1ICHECK(1M) ICHECK(1M)
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6 icheck - file system storage consistency check
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9 icheck [ -s ] [ -b numbers ] [ filesystem ]
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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
16 The total number of files and the numbers of regular, directory,
18 block special and character special files.
19 The total number of blocks in use and the numbers of single-,
21 double-, and triple-indirect blocks and directory blocks.
22 The number of free blocks.
24 The number of blocks missing; i.e. not in any file nor in the
26 free list.
27 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.
39 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.
42 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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47 Default file systems vary with installation.
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50 dcheck(1), ncheck(1), filsys(5), clri(1)
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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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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.
67 ICHECK(1M)