fsck_ufs(1M)

fsck_ufs -- filesystem consistency check and interactive repair

Synopsis

fsck [-F ufs] [generic_options] [special ...]

fsck [-F ufs] [generic_options] [(-y|-Y)|(-n|-N)] [-o p,b=blkno] [-w] [special . . .]

Description

generic_options are options supported by the generic fsck command.

fsck audits and interactively repairs inconsistent conditions on filesystems. In this case, it asks for confirmation before attempting any corrections. Inconsistencies other than those mentioned above can often result in some loss of data. The amount and severity of data lost can be determined from the diagnostic output.

fsck corrects innocuous inconsistencies such as: unreferenced inodes, incorrect link count of 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, and file system on which, the correction is to take place. After successfully correcting a filesystem, fsck prints the number of files on that filesystem, the number of used and free blocks, and the percentage of fragmentation.

The default action for each correction is to wait for the operator to respond either yes or no. If the operator does not have write permission on the filesystem, fsck will default to a -n (no corrections) action.

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 ``.'' and ``..'' as the first two entries in each directory.
Super Block checks: more blocks for inodes than there are in the filesystem.
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 lost+found directory. The name assigned is the inode number. If the lost+found directory does not exist, it is created. If there is insufficient space its size is increased.

A filesystem may be specified by giving the name of the block or character special device on which it resides, or by giving the name of its mount point.

ufs-specific options

-F ufs

Specify the ufs FSType. If -F ufs is not specified heuristics similiar to those used by fstyp(1M) are used to determine the file system type.

NOTE: This command executes faster if it is not required to autodetect file system types. If possible, specify the -F ufs.

-y | -Y

Assume a yes response to all questions asked by fsck.

-n | -N

Assume a no response to all questions asked by fsck; do not open the filesystem for writing.

-o

Specify the options specific to the ufs filesystem. These options can be any combination of the following:

p: Check the filesystem non-interactively. Exit if there is a problem requiring intervention.
b=blkno: Use blkno as the super block for the filesystem. Block 32 is always an alternate super block.
-w: Only check writeable filesystems.

References

crash(1M), fs_ufs(4), generic fsck(1M), fstyp(1M), generic mkfs(1M)

Notices

Checking the character special device is almost always faster.