Man Linux: Main Page and Category List


     fsck.ffs, fsck.ufs - file system consistency check and interactive repair


     fsck.ffs [-BDFpfny] [-b block] [-c level] [-m mode] filesystem ...


     The specified disk partitions and/or file systems are checked.  In
     "preen" or "check clean" mode the clean flag of each file system’s
     superblock is examined and only those file systems that are not marked
     clean are checked.  File systems are marked clean when they are
     unmounted, when they have been mounted read-only, or when fsck.ffs runs
     on them successfully.  If the -f option is specified, the file systems
     will be checked regardless of the state of their clean flag.

     The kernel takes care that only a restricted class of innocuous file
     system inconsistencies can happen unless hardware or software failures
     intervene.  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
     abnormal return status and an automatic reboot will then fail.  For each
     corrected inconsistency one or more lines will be printed identifying the
     file system on which the correction will take place, and the nature of
     the correction.  After successfully correcting a file system, fsck.ffs
     will print the number of files on that file system, the number of used
     and free blocks, and the percentage of fragmentation.

     If sent a QUIT signal, fsck.ffs will finish the file system checks, then
     exit with an abnormal return status that causes an automatic reboot to
     fail.  This is useful when you want to finish the file system checks
     during an automatic reboot, but do not want the machine to come up
     multiuser after the checks complete.

     If fsck.ffs receives a SIGINFO (see the “status” argument for stty(1))
     signal, a line will be written to the standard output indicating 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
     inconsistent conditions for file systems.  If the file system is
     inconsistent the operator is prompted for concurrence before each
     correction is attempted.  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 file system fsck.ffs will
     default to a -n action.

     The following flags are interpreted by fsck.ffs:

     -F      Determine whether the file system needs to be cleaned immediately
             in foreground, or if its cleaning can be deferred to background.
             To be eligible for background cleaning it must have been running
             with soft updates, not have been marked as needing a foreground
             check, and be mounted and writable when the background check is
             to be done.  If these conditions are met, then fsck.ffs exits
             with a zero exit status.  Otherwise it exits with a non-zero exit
             status.  If the file system is clean, it will exit with a non-
             zero exit status so that the clean status of the file system can
             be verified and reported during the foreground checks.  Note that
             when invoked with the -F flag, no cleanups are done.  The only
             thing that fsck.ffs does is to determine whether a foreground or
             background check is needed and exit with an appropriate status

     -B      A check is done on the specified and possibly active file system.
             The set of corrections that can be done is limited to those done
             when running in preen mode (see the -p flag).  If unexpected
             errors are found, the file system is marked as needing a
             foreground check and fsck.ffs exits without attempting any
             further cleaning.

     -b      Use the block specified immediately after the flag as the super
             block for the file system.  An alternate super block is usually
             located at block 32 for UFS1, and block 160 for UFS2.

     -C      Check if file system was dismouted cleanly.  If so, skip file
             system checks (like "preen").  However, if the file system was
             not cleanly dismounted, do full checks, is if fsck.ffs was
             invoked without -C.

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

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

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

             2       The file system supports 32-bit uid’s and gid’s, short
                     symbolic 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

             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 file
             system.  In preen mode, the conversion is listed and done if
             possible without user interaction.  Conversion in preen mode is
             best used when all the file systems are being converted at once.
             The format of a file system can be determined from the first line
             of output from dumpfs(8).

     -D      Run fsck.ffs in ’damaged recovery’ mode, which will enable
             certain aggressive operations that can make fsck.ffs to survive
             with file systems that has very serious data damage, which is an
             useful last resort when on disk data damage is very serious and
             causes fsck.ffs to crash otherwise.  Be very careful using this
             flag, it is dangerous if there are data transmission hazards
             because a false positive cylinder group magic number mismatch
             could cause irrevertible data loss!

             This option implies the -f flag.

     -f      Force fsck.ffs to check ‘clean’ file systems when preening.

     -m      Use the mode specified in octal immediately after the flag as the
             permission bits to use when creating the lost+found directory
             rather than the default 1777.  In particular, systems that do not
             wish to have lost files accessible by all users on the system
             should use a more restrictive set of permissions such as 700.

     -n      Assume a no response to all questions asked by fsck.ffs except
             for ‘CONTINUE?’, which is assumed to be affirmative; do not open
             the file system for writing.

     -p      Preen file systems (see above).

     -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

     Inconsistencies checked are as follows:

     1.   Blocks claimed by more than one inode or the free map.
     2.   Blocks claimed by an inode outside the range of the file system.
     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.
                Directories with unallocated blocks (holes).
                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 file system.
                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.


     /etc/fstab  contains default list of file systems to check.


     The fsck.ffs utility exits 0 on success, and >0 if an error occurs.


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


     fs(5), fstab(5), fsck(8), fsdb(8), reboot(8)