4.3BSD-UWisc/man/cat8/fsck.8

FSCK(8)             UNIX Programmer's Manual              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 _f_s_c_k preens a standard set of filesystems
     or the specified file systems.  It is normally used in the
     script /etc/rc during automatic reboot.  In this case _f_s_c_k
     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 systems 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 inno-
     cuous 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 list

          Blocks in the free list also in files

          Counts in the super-block wrong

     These are the only inconsistencies that _f_s_c_k 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,
     _f_s_c_k will print the number of files on that file system, the
     number of used and free blocks, and the percentage of frag-
     mentation.

     If sent a QUIT signal, _f_s_c_k 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



Printed 12/27/86          May 21, 1986                          1






FSCK(8)             UNIX Programmer's Manual              FSCK(8)



     machine to come up multiuser.

     Without the -p option, _f_s_c_k 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 correct-
     able 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 con-
     sistency correction is to wait for the operator to respond
     yes or no.  If the operator does not have write permission
     on the file system _f_s_c_k will default to a -n action.

     _F_s_c_k has more consistency checks than its predecessors
     _c_h_e_c_k, _d_c_h_e_c_k, _f_c_h_e_c_k, and _i_c_h_e_c_k combined.

     The following flags are interpreted by _f_s_c_k.

     -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 _f_s_c_k;
           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 _f_s_c_k;
           do not open the file system for writing.

     If no filesystems are given to _f_s_c_k 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.



Printed 12/27/86          May 21, 1986                          2






FSCK(8)             UNIX Programmer's Manual              FSCK(8)



     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 _l_o_s_t+_f_o_u_n_d directory does not exist,
     it is created.  If there is insufficient 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 _f_s_c_k 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.





























Printed 12/27/86          May 21, 1986                          3