NAME

fsck (ufs) − file system consistency check and interactive repair

SYNOPSIS

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

DESCRIPTION

generic_options are options supported by the generic fsck command.  current_options are options supported by the s5-specific module of the fsck ­command. 

fsck audits and interactively repairs inconsistent conditions on file systems.  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, 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, and file system on which, the correction is to take 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. 

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 file system, 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 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 its size is increased. 

A file system 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. 

The options are:

−F ufs Specifies the ufs-FSType. 

−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 file system for writing. 

−o Specify ufs file system specific suboptions.  These suboptions can be any combination of the following:

p Check the filesystem non-interactively.  Exit if there is a problem requiring intervention. 

b=# Use the block specified as the super block for the file system.  Block 32 is always an alternate super block. 

NOTES

Checking the character special device is almost always faster.  To specify the file system, the raw device or mount point names may be used, but not the block device name. 

SEE ALSO

checkfsys(1M), crash(1M), generic fsck(1M), mkfs(1M), ufs(4)

  —  UFS