4.3BSD-Tahoe/usr/man/cat8/fsck.0
FSCK(8) UNIX Programmer's Manual FSCK(8)
NNAAMMEE
fsck - file system consistency check and interactive repair
SSYYNNOOPPSSIISS
//eettcc//ffsscckk --pp [ filesystem ... ]
//eettcc//ffsscckk [ --bb block# ] [ --cc ] [ --yy ] [ --nn ] [ filesystem ]
...
DDEESSCCRRIIPPTTIIOONN
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 //eettcc//rrcc during automatic reboot. In this case _f_s_c_k
reads the table //eettcc//ffssttaabb 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 map
Blocks in the free map also in files
Counts in the super-block wrong
These are the only inconsistencies that _f_s_c_k with the --pp
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
Printed 7/9/88 May 5, 1988 1
FSCK(8) UNIX Programmer's Manual FSCK(8)
to finish the file system checks, but do not want the
machine to come up multiuser.
Without the --pp 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 --pp 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
yyeess or nnoo. If the operator does not have write permission
on the file system _f_s_c_k will default to a --nn 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.
--bb Use the block specified immediately after the flag as
the super block for the file system. Block 32 is usu-
ally an alternate super block.
--yy 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.
--nn Assume a no response to all questions asked by _f_s_c_k;
do not open the file system for writing.
--cc If the file system is in the old (static table) for-
mat, convert it to the new (dynamic table) format. If
the file system is in the new format, convert it to
the old format provided the old format can support the
filesystem configuration. In interactive mode, _f_s_c_k
will list the direction the conversion is 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 direction
of 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 con-
verted at once. The format of a file system can be
determined from the first line of output from
_d_u_m_p_f_s(8).
If no filesystems are given to _f_s_c_k then a default list of
file systems is read from the file //eettcc//ffssttaabb.
Printed 7/9/88 May 5, 1988 2
FSCK(8) UNIX Programmer's Manual FSCK(8)
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 of proper format.
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.
8. Super Block checks:
More blocks for inodes than there are in the
file system.
9. Bad free block map 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 lloosstt++ffoouunndd 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.
FFIILLEESS
/etc/fstab contains default list of file systems
to check.
DDIIAAGGNNOOSSTTIICCSS
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).
SSEEEE AALLSSOO
fstab(5), fs(5), fsdb(8), newfs(8), mkfs(8), crash(8V),
reboot(8)
BBUUGGSS
There should be some way to start a ffsscckk --pp at pass _n.
Printed 7/9/88 May 5, 1988 3