FSCK_HFS(8) – System Manager’s Manual

NAME

fsck_hfs – HFS file system consistency check

SYNOPSIS

fsck_hfs
-q
[-df]
special …
fsck_hfs
-p
[-df]
special …
fsck_hfs
[-n | -y | -r]
[-dfgxlES]
[-D flags]
[-b size]
[-B path]
[-m mode]
[-c size]
[-R flags]
special …

DESCRIPTION

The
fsck_hfs
utility verifies and repairs standard HFS and HFS+ file systems.

The first form of
fsck_hfs
quickly checks the specified file systems to determine whether
they were cleanly unmounted.

The second form of
fsck_hfs
preens the specified file systems.
It is normally started by
fsck(8)
run from
/etc/rc.boot
during automatic reboot, when a HFS file system is detected.
When preening file systems,
fsck_hfs
will fix common inconsistencies for file systems that were not
unmounted cleanly.
If more serious problems are found,
fsck_hfs
does not try to fix them, indicates that it was not
successful, and exits.

The third form of
fsck_hfs
checks the specified file systems and tries to repair all
detected inconsistencies.

If no options are specified
fsck_hfs
will always check and attempt to fix the specified file systems.

The options are as follows:

-c size

Specify the
size
of the cache used by
fsck_hfs
internally. Bigger
size
can result in better performance but can result in deadlock when
used with
-l
option. Size can be specified as a decimal, octal, or
hexadecimal number. If the number ends with a “k”, “m”,
or “g”, the number is multiplied by 1024 (1K), 1048576 (1M),
or 1073741824 (1G), respectively.

-d

Display debugging information.
This option may provide useful information when
fsck_hfs
cannot repair a damaged file system.

-D flags

Print extra debugging information. The
flags
are a bitmap that control which kind of debug information is printed.
The following values are currently implemented:

0x0001

Informational messages

0x0002

Error messages

0x0010

Extended attributes related messages

0x0020

Overlapped extents related messages

-b size

Specify the size, in bytes, of the physical blocks used by the
-B
option.

-B path

Print the files containing the physical blocks listed in the file
path.
The file should contain one or more decimal, octal (with leading 0) or
hexadecimal (with leading 0x) numbers separated by white space. The physical
block numbers are relative to the start of the partition, so if you
have block numbers relative to the start of the device, you will have to
subtract the block number of the start of the partition. The size of a
physical block is given with the
-b
option; the default is 512 bytes per block.

-f

When used with the
-p
option, force
fsck_hfs
to check `clean’ file systems, otherwise it means force
fsck_hfs
to check and repair journaled HFS+ file systems.

-g

Causes
fsck_hfs
to generate its output strings in GUI format.
This option is used when another application with a graphical user interface
(like Mac OS X Disk Utility) is invoking the
fsck_hfs
tool.

-x

Causes
fsck_hfs
to generate its output strings in XML (plist) format. This option
implies the
-g
option.

-l

Lock down the file system and perform a test-only check.
This makes it possible to check a file system that is currently mounted,
although no repairs can be made.

-m mode

Mode is an octal number that will be used to set the permissions for the
lost+found directory when it is created.
The lost+found directory is only created when a volume is repaired and orphaned
files or directories are detected.
fsck_hfs
places orphaned files and directories into the lost+found directory (located
at the root of the volume).
The default mode is 01777.

-p

Preen the specified file systems.

-q

Causes
fsck_hfs
to quickly check whether the volume was unmounted cleanly.
If the volume was unmounted cleanly, then the exit status is 0.
If the volume was not unmounted cleanly, then the exit status will be non-zero.
In either case, a message is printed to standard output describing whether the
volume was clean or dirty.

-y

Always attempt to repair any damage that is found.

-n

Never attempt to repair any damage that is found.

-E

Cause
fsck_hfs
to exit (with a value of 47) if it encounters any
major errors. A “major error” is considered one which
would impact using the volume in normal usage; an inconsistency
which would not impact such use is considered “minor” for this
option. Only valid with the
-n
option.

-S

Cause
fsck_hfs
to scan the entire device looking for I/O errors. It will
attempt to map the blocks with errors to names, similar to
the
-B
option.

-R flags

Rebuilds the requested btree. The following flags are supported:

a

Attribute btree

c

Catalog btree

e

Extents overflow btree

Rebuilding a btree will only
work if there is enough free space on the file system for the new btree
file, and if
fsck_hfs
is able to traverse each of the nodes in the requested btree successfully.
Rebuilding btrees is not supported on HFS Standard volumes.

-r

Rebuild the catalog btree. This is synonymous with
-Rc.

Because of inconsistencies between the block device and the buffer cache,
the raw device should always be used.

EXIT VALUES

fsck_hfs
indicates some status by exit value. The current list of exit status results
is:

0

No errors found, or successfully repaired.

3

A quick-check (the
-n
option) found a dirty filesystem; no repairs were made. There is a potential
corruption in the filesystem, and either the journal could not be read, or a
runtime corruption was present so the HFS Volume Inconsistent bit was set.

4

During boot, the root filesystem was found to be dirty; repairs were
made, and the filesystem was remounted. The system should be rebooted.

8

A corrupt filesystem was found during a check, or repairs did not succeed.

47

A major error was found with
-E.

SEE ALSO

fsck(8)

BUGS

fsck_hfs
is not able to fix some inconsistencies that it detects.

HISTORY

The
fsck_hfs
command appeared in Mac OS X Server 1.0 .

Mac OS X – August 5, 2008