ICHECK(8) ICHECK(8) NAME icheck, dcheck, ncheck - file system consistency check SYNOPSIS /etc/icheck [ -B ] [ -s ] [ -b numbers ] [ filesystem ] /etc/dcheck [ -B ] [ -i numbers ] [ filesystem ] /etc/ncheck [ -B ] [ -i numbers ] [ -a ] [ -s ] [ filesystem ] DESCRIPTION These programs perform consistency checks on file systems. For normal file system maintenance, see fsck(8). 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. 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. 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 or the free list, a diagnostic is produced. Dcheck reads the directories in a file system and compares the link-count in each i-node with the number of directory ICHECK(8) ICHECK(8) entries by which it is referenced. The -i flag is followed by a list of i-numbers; when one of those i-numbers turns up in a directory, the number, the i-number of the directory, and the name of the entry are reported. Ncheck generates a pathname vs. i-number list of all files in a file system. Names of directory files are followed by `/.'. The -i option reduces the report to only those files whose i-numbers follow. The -a option allows printing of the names `.' and `..', which are ordinarily suppressed. The -s option reduces the report to special files and files with set-user-ID mode; it is intended to discover concealed violations of security policy. The report is in no useful order, and probably should be sorted. These programs are faster if the raw version of the special file is used, since they read the i-list many blocks at a time. If filesystem is a special file, the minor device number is checked to distinguish between regular and bitmapped file systems. If the filesystem resides in a regular file, it is assumed to be a regular file system unless the -B option is used. FILES Default file systems vary with installation. SEE ALSO fsck(8), filsys(5), clri(8) DIAGNOSTICS 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 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. When a file turns up for which the link-count and the number of directory entries disagree, dcheck reports the relevant facts. Allocated files which have 0 link-count and no entries are also listed. The only dangerous situation occurs when there are more entries than links; if entries are removed, so the link-count drops to 0, the remaining entries point to thin air. They should be removed. When there are more links than entries, or there is an allocated file with neither links nor entries, some disk space may be lost but the situation will not degenerate. ICHECK(8) ICHECK(8) When the filesystem structure is improper, ncheck prints `??' to denote the `parent' of a parentless file. A path- name beginning with `...' denotes a loop. BUGS Since these commands are inherently two-pass in nature, extraneous diagnostics may be produced if applied to active file systems. They believe even preposterous super-blocks and consequently can get core images.