4.3BSD - /usr/man/cat8/fsck.0

FSCK(8)                                                                FSCK(8)


NAME
       fsck - file system consistency check and interactive repair

SYNOPSIS
       /etc/fsck -p [ filesystem ...  ]
       /etc/fsck [ -b block# ] [ -y ] [ -n ] [ filesystem ] ...

DESCRIPTION
       The  first  form  of  fsck  preens a standard set of filesystems or the
       specified file systems.  It is normally used in the script /etc/rc dur‐
       ing  automatic reboot.  In this case fsck reads the table /etc/fstab to
       determine which file systems to check.  It uses the  information  there
       to  inspect groups of disks in parallel taking maximum advantage of i/o
       overlap to check the file systems as quickly  as  possible.   Normally,
       the  root  file system will be checked on pass 1, other ‘‘root’’ (‘‘a’’
       partition) file systems on pass 2, other small file systems on separate
       passes  (e.g.  the ‘‘d’’ file systems on pass 3 and the ‘‘e’’ file sys‐
       tems on pass 4), and finally the large user file systems  on  the  last
       pass, e.g. pass 5.  Only partitions in fstab that are mounted ‘‘rw’’ or
       ‘‘rq’’ and that have non-zero pass number are checked.

       The system takes care that only a restricted class of innocuous  incon‐
       sistencies  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 list

              Blocks in the free list also in files

              Counts in the super-block wrong

       These are the only inconsistencies that fsck 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 identi‐
       fying the file system on which the correction will take place, and  the
       nature of the correction.  After successfully correcting a file system,
       fsck 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 will finish the file system checks, then
       exit with an abnormal return status that causes the automatic reboot to
       fail.   This  is useful when you wish to finish the file system checks,
       but do not want the machine to come up multiuser.

       Without the -p option, fsck audits and interactively repairs  inconsis‐
       tent  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 correc‐
       tion is to wait for the operator to respond yes or no.  If the operator
       does not have write permission on the file system fsck 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.

       -b    Use the block specified immediately after the flag as  the  super
             block for the file system.  Block 32 is always an alternate super
             block.

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

       -n    Assume a no response to all questions asked by fsck; do not  open
             the file system for writing.

       If no filesystems are given to fsck then a default list of file systems
       is read from the file /etc/fstab.

       Inconsistencies checked are as follows:

       1.    Blocks claimed by more than one inode or the free list.
       2.    Blocks claimed by an inode or the free list outside the range  of
             the file system.
       3.    Incorrect link counts.
       4.    Size checks:
                   Directory size not of proper format.
       5.    Bad inode format.
       6.    Blocks not accounted for anywhere.
       7.    Directory checks:
                   File pointing to unallocated inode.
                   Inode number out of range.
       8.    Super Block checks:

                   More blocks for inodes than there are in the file system.
       9.    Bad free block list format.
       10.   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 insuf‐
       ficient space its size is increased.

       Checking the raw device is almost always faster.

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

DIAGNOSTICS
       The  diagnostics produced by fsck are fully enumerated and explained in
       Appendix A of ‘‘Fsck - The UNIX File System Check Program’’ (SMM:5).

SEE ALSO
       fstab(5), fs(5), newfs(8), mkfs(8), crash(8V), reboot(8)

BUGS
       There should be some way to start a fsck -p at pass n.


4th Berkeley Distribution        May 21, 1986                          FSCK(8)