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FSCK_LFS(8)               BSD System Manager's Manual              FSCK_LFS(8)

NAME
     fsck_lfs -- Log-structured File System consistency check and interactive
     repair

SYNOPSIS
     fsck_lfs [-b block#] [-d] [-p] [-y] [-n] filesystem ...

DESCRIPTION
     fsck_lfs performs interactive filesystem consistency checks and repair
     for each of the filesystems specified on the command line.  It is nor-
     mally invoked from fsck(8).

     The design of LFS takes care that no filesystem inconsistencies can hap-
     pen unless hardware or software failures intervene.  fsck_lfs will report
     and optionally correct any such inconsistencies.

     For each corrected inconsistency one or more lines will be printed iden-
     tifying the filesystem on which the correction will take place, and the
     nature of the correction.  After successfully correcting a filesystem,
     fsck_lfs will print the number of files on that filesystem, the number of
     used and free blocks, and the percentage of fragmentation.

     If sent a QUIT signal, fsck_lfs will finish the filesystem checks, then
     exit with an abnormal return status.

     Without the -p option, fsck_lfs audits and interactively repairs incon-
     sistent conditions for filesystems.  If the filesystem is inconsistent
     the operator is prompted for concurrence before each correction is
     attempted.  It should be noted that some of the corrective actions will
     result in some loss of data.  The amount and severity of data lost may be
     determined from the diagnostic output.  The default action for each con-
     sistency correction is to wait for the operator to respond yes or no.  If
     the operator does not have write permission on the filesystem fsck_lfs
     will default to a -n action.

     The following flags are interpreted by fsck_lfs.

     -b      Use the block specified immediately after the flag as the super
             block for the filesystem.

     -d      Print debugging output.

     -n      Assume a no response to all questions asked by fsck_lfs except
             for 'CONTINUE?', which is assumed to be affirmative; do not open
             the filesystem for writing.

     -p      Specify ``preen'' mode.  Currently, in this mode fsck_lfs rolls
             forward from the older checkpoint, and performs no other action.

     -y      Assume a yes response to all questions asked by fsck_lfs; this
             should be used with great caution as this is a free license to
             continue after essentially unlimited trouble has been encoun-
             tered.

           Inconsistencies checked are as follows:
           1.   Blocks claimed by more than one inode.
           2.   Blocks claimed by an inode outside the range of the filesys-
                tem.
           3.   Incorrect link counts.
           4.   Size checks:
                      Directory size not a multiple of DIRBLKSIZ.
                      Partially truncated file.
           5.   Bad inode format.
           6.   Directory checks:
                      File pointing to unallocated inode.
                      Inode number out of range.
                      Dot or dot-dot not the first two entries of a directory
                      or having the wrong inode number.
           7.   Super Block checks:
                      More blocks for inodes than there are in the filesystem.
           8.   Index File checks:
                      ``In use'' inodes on free list, or free inodes not on
                      free list.
                      Segment block counts incorrect, or ``clean'' segments
                      containing live data.

     Orphaned files and directories (allocated but unreferenced) are, with the
     operator's concurrence, reconnected by placing them in the lost+found
     directory.  The name assigned is the inode number.  If the lost+found
     directory does not exist, it is created.  If there is insufficient space
     its size is increased.

     Because of inconsistencies between the block device and the buffer cache,
     the raw device should always be used.

DIAGNOSTICS
     The diagnostics produced by fsck_lfs are fully enumerated and explained
     in Appendix A of Fsck - The UNIX File System Check Program.

SEE ALSO
     fstab(5), fsck(8), newfs_lfs(8), reboot(8)

HISTORY
     The fsck_lfs program was first made available in NetBSD 1.4.

AUTHORS
     Most of the fsck_lfs program was taken from fsck_ffs(8); what was not was
     written by Konrad Schroder <perseantAThhhh.org>.

BSD                             March 28, 2003                             BSD