| FSCK_LFS(8) | System Manager's Manual | FSCK_LFS(8) | 
fsck_lfs —
| fsck_lfs | [ -dfpqU] [-bblock] [-mmode] [-y|-n] filesystem
      ... | 
fsck_lfs performs interactive filesystem consistency
  checks and repair for each of the filesystems specified on the command line.
  It is normally invoked from
  fsck(8).
The design of LFS takes care that no filesystem inconsistencies
    can happen 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
    identifying 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
    inconsistent 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
    consistency 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
    block-d-ffsck_lfs will not check the
      file system. This option forces fsck_lfs to check
      the file system, regardless of the state of the clean flag.-m
    mode-nfsck_lfs except for
      ‘CONTINUE?’, which is assumed to be
      affirmative; do not open the filesystem for writing.-pfsck_lfs does nothing.-q-U-yfsck_lfs; this should be used with great caution
      as this is a free license to continue after essentially unlimited trouble
      has been encountered.Inconsistencies checked are as follows:
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.
fsck_lfs are fully
  enumerated and explained in Appendix A of
  Fsck - The UNIX File System Check
  Program.
fsck_lfs program was first made available in
  NetBSD 1.4.
fsck_lfs program was taken from
  fsck_ffs(8); what was not was
  written by Konrad Schroder
  <perseant@NetBSD.org>.
| July 12, 2014 | NetBSD 10.0 |