fsck_ffs(8)

NAME

fsck_ffs, fsck_ufs - file system consistency check and in

teractive repair

SYNOPSIS

fsck_ffs   [-BFpfny]   [-b   block]  [-c  level]  [-m  mode]
filesystem ...

DESCRIPTION

The specified disk partitions and/or file systems are

checked. In
"preen" mode the clean flag of each file system's superblock

is examined
and only those file systems that are not marked clean are

checked. File
systems are marked clean when they are unmounted, when they

have been
mounted read-only, or when fsck_ffs runs on them successful

ly. If the -f
option is specified, the file systems will be checked re

gardless of the
state of their clean flag.

The kernel takes care that only a restricted class of in

nocuous file system inconsistencies can happen unless hardware or software

failures
intervene. These are limited to the following:

Unreferenced inodes
Link counts in inodes too large
Missing blocks in the free map
Blocks in the free map also in files
Counts in the super-block wrong

These are the only inconsistencies that fsck_ffs with the -p

option will
correct; if it encounters other inconsistencies, it exits

with an abnormal return status and an automatic reboot will then fail.

For each corrected inconsistency one or more lines will be printed iden

tifying the
file system on which the correction will take place, and the

nature of
the correction. After successfully correcting a file sys

tem, fsck_ffs
will print the number of files on that file system, the num

ber of used
and free blocks, and the percentage of fragmentation.

If sent a QUIT signal, fsck_ffs will finish the file system

checks, then
exit with an abnormal return status that causes an automatic

reboot to
fail. This is useful when you want to finish the file sys

tem checks during an automatic reboot, but do not want the machine to come

up multiuser
after the checks complete.

If fsck_ffs receives a SIGINFO (see the ``status'' argument

for stty(1))
signal, a line will be written to the standard output indi

cating the name
of the device currently being checked, the current phase

number and
phase-specific progress information.

Without the -p option, fsck_ffs audits and interactively re

pairs inconsistent conditions for file systems. If the file system is

inconsistent
the operator is prompted for concurrence before each correc

tion is
attempted. It should be noted that some of the corrective

actions which
are not correctable under the -p option will result in some

loss of data.
The amount and severity of data lost may be determined from

the diagnostic output. The default action for each consistency correc

tion is to
wait for the operator to respond yes or no. If the operator

does not
have write permission on the file system fsck_ffs will de

fault to a -n
action.

The following flags are interpreted by fsck_ffs:

-F Determine whether the file system needs to be

cleaned immediately

in foreground, or if its cleaning can be deferred to

background.
To be eligible for background cleaning it must have

been running
with soft updates, not have been marked as needing a

foreground
check, and be mounted and writable when the back

ground check is
to be done. If these conditions are met, then

fsck_ffs exits
with a zero exit status. Otherwise it exits with a

non-zero exit
status. If the file system is clean, it will exit

with a nonzero exit status so that the clean status of the

file system can
be verified and reported during the foreground

checks. Note that
when invoked with the -F flag, no cleanups are done.

The only
thing that fsck_ffs does is to determine whether a

foreground or
background check is needed and exit with an appro

priate status
code.

-B A check is done on the specified and possibly active

file system.

The set of corrections that can be done is limited

to those done
when running in preen mode (see the -p flag). If

unexpected
errors are found, the file system is marked as need

ing a foreground check and fsck_ffs exits without attempting

any further
cleaning.

-b Use the block specified immediately after the flag

as the super

block for the file system. An alternate super block

is usually
located at block 32 for UFS1, and block 160 for

UFS2.

-c Convert the file system to the specified level.

Note that the

level of a file system can only be raised. There

are currently
four levels defined:

0 The file system is in the old (static table)

format.

1 The file system is in the new (dynamic

table) format.

2 The file system supports 32-bit uid's and

gid's, short

symbolic links are stored in the inode, and

directories
have an added field showing the file type.

3 If maxcontig is greater than one, build the

free segment

maps to aid in finding contiguous sets of

blocks. If
maxcontig is equal to one, delete any exist

ing segment
maps.

In interactive mode, fsck_ffs will list the conver

sion 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 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 dumpfs(8).

-f Force fsck_ffs to check `clean' file systems when

preening.

-m Use the mode specified in octal immediately after

the flag as the

permission bits to use when creating the lost+found

directory
rather than the default 1777. In particular, sys

tems that do not
wish to have lost files accessible by all users on

the system
should use a more restrictive set of permissions

such as 700.

-n Assume a no response to all questions asked by

fsck_ffs except

for `CONTINUE?', which is assumed to be affirmative;

do not open
the file system for writing.

-p Preen file systems (see above).

-y Assume a yes response to all questions asked by

fsck_ffs; this

should be used with great caution as this is a free

license to
continue after essentially unlimited trouble has

been encountered.

Inconsistencies checked are as follows:

1. Blocks claimed by more than one inode or the free map.
2. Blocks claimed by an inode outside the range of the

file system.
3. Incorrect link counts.
4. Size checks:
Directory size not a multiple of DIRBLKSIZ.
Partially truncated file.

5. Bad inode format.
6. Blocks not accounted for anywhere.
7. Directory checks:
File pointing to unallocated inode.
Inode number out of range.
Directories with unallocated blocks (holes).
Dot or dot-dot not the first two entries of a di

rectory or
having the wrong inode number.

8. Super Block checks:
More blocks for inodes than there are in the file

system.
Bad free block map format.
Total free block and/or free inode count incor

rect.

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 insuf

ficient space
its size is increased.

FILES

/etc/fstab contains default list of file systems to check.

EXIT STATUS DIAGNOSTICS

The diagnostics produced by fsck_ffs are fully enumerated

and explained
in Appendix A of Fsck - The UNIX File System Check Program.

SEE ALSO

fs(5), fstab(5), fsck(8), fsdb(8), newfs(8), reboot(8)

BSD April 24, 2001

BSD