MirBSD manpage: fsck_ffs(8)

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


     fsck_ffs - Fast Filesystem consistency check and interactive repair


     fsck_ffs [-fnpy] [-b block#] [-c level] [-m mode] filesystem ...


     fsck_ffs performs interactive filesystem consistency checks and repairs
     for each filesystem specified. It is normally invoked from fsck(8).

     The kernel takes care that only a restricted class of innocuous filesys-
     tem inconsistencies can happen unless hardware or software failures in-
     tervene. These are limited to the following:

           Unreferenced inodes
           Link counts in inodes too large
           Missing blocks in the free map
           Blocks in the free map also in files
           Counts in the super-block wrong

     These are the only inconsistencies that fsck_ffs with the -p option will
     correct; if it encounters other inconsistencies, it exits with an abnor-
     mal return status and an automatic reboot will then fail. For each
     corrected inconsistency, one or more lines will be printed identifying
     the filesystem on which the correction will take place along with the na-
     ture of the correction. After successfully correcting a filesystem,
     fsck_ffs 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_ffs will finish the filesystem checks, then
     exit with an abnormal return status that causes an automatic reboot to
     fail. This is useful when you want to finish the filesystem checks during
     an automatic reboot, but do not want the machine to come up multiuser
     after the checks complete.

     If sent an INFO signal, fsck_ffs will print a line to standard error in-
     dicating the name of the device currently being checked, the current
     phase number, and phase-specific progress information.

     Without the -p option, fsck_ffs audits and interactively repairs incon-
     sistent conditions for filesystems. If the filesystem is inconsistent,
     the operator is prompted for concurrence before each correction is at-
     tempted. It should be noted that some of the corrective actions which are
     not correctable under the -p option 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_ffs will default to a -n action.

     fsck has more consistency checks than its predecessors check, dcheck,
     fcheck, and icheck combined.

     The following flags are interpreted by fsck_ffs:

     -b block#
             Use the block# specified as the super block for the filesystem.
             Block 32 is usually an alternate super block.

     -c level
             Convert the filesystem to the specified level. Note that the lev-
             el of a filesystem can only be raised. There are currently four
             levels defined:

             0       The filesystem is in the old (static table) format.

             1       The filesystem is in the new (dynamic table) format.

             2       The filesystem supports 32-bit UIDs and GIDs, short sym-
                     bolic links are stored in the inode, and directories have
                     an added field showing the file type.

             3       If maxcontig is greater than one, build the free segment
                     maps to aid in finding contiguous sets of blocks. If
                     maxcontig is equal to one, delete any existing segment

     -f      Force checking of filesystems. Normally, if a filesystem is
             cleanly unmounted, the kernel will set a "clean flag" in the
             filesystem superblock and fsck_ffs will not check the filesystem.
             This option forces fsck_ffs to check the filesystem, regardless
             of the state of the clean flag.

     -m mode
             Use the mode specified in octal as the permission bits to use
             when creating the lost+found directory rather than the default
             1700. In particular, systems that wish to have lost files acces-
             sible by all users on the system should use a less restrictive
             set of permissions such as 755.

     -n      Assume a "no" response to all questions asked by fsck_ffs except
             for "CONTINUE?", which is assumed to be affirmative. Filesystems
             will not be opened for writing. This is the default for filesys-
             tems to be checked that are concurrently mounted writable.

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

     In interactive mode, fsck_ffs will list the conversion to be made and ask
     whether the conversion should be done. If a negative answer is given, no
     further operations are done on the filesystem. In preen mode, the conver-
     sion is listed and done if possible without user interaction. Conversion
     in preen mode is best used when all the filesystems are being converted
     at once. The format of a filesystem can be determined from the first line
     of output from dumpfs(8).

     If no filesystems are given to fsck_ffs then a default list of filesys-
     tems is read from the file /etc/fstab.

     Inconsistencies checked are as follows:

     1.   Blocks claimed more than once by inodes or the free map.
     2.   Blocks claimed by an inode outside the range of the filesystem.
     3.   Incorrect link counts.
     4.   Size checks:
                Directory size not a multiple of DIRBLKSIZ.
                Partially truncated file.
     5.   Bad inode format.
     6.   Blocks not accounted for anywhere.
     7.   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.
     8.   Super Block checks:
                More blocks for inodes than there are in the filesystem.
                Bad free block map format.
                Total free block and/or free inode count incorrect.

     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.


     The diagnostics produced by fsck_ffs are fully enumerated and explained
     in Appendix A of fsck_ffs - The UNIX(R) Filesystem Check Program.


     fs(5), fstab(5), fsck(8), fsdb(8), growfs(8), mount_ffs(8), newfs(8),

     Marshall Kirk McKusick, fsck_ffs - The UNIX(R) Filesystem Check Program,

MirBSD #10-current            November 29, 1994                              2

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