NAME

fsck_ufs − file system consistency check and interactive repair

SYNOPSIS

fsck −F ufs [ generic_options ] [ special ... ]
fsck −F ufs [ generic_options ] [ −o specific-options ] [ special ... ]

DESCRIPTION

fsck 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 special device or by giving the name of its mount point if a matching entry exists in /etc/vfstab.  If no special device is specified, all ufs file systems specified in the vfstab with a fsckdev entry will be checked.  If the −p (“preen”) option is specified, ufs file systems with an fsck pass number greater than one are checked in parallel.  See fsck(1M). 

In the case of correcting serious inconsistencies, by default, fsck asks for confirmation before making a repair and waits for the operator to respond either yes or no.  If the operator does not have write permission on the file system, fsck will default to a −n (no corrections) action. See fsck(1M). 

Repairing some file system inconsistencies may result in loss of data.  The amount and severity of data loss may be determined from the diagnostic output. 

fsck 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, fsck prints the number of files on that file system, the number of used and free blocks, and the percentage of fragmentation. 

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 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 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 in the lost+found directory, its size is increased. 

OPTIONS

See generic fsck(1M) for generic_options and details for specifying special.

−o Specify ufs file system specific options.  These options can be any combination of the following separated by commas (with no intervening spaces). 

b=n Use block n 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 newfs(1M) with the −Nv options specified. 

c 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 filesystem configuration.  In interactive mode, fsck 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 filesystem.  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 fstyp()

f Force checking of file systems regardless of the state of their super block clean flag. 

p (“preen”) Check and fix the filesystem non-interactively.  Exit immediately if there is a problem requiring intervention.  This option is required to enable parallel file system checking. 

w Check writable file systems only. 

FILES

/etc/vfstab list of default parameters for each file system

SEE ALSO

crash(1M), fsck(1M), mkfs(1M), newfs(1M), fs_ufs(4)

NOTES

It is usually faster to check the character special device than the block special device. 

SunOS 5.1  —  Last change: 18 Dec 1991