fsck_hfs(8) BSD System Manager's Manual fsck_hfs(8)
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 sys-
tems.
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 speci-
fied 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 deci-
mal, 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 for-
mat. 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 cur-
rently mounted, although no repairs can be made.
-m mode Mode is an octal number that will be used to set the per-
missions 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 encoun-
ters 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.
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 Mac OS X
Mac OS X 10.9 - Generated Thu Oct 17 07:38:46 CDT 2013