fsck(1m)
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fsck
DG/UX file system consistency check and interactive repair
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SYNTAX
/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
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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 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.
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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 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 file's name 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.
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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 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 (the
term ``Bad format'' refers to system blocks which 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
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threshold.
* Bad format in inode table block.
* Invalid contents in inode's reserved area.
* Files of unknown type.
* 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 which have too-long pathnames.
* Directory entries which are out of order.
* Directory entries with incorrect entry lengths.
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* 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.
* 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
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fsck(1m)
/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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