fsck - file system consistency check and interactive repair
S
\bSY
\bYN
\bNO
\bOP
\bPS
\bSI
\bIS
\bS
f
\bfs
\bsc
\bck
\bk -
\b-p
\bp [ -
\b-m
\bm mode ]
f
\bfs
\bsc
\bck
\bk [ -
\b-b
\bb block# ] [ -
\b-c
\bc ] [ -
\b-y
\by ] [ -
\b-n
\bn ] [ -
\b-m
\bm mode ] [
D
\bDE
\bES
\bSC
\bCR
\bRI
\bIP
\bPT
\bTI
\bIO
\bON
\bN
The first form of _
\bf_
\bs_
\bc_
\bk preens a standard set of filesystems
or the specified file systems. It is normally used in the
script /
\b/e
\bet
\btc
\bc/
\b/r
\brc
\bc during automatic reboot. Here _
\bf_
\bs_
\bc_
\bk reads the
table /
\b/e
\bet
\btc
\bc/
\b/f
\bfs
\bst
\bta
\bab
\bb to determine which file systems to check.
Only partitions in fstab that are mounted ``rw,'' ``rq'' or
``ro'' 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 com-
pletes, all remaining filesystems are checked, running one
process per disk drive. The disk drive containing each
filesystem is inferred from the longest prefix of the device
name that ends in a digit; the remaining characters are
assumed to be the partition designator.
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:
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 _
\bf_
\bs_
\bc_
\bk with the -
\b-p
\bp
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,
_
\bf_
\bs_
\bc_
\bk will print the number of files on that file system, the
number of used and free blocks, and the percentage of frag-
If sent a QUIT signal, _
\bf_
\bs_
\bc_
\bk will finish the file system
checks, then exit with an abnormal return status that causes
an automatic reboot to fail. This is useful when to finish
the file system checks during an automatic reboot, but do
Printed 7/27/90 February 1
not want the machine to come up multiuser after the checks
Without the -
\b-p
\bp option, _
\bf_
\bs_
\bc_
\bk 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 -
\b-p
\bp 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
y
\bye
\bes
\bs or n
\bno
\bo. If the operator does not have write permission
on the file system _
\bf_
\bs_
\bc_
\bk will default to a -
\b-n
\bn action.
_
\bF_
\bs_
\bc_
\bk has more consistency checks than its predecessors
_
\bc_
\bh_
\be_
\bc_
\bk, _
\bd_
\bc_
\bh_
\be_
\bc_
\bk, _
\bf_
\bc_
\bh_
\be_
\bc_
\bk, and _
\bi_
\bc_
\bh_
\be_
\bc_
\bk combined.
The following flags are interpreted by _
\bf_
\bs_
\bc_
\bk.
-
\b-b
\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.
-
\b-l
\bl 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.
-
\b-m
\bm 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.
-
\b-y
\by Assume a yes response to all questions asked by _
\bf_
\bs_
\bc_
\bk;
this should be used with great caution as this is a
free license to continue after essentially unlimited
trouble has been encountered.
-
\b-n
\bn Assume a no response to all questions asked by _
\bf_
\bs_
\bc_
\bk
except for ``CONTINUE?'', which is assumed to be
affirmative; do not open the file system for writing.
-
\b-c
\bc 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, _
\bf_
\bs_
\bc_
\bk
will list the direction the conversion is to be made
Printed 7/27/90 February 2
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
_
\bd_
\bu_
\bm_
\bp_
\bf_
\bs(8).
If no filesystems are given to _
\bf_
\bs_
\bc_
\bk then a default list of
file systems is read from the file /
\b/e
\bet
\btc
\bc/
\b/f
\bfs
\bst
\bta
\bab
\bb.
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
3. Incorrect link counts.
Directory size not of proper format.
Partially truncated file.
6. Blocks not accounted for anywhere.
File pointing to unallocated inode.
Inode number out of range.
Dot or dot-dot not the first two entries of a
directory or having the wrong inode number.
More blocks for inodes than there are in the
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 l
\blo
\bos
\bst
\bt+
\b+f
\bfo
\bou
\bun
\bnd
\bd directory. The name assigned is the
inode number. If the _
\bl_
\bo_
\bs_
\bt+_
\bf_
\bo_
\bu_
\bn_
\bd directory does not exist,
it is created. If there is insufficient space its size is
Because of inconsistencies between the block device and the
buffer cache, the raw device should always be used.
/etc/fstab contains default list of file systems
D
\bDI
\bIA
\bAG
\bGN
\bNO
\bOS
\bST
\bTI
\bIC
\bCS
\bS
The diagnostics produced by _
\bf_
\bs_
\bc_
\bk are fully enumerated and
explained in Appendix A of ``Fsck - The UNIX File System
Printed 7/27/90 February 3
S
\bSE
\bEE
\bE A
\bAL
\bLS
\bSO
\bO
fstab(5), fs(5), fsdb(8), newfs(8), mkfs(8), reboot(8)
Printed 7/27/90 February 4
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