fsck(1m) DG/UX 4.30 fsck(1m)
NAME
fsck - DG/UX file system consistency check and interactive
repair
SYNOPSIS
/etc/fsck [ -y ] [ -n ] [ -p ] [ -q ] [ -x ] [ -D ] [ -f ] [
-s ] [ -S ] [ -t scratch_file ] [ special ... ]
DESCRIPTION
Fsck checks file systems and corrects inconsistencies.
Special is the pathname of a special file referring to a
device containing a file system; the default is the standard
set of special files listed in /etc/checklist. If no
/etc/checklist exists, /etc/fstab is used.
If you wish to check several file systems at once, omit
special and specify the -p option. The /etc/fstab file
contains a pass number and a mounting status for each file
system. When using this file, fsck checks only those file
systems that have a non-zero pass number and a "rw" or "ro"
mounting status. The order of file system checking is based
on pass number, starting at 1.
To save time, have fsck check file systems on disks run by
different controllers on the same pass. To do this, make
the pass number for each of these file systems the same in
/etc/fstab.
Invoking the Fsck Program
There are two ways that fsck is invoked:
Startup script This is the most common way of invoking
fsck. When you are in multi-user mode
bringing up the system with the init
command, you can automatically execute
fsck from within your startup script.
Command line From the command line, you type: fsck
[options] [filesystem_names].
OPTIONS
All options are represented by single-character flags;
options must begin with a hyphen (-). All options except
for -t are boolean flags, and may thus be combined: fsck
-pxD, for example.
The following options are interpreted by fsck:
-p Detect all possible inconsistencies, but correct only
those inconsistencies that may be expected to occur
from an abnormal system halt. For each corrected
inconsistency, one or more lines will be printed
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identifying the file system and the nature of the
correction. Any other inconsistencies will cause the
check of that file system to fail. The following 15
inconsistencies (and only those listed) will be
corrected for the specified file systems:
1. An inode has an incorrect count of the blocks it
uses. The count is corrected.
2. An inode is partially truncated. This can occur
if the system is abnormally halted while a file is
being truncated, leaving it claiming more data
blocks than its size in bytes would require. The
extra blocks are freed.
3. A directory has an incorrect child count. The
count is corrected.
4. A directory entry exists for an inode which is
unallocated. The directory entry is removed.
5. A directory entry's filename length is incorrect.
The length is corrected.
6. An inode is unreferenced (has no directory entries
anywhere in the file system). The inode is
reconnected in the /lost+found directory.
7. No /lost+found directory exists, but an inode
needs to be reconnected there. The directory is
created.
8. The root directory needs to be expanded in order
to make room for a directory entry for lost+found.
The directory is expanded.
9. The /lost+found directory needs to be expanded in
order to make room for a directory entry for an
inode being reconnected there. The directory is
expanded.
10. An inode's link count is incorrect. The count is
corrected.
11. The root control point directory's resource
accounting (blocks, inodes) is incorrect. The
counts are corrected.
12. A disk allocation region (DAR) has an incorrect
free-block bitmap. The bitmap is corrected.
13. A DAR has an incorrect free-inode list. The list
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is corrected.
14. A DAR has incorrect summary counts of used blocks,
inodes or directories. The counts are corrected.
15. The summary counts in the superblock are
incorrect. The counts are corrected.
-q Repair the inconsistencies listed under the -p option
automatically, without asking for user approval.
Unlike -p, however, more serious inconsistencies will
not cause fsck to fail; the user must still answer the
resulting queries.
-y Audit and interactively repair all file system
inconsistencies assuming a "yes" response to all
questions asked by fsck. This option should be used
with great caution, since it could lead to irreversible
changes to the filesystem.
-n Audit and interactively repair all file system
inconsistencies, assuming a "no" response to all
questions asked by fsck. This option also means that
all file systems will be opened with read-only intent.
-x File systems are examined before being checked. If a
file system is marked mountable in its superblock, then
it is not checked.
-s Ignore the actual free-block bitmap and unconditionally
reconstruct a new one.
-S Conditionally reconstruct the free-block bitmap. It is
reconstructed if and only if the file system is
consistent. This option also forces a "no" response to
all questions.
-t Use the specified scratch file for temporary storage if
fsck cannot obtain enough memory. The scratch filename
must be the next argument after -t.
-D Directories are checked for bad blocks.
-f Fast check: blocks and sizes are checked; the free
block bitmap is reconstructed if necessary.
The following options are mutually exclusive, and use of
more than one per invocation is not allowed: -y, -n, -p,
-q, -S.
Checking
Fsck checks for the following inconsistencies: Checking
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proceeds without any input from the operator if no errors
are discovered. When a fatal inconsistency is discovered,
no further checking is done on that file system; fsck either
exits or proceeds to the next specified file system. When
an inconsistency is discovered with the -p option, and that
error is one of those listed under -p, the inconsistency if
fixed without operator approval. Any other discoveries of
inconsistencies require the operator to make a decision.
The fsck program prompts with its recommended action. If
you answer yes, then fsck takes the recommended action. In
no case will any damaging action be taken without approval.
Note, however, that advance approval or disapproval may be
given by invoking fsck with the -y and -n options,
respectively.
The fsck program checks for the following inconsistencies.
Note that the term "Bad format" refers to system blocks that
do not have the required self-identification information.
* Unreadable or inconsistent superblocks.
* Bad format in superblocks.
* Invalid contents in superblock's reserved area.
* Bad value for superblock's file system size.
* Bad value for superblock's DAR size.
* Bad value for superblock's inode/DAR density.
* Bad value for superblock's default data element size.
* Bad value for superblock's default index element size.
* Bad value for superblock's default directory data
element size.
* Bad value for superblock's default directory index
element size.
* Bad value for superblock's default first allocation
threshold.
* Bad value for superblock's default second allocation
threshold.
* Bad format in inode table block.
* Invalid contents in inode's reserved area.
* Files of unknown type.
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* Files with bad fragment size.
* Files which are partially truncated.
* Files claiming impossible blocks.
* Files claiming system-area blocks.
* Bad Index-block format.
* Files with incorrect block counts.
* Files claiming already-claimed blocks.
* Unallocated root inode.
* Bad file type for root.
* Incorrect resource limit information in root.
* Incorrect parent directory in root.
* Directories with "holes" (unallocated blocks before
end-of-file).
* Bad format in directory blocks.
* Directories with invalid information in reserved areas.
* Directories with empty blocks at end.
* Directories with incorrect child counts.
* Extra directory entries named "." or "..".
* Directory entries with invalid characters in filenames:
"/" or non-ASCII characters.
* Directory entries whose pathnames are too lengthy.
* Directory entries that are out of order.
* Directory entries with incorrect entry lengths.
* Directory entries with incorrect filename lengths.
* Extraneous hard links to directories (including cycles
in file system name space).
* Extraneous hard links to symbolic link files.
* Directory entries to invalid inodes.
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* Directory entries to unallocated inodes.
* Files with incorrect space parent.
* Unconnected files or directories.
* Bad or missing lost+found directories.
* Bad lost+found directory entries.
* Root or lost+found directories needing expansion.
* Files with incorrect link counts.
* Incorrect resource allocation counts in control point
directories.
* Bad format in DAR blocks.
* Invalid contents in reserved area of DAR blocks.
* Incorrect free-block bitmaps in DARs.
* Incorrect or incomplete free-inode lists in DARs.
* Incorrect DAR summary counts: blocks used, inodes used,
directories used.
* Incorrect superblock summary counts.
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
(decimal) inode number preceded by the # character.
Checking the character-special device (/dev/rdsk/*) is
almost always faster then checking the block-special device
(/dev/dsk/*).
FILES
/etc/fstab Default list of file systems to check
SEE ALSO
crash(1m), mkfs(1m), fs(4), fstab(4), crash(8)
Installing and Managing the DG/UX System
NOTES
Fsck works sequentially from the pass numbers listed in
/etc/fstab, that is, it begins at 1 and then runs all other
passes in order. There is no way to start an fsck -p at
pass n, where n is an arbitrary number.
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