Manual page for fsck_ufs(1M)
fsck_ufs - file system consistency check and interactive repair
fsck -F ufs
fsck -F ufs
audits and interactively repairs inconsistent conditions on file
systems. A file system to be checked may be specified by giving the name
of the block or character
device or by giving the name of its mount
point if a matching entry exists in
represents the block or character special
device (for example,
on which the file system resides.
In general, the character special device should be used.
will not work on a block device if the block device is mounted,
unless the file system is error-locked.
device is specified, all
file systems specified in the
entry will be checked. If the
option is specified,
file systems with an
number greater than one are checked in parallel.
In the case of correcting serious inconsistencies, by default,
asks for confirmation before making a repair and waits for the operator to
If the operator does not have write
permission on the file system,
will default to a
corrections) action. See
Repairing some file system inconsistencies may result in loss of data. The
amount and severity of data loss may be determined from the diagnostic
automatically corrects innocuous inconsistencies such as
unreferenced inodes, too-large link counts in inodes, missing blocks in the
free list, blocks appearing in the free list and also in files, or
incorrect counts in the super block automatically. It displays a message
for each inconsistency corrected that identifies the nature of the
correction on which the file system took place. After successfully
correcting a file system,
prints the number of files on that
file system, the number of used and free blocks, and the percentage of
Inconsistencies checked are as follows:
Blocks claimed by more than one inode or the free list.
- Blocks claimed by an inode or the free list outside the range of the file system.
- Incorrect link counts.
- Incorrect directory sizes.
- Bad inode format.
- Blocks not accounted for anywhere.
- Directory checks, file pointing to unallocated inode,
inode number out of range, absence of
as the first two entries in each directory.
- Super Block checks:
more blocks for inodes than there are in the file system.
- Bad free block list format.
- 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
The name assigned is the inode number. If the
directory does not exist, it is created.
If there is insufficient space in the
directory, its size is increased.
consist of the following options:
Check but do not repair. This option checks that the file system
is suitable for mounting, returning the appropriate exit status.
If the file system is ready for mounting,
displays a message such as:
ufs fsck: sanity check: /dev/rdsk/c0t3d0s1 okay
response to all questions asked by
do not open the file system for writing.
Echo the expanded command line, but do not execute the command.
This option may be used to verify and validate the command line.
response to all questions asked by
for the details for specifying
- -o specific-options
file system specific options.
These options can be any combination of the
following separated by commas (with no intervening spaces).
as the super block for the file system.
Block 32 is always one of the alternate super blocks. The location of
other super blocks may be determined by running
If the file system is in the old (static table) format,
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
file system configuration.
In interactive mode,
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 file system.
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 converted at once.
The format of a file system can be
determined from the first line of output from
It should be noted that the
option is seldom used and is included
only for compatibility with pre-4.1 releases. There is no guarantee
that this option will be included in future releases.
Force checking of file systems regardless of the
state of their super block clean flag.
(``preen'') Check and fix the file system non-interactively.
Exit immediately if there is a problem requiring intervention.
This option is required to enable parallel file system checking.
Check writable file systems only.
list of default parameters for each file system
The operating system buffers file system data. Running
on a mounted file system can cause the operating system's buffers
to become out of date with respect to the disk. For this reason,
the file system should be
If this is
not possible, care should be taken that the system is quiescent and that
it is rebooted immediately after
Quite often, however, this will not be sufficient. A panic will probably
occur if running
on a file system modifies the file system.
It is usually faster to check the character special device than the
block special device.
Created by unroff & hp-tools.
© by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97