SysIII/usr/src/man/man1/fsck.1m

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.TH FSCK 1M
.SH NAME
fsck \- file system consistency check and interactive repair
.SH SYNOPSIS
.B /etc/fsck
[
.B \-y
] [
.B \-n
] [
.BR \-s X
] [
.BR \-S X
] [
.B \-t
file
] [
file-system 
] ...
.SH DESCRIPTION
.I  Fsck\^
audits and interactively repairs inconsistent conditions
for \s-1UNIX\s+1 file systems. 
If the file system is consistent then the number of files, number of blocks
used, and number of blocks free are reported.
If the file system is inconsistent the operator is prompted for concurrence
before each correction is attempted.
It should be noted that most corrective actions 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 \fByes\fP or \fBno\fP.
If the operator does not have write permission 
.I fsck\^
will default to a 
.BR "\-n " action.
.PP
.I Fsck\^
has more consistency checks than
its predecessors
.IR check ,
.IR dcheck ,
.IR fcheck ,
and
.I icheck\^
combined.
.PP
The following flags are interpreted by
.IR fsck .
.TP 6
.B  \-y
Assume a yes response to all questions asked by 
.IR fsck .
.TP 6
.B  \-n
Assume a no response to all questions asked by 
.IR fsck ;
do not open the file system for writing.
.TP 6
.BR \-s \fIX
Ignore the actual free list and (unconditionally) reconstruct a new
one by rewriting the super-block of the file system.  
The file system should be unmounted while this is done; if this
is not possible, care should be taken that the system is quiescent
and that it is rebooted immediately afterwards.
This precaution is necessary so that the old, bad, in-core copy
of the superblock will not continue to be used, or written on the file system.
.IP
The
.BR \-s \fIX
option allows for creating an optimal free-list organization.
The following forms of
.I X\^
are supported for the following devices:
.sp
.nf
	\-s3 (\s-1RP\s+1\&03)
	\-s4 (\s-1RP\s+1\&04, \s-1RP\s+1\&05, \s-1RP\s+1\&06)
	\-sBlocks-per-cylinder\fB:\fRBlocks-to-skip (for anything else)
.fi
.IP "" 6
If 
.I X\^
is not given,
the values used when the file system was created
are used.
If these values were not specified, then the value
.IB 400 : 9
is used.
.TP 6
.BR \-S \fIX
Conditionally reconstruct the free list. This option
is like
.BR \-s \fIX
above except that the free list is rebuilt only
if there were no discrepancies discovered in the
file system. Using
.B \-S
will force a no response to all questions asked
by
.IR fsck .
This option is useful for forcing free list reorganization
on uncontaminated file systems.
.TP 6
.B \-t
If
.I fsck\^
cannot obtain enough memory to keep its tables,
it uses a scratch file. If the \f3\-t\fP option is
specified, the file named in the next argument
is used as the scratch file, if needed. Without the
.BR "\-t " flag,
.I fsck\^
will prompt the operator for the name of the
scratch file. The file chosen should not be on the
file system being checked, and if it is not
a special file or did not already exist, it is
removed when
.I fsck\^
completes.
.PP
If no
.I file-systems\^
are specified,
.I fsck\^
will read a list of default file systems from
the file
.BR /etc/checklist .
.PP
.ne 10
Inconsistencies checked are as follows:
.TP 6
1.
Blocks claimed by more than one inode or the free list.
.br
.br
.ns
.TP 6
2.
Blocks claimed by an inode or the free list outside the range of the file system.
.br
.br
.ns
.TP 6
3.
Incorrect link counts.
.br
.br
.ns
.TP 6
4.
Size checks:
.br
.ns
.IP "" 12
Incorrect number of blocks.
.br
Directory size not 16-byte aligned.
.br
.br
.ns
.TP 6
5.
Bad inode format.
.br
.br
.ns
.TP 6
6.
Blocks not accounted for anywhere.
.br
.br
.ns
.TP 6
7.
Directory checks:
.br
.br
.ns
.IP "" 12
File pointing to unallocated inode.
.br
Inode number out of range.
.br
.br
.ns
.TP 6
8.
Super Block checks:
.br
.br
.ns
.IP "" 12
More than 65536 inodes.
.br
More blocks for inodes than there are in the file system.
.br
.br
.ns
.TP 6
9.
Bad free block list format.
.br
.br
.ns
.TP 6
10.
Total free block and/or free inode count incorrect.
.PP
Orphaned files and directories (allocated but unreferenced) are,
with the operator's concurrence, reconnected by
placing them in the 
.B lost+found
directory.
The name assigned is the inode number.
The only restriction
is that the directory 
.B lost+found
must preexist
in the root of the file system being checked and
must have empty slots in which entries can be made.
This is accomplished by making 
.BR lost+found ,
copying a number of files to the directory, and then removing them
(before
.I
fsck
is executed).
.PP
Checking the raw device is almost always faster.
.SH FILES
.br
.ns
.TP 21
/etc/checklist
contains default list of file systems to check.
.SH DIAGNOSTICS
The diagnostics produced by 
.I fsck\^
are intended to be self-explanatory.
.SH "SEE ALSO"
checklist\^(5), fs\^(5), crash\^(8).
.SH BUGS
Inode numbers for
.BR . ""
and
.BR .. ""
in each directory should be checked for validity.
.PP
\f3\-g\fP and \f3\-b\fP options from 
.I check\^
should be available in
.IR fsck .