed.   If  the  super-block has been curdled these words will
37       have to be patched.  The -s option causes the normal output reports  to
38       be suppressed.
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40       Following the -b option is a list of block numbers; whenever any of the
41       named blocks turns up in a file, a diagnostic is produced.
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43       Icheck is faster if the raw version of the special file is used,  since
44       it reads the i-list many blocks at a time.
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FILES

47       Default file systems vary with installation.
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SEE ALSO

50       dcheck(1), ncheck(1), filsys(5), clri(1)
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DIAGNOSTICS

53       For duplicate blocks and bad blocks (which lie outside the file system)
54       icheck announces the difficulty, the i-number, and the  kind  of  block
55       involved.   If a read error is encountered, the block number of the bad
56       block is printed and icheck considers it to contain 0.  `Bad freeblock'
57       means  that  a block number outside the available space was encountered
58       in the free list.  `n dups in free' means that n blocks were  found  in
59       the free list which duplicate blocks either in some file or in the ear‐
60       lier part of the free list.
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BUGS

63       Since icheck is inherently two-pass in nature,  extraneous  diagnostics
64       may be produced if applied to active file systems.
65       It  believes  even  preposterous  super-blocks and consequently can get
66       core images.
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