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Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)fsck.8 8.4 (Berkeley) 5/9/95 .\" .Dd March 20, 2008 .Dt FSCK 8 .Os BSD 4 .Sh NAME .Nm fsck .Nd filesystem consistency check and interactive repair .Sh SYNOPSIS .Nm fsck .Fl p .Op Fl f .Op Fl m Ar mode .Nm fsck .Op Fl b Ar block# .Op Fl l Ar maxparallel .Op Fl q .Op Fl y .Op Fl n .Op Fl m Ar mode .Op Ar filesystem .Ar ... .Sh DESCRIPTION The first form of .Nm fsck preens a standard set of filesystems or the specified filesystems. It is normally used in the script .Pa /etc/rc during automatic reboot. Here .Nm fsck reads the filesystem descriptor table (using .Xr getfsent 3 ) to determine which filesystems to check. Only partitions that have ``rw,'' ``rq'' or ``ro'' as options, and that have non-zero pass number are checked. Filesystems with pass number 1 (normally just the root filesystem) are checked one at a time. When pass 1 completes, all remaining filesystems are checked, running one process per disk drive. The disk drive containing each filesystem is inferred from the shortest prefix of the device name that ends in one or more digits; the remaining characters are assumed to be the partition designator. In preening mode, filesystems that are marked clean are skipped. Filesystems are marked clean when they are unmounted, when they have been mounted read-only, or when .Nm fsck runs on them successfully. .Pp The kernel takes care that only a restricted class of innocuous filesystem inconsistencies can happen unless hardware or software failures intervene. These are limited to the following: .Bl -item -compact -offset indent .It Unreferenced inodes .It Link counts in inodes too large .It Missing blocks in the free map .It Blocks in the free map also in files .It Counts in the super-block wrong .El .Pp These are the only inconsistencies that .Nm fsck with the .Fl 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 filesystem on which the correction will take place, and the nature of the correction. After successfully correcting a filesystem, .Nm fsck will print the number of files on that filesystem, the number of used and free blocks, and the percentage of fragmentation. .Pp If sent a .Dv QUIT signal, .Nm fsck 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. .Pp Without the .Fl p option, .Nm fsck 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 which are not correctable under the .Fl 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 .Li yes or .Li no . If the operator does not have write permission on the filesystem .Nm fsck will default to a .Fl n action. .Pp .Nm Fsck has more consistency checks than its predecessors .Em check , dcheck , fcheck , and .Em icheck combined. .Pp The following flags are interpreted by .Nm fsck . .Bl -tag .It Fl b Use the block specified immediately after the flag as the super block for the filesystem. Block 32 is usually an alternate super block. .It Fl f Force fsck to check `clean' filesystems when preening. .It Fl l Limit the number of parallel checks to the number specified in the following argument. By default, the limit is the number of disks, running one process per disk. If a smaller limit is given, the disks are checked round-robin, one filesystem at a time. .It Fl m Use the mode specified in octal immediately after the flag as the permission bits to use when creating the .Pa 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. .It Fl p "Preen" mode, described above. .It Fl q Do a quick check to determine if the filesystem was unmounted cleanly. .It Fl y Assume a yes response to all questions asked by .Nm fsck ; this should be used with great caution as this is a free license to continue after essentially unlimited trouble has been encountered. .It Fl n Assume a no response to all questions asked by .Nm fsck except for .Ql CONTINUE? , which is assumed to be affirmative; do not open the filesystem for writing. .El .Pp If no filesystems are given to .Nm fsck then a default list of filesystems is read using .Xr getfsent 3 . .Pp .Bl -enum -offset indent -compact Inconsistencies checked are as follows: .It Blocks claimed by more than one inode or the free map. .It Blocks claimed by an inode outside the range of the filesystem. .It Incorrect link counts. .It Size checks: .Bl -item -offset indent -compact .It Directory size not a multiple of DIRBLKSIZ. .It Partially truncated file. .El .It Bad inode format. .It Blocks not accounted for anywhere. .It Directory checks: .Bl -item -offset indent -compact .It File pointing to unallocated inode. .It Inode number out of range. .It Dot or dot-dot not the first two entries of a directory or having the wrong inode number. .El .It Super Block checks: .Bl -item -offset indent -compact .It More blocks for inodes than there are in the filesystem. .It Bad free block map format. .It Total free block and/or free inode count incorrect. .El .El .Pp Orphaned files and directories (allocated but unreferenced) are, with the operator's concurrence, reconnected by placing them in the .Pa lost+found directory. The name assigned is the inode number. If the .Pa lost+found directory does not exist, it is created. If there is insufficient space its size is increased. .Pp Because of inconsistencies between the block device and the buffer cache, the raw device should always be used. .Sh DIAGNOSTICS The diagnostics produced by .Nm fsck are fully enumerated and explained in Appendix A of .Rs .%T "Fsck \- The UNIX File System Check Program" .Re .Sh SEE ALSO .Xr fs 5 , .Xr fsck_hfs 8 , .Xr fsck_msdos 8 , .Xr getfsent 3 , .Xr newfs 8 , .Xr reboot 8