HDIUTIL(1) BSD General Commands Manual HDIUTIL(1)
NAME
hdiutil -- manipulate disk images (attach, verify, burn, etc)
SYNOPSIS
hdiutil verb [options]
DESCRIPTION
hdiutil uses the DiskImages framework to manipulate disk images. Common verbs include attach, detach,
verify, create, convert, and burn.
The rest of the verbs are: help, info, load, checksum, chpass, eject (historical synonym for detach),
flatten, unflatten, imageinfo, mount (historical synonym for attach), mountvol, unmount, plugins,
udifrez, internet-enable, resize, segment, compact, makehybrid, and pmap.
COMMON OPTIONS
The following option descriptions apply to all verbs:
-verbose be verbose; default is less output. This option can help the user decipher why a particular
operation failed. At a minimum, the probing of any specified images will be detailed.
-quiet minimize output in most cases. -debug and -verbose negate almost all of -quiet's functional-ity. functionality.
ity.
-debug be very verbose. This option is good if a large amount of information about what hdiutil and
the DiskImages framework are doing is needed. -debug and -verbose generate almost entirely
independent outputs.
Many hdiutil verbs understand the following options:
-plist provide result output in plist format. Other programs invoking hdiutil are expected to
use -plist rather than try to parse the usual output. The usual output will remain con-sistent consistent
sistent but unstructured.
-puppetstrings provide progress output that is easy for another program to parse. Any program trying
to interpret hdiutil's progress should use -puppetstrings.
-srcimagekey key=value
specify a key/value pair for the disk image recognition system. (-imagekey is normally
a synonym)
-tgtimagekey key=value
specify a key/value pair for any image created. (-imagekey is only a synonym if there
is no input image).
-encryption [AES-128|AES-256]
specify a particular type of encryption or, if not specified, the default encryption
algorithm. Two default algorithm is the AES cipher with a 128-bit key.
-stdinpass read a null-terminated passphrase from standard input. If the standard input is a tty,
the passphrase will be read with readpassphrase(3). -stdinpass replaces -passphrase
though the latter is still supported for compatibility. Beware that the password will
contain any newlines before the NULL. See the EXAMPLES section.
-agentpass Used with pubkey option if you need to create an encrypted image protected by both a
public key and a password. A dialog will be shown prompting for a password. This may be
used instead of -stdinpass in this case. This behavior is the default if not specifying
-pubkey
-recover keychain_file
specify a keychain containing the secret corresponding to the certificate specified with
-certificate when the image was created). The correct alternate secret will unlock the
image.
-certificate certificate_file
specify a secondary access certificate for the image being created.
-pubkey PK1,PK2,...,PKn
specify a list of public key hashes in ASCII hex for the image being created. The
hash(s) will be used to locate a public key used to protect an encrypted image.
-cacert cert specify a certificate authority certificate. cert can be either a PEM file or a direc-tory directory
tory of certificates processed by c_rehash(1). See also --capath and --cacert in
curl(1).
-insecurehttp ignore SSL host validation failures. Useful for self-signed servers for which the
appropriate certificates are unavailable or if access to a server is desired when the
server name doesn't match what is in the certificate.
-shadow [shadowfile]
Use a shadow file in conjunction with the data in the image. This option prevents modi-fication modification
fication of the original image and allows read-only images to be attached read/write.
When blocks are being read from the image, blocks present in the shadow file override
blocks in the base image. All data written to the attached device will be redirected to
the shadow file. If not specified, -shadow defaults to image.shadow. If the shadow file
does not exist, it is created. Verbs accepting -shadow also accept -cacert and
-insecurehttp.
Verbs that create images automatically append the correct extension to any filenames if the extension
is not already present. The creation engine also examines the filename extension of the provided file-name filename
name and changes its behavior accordingly. For example, a sparse image can be created without specify-ing specifying
ing -type SPARSEBUNDLE simply by appending the .sparsebundle extension to the provided filename.
VERBS
Each verb is listed with its description and individual arguments. Arguments to the verbs can be
passed in any order. A sector is 512 bytes.
help display minimal usage information for each verb. hdiutil verb -help will provide full usage
information for that verb.
attach image [options]
attach a disk image to the system as a device. attach, like hdid(8), will return informa-tion information
tion about an already-attached image as if it had attached it. mount is a synonym for
attach.
Beware that an image freshly created and attached is treated as a new removable device. See
hdid(8) and the EXAMPLES section below for more details.
NOTE: The format of the output from the attach command is subject to change from release to
release. The normal output displays the disk node, content hint, and mount point (if any).
In particular, writers should NOT rely upon the content hint being the same for a given par-tition partition
tition type; for instance, HFS partitions have the content hint "Apple_HFS" on an image with
an Apple partition map and "48465300-0000-11AA-AA11-0030654" on an image with a GUID parti-tion partition
tion map.
Common options: -encryption, -stdinpass, -recover, -imagekey, -shadow, -puppetstrings, and
-plist.
Options:
-readonly force the resulting device to be read-only
-readwrite attempt to override the DiskImages framework's decision to attach a par-ticular particular
ticular image read-only. For example, -readwrite can be used to modify
the HFS filesystem on a HFS/ISO hybrid CD image.
-nokernel attach with a helper process.
-kernel attempt to attach this image without a helper process; fail if not possi-ble. possible.
ble.
-notremovable prevent this image from being detached. Only root can use this option.
-mount required|optional|suppressed
indicate whether filesystems in the image should be mounted or not. OS X
10.2.x and earlier defaulted to optional behavior; the default is now
required.
-nomount identical to -mount suppressed.
-mountroot path mount volumes in path instead of in /Volumes. path must exist. Note
that mountpoint paths must be less than MNAMELEN characters (90 as of
this writing).
-mountrandom path like -mountroot, but mountpoint names are randomized with mkdtemp(3).
Note that mountpoint paths must be less than MNAMELEN characters (90 as
of this writing).
-mountpoint path assuming only one volume, mount it at path instead of in /Volumes. Note
that mountpoint paths must be less than MNAMELEN characters (90 as of
this writing). See fstab(5) for ways a system administrator can make
particular volumes automatically mount in particular filesystem locations
by editing the file /etc/fstab.
-union perform a union mount
-private suppress mount notifications to the rest of the system. Note that
-private can confuse programs using the Carbon File Manager and should
generally be avoided.
-nobrowse mark the volumes non-browsable in applications such as the Finder.
-owners on|off enable or disable owners for HFS+ volumes, potentially overriding the
system's default value for the volume.
-drivekey key=value
specify a key/value pair to be attached to the device in the IOKit reg-istry. registry.
istry.
The following options have corresponding elements in the com.apple.frameworks.diskimages
preferences domain and thus can be rendered in both the positive and the negative:
-[no]verify do [not] suppress verification of the image. By default, hdiutil attach
verifies all images containing checksums before attaching them. To main-tain maintain
tain backwards compatibility, hdid(8) does not attempt to verify images
before attaching them.
-[no]ignorebadchecksums
specify whether bad checksums should be ignored. The default is to abort
when a bad checksum is detected.
-[no]idme do [not] perform IDME actions on IDME images. IDME actions are normally
only performed when a browser downloads and attaches an image.
-[no]idmereveal do [not] reveal (in the Finder) the results of IDME processing.
-[no]idmetrash do [not] put IDME images in the trash after processing.
-[no]autoopen do [not] auto-open volumes (in the Finder) after attaching an image. By
default, read-only volumes are auto-opened in the Finder.
-[no]autoopenro do [not] auto-open read-only volumes.
-[no]autoopenrw do [not] auto-open read/write volumes.
-[no]autofsck do [not] force automatic file system checking before mounting a disk
image. If fsck is successful and the image can be written, fsck will only
run once on any particular instance of an image.
detach dev_name [-force]
detach a disk image and terminate any associated hdid process. dev_name is a partial /dev
node path (e.g. "disk1"). As of OS X 10.4, dev_name can also be a mount point. If Disk
Arbitration is running, detach will use it to unmount any filesystems and detach the image.
If not, detach will attempt to unmount any filesystems and detach the image directly (using
the `eject' ioctl). If Disk Arbitration is not running, it may be necessary to unmount the
filesystems with umount(8) before detaching the image. eject is a synonym for detach.
Options:
-force Similar to umount -f. Unmounts any filesystems and detaches the image, regardless
of any open files on the image.
verify image [options]
compute the checksum of a read-only (or compressed) image, and verify it against the value
stored in the image. verify accepts the common options -encryption, -stdinpass,
-srcimagekey, -puppetstrings, and -plist.
create size_spec image
create a new image of the given size or from the provided data. If image already exists,
-ov must be specified or create will fail. If image is attached, it must be detached before
it can be overwritten, even if -ov is specified. To make a cross-platform CD or DVD, use
makehybrid. See also EXAMPLES below.
The size specified is the size of the image to be created. Filesystem and partition layout
overhead (64 sectors for the default SPUD layout on PPC machines, 80 sectors for the default
GPTSPUD layout on Intel machines) will be deducted before space is made for user data in any
volume on the image.
Size specifiers:
-size ??b|??k|??m|??g|??t??p|??e
Specify the size of the image in the style of mkfile(8) with the addition of
tera-, peta-, and exa-bytes sizes (note that 'b' specifies a number of sectors,
not bytes). The larger sizes are useful when creating large sparse images.
-sectors sector_count
Specify the size of the image file in 512 byte sectors.
-megabytes size
Specify the size of the image file in megabytes (1024*1024 bytes).
-srcfolder source
Derive the image size from the the filesystem entity source and copy the contents
of source to the resulting image. The filesystem type of the image volume will
match that of the source as closely as possible unless overridden with -fs.
Other size specifiers, such as -size, will override the default (size of the
source directory plus some padding for filesystem overhead), allowing for more or
less free space in the resulting filesystem. -srcfolder copies file by file,
creating a fresh (theoretically defragmented) filesystem on the destination
image. Such an image would be good for use with asr(8). -srcdir is a synonym.
-srcdevice device
specifies that the blocks of device should be used to create a new image. The
image size will match the size of device. resize can be used to adjust the size
of a filesystem in any writable image. Both -srcdevice and -srcfolder can run
into errors if there are bad blocks on a disk. One way around this problem is to
write over the files in question in the hopes that the drive will remap the bad
blocks when it notices them. Data will be lost, but the image creation operation
will subsequently succeed.
Common options: -encryption, -stdinpass, -certificate, -pubkey, -plist, -imagekey,
-tgtimagekey, -puppetstrings, and -plist.
-imagekey di-sparse-puma-compatible=TRUE and -imagekey di-shadow-puma-compatible=TRUE will
create, respectively, sparse and shadow images that can be attached on OS X 10.1. -imagekey
encrypted-encoding-version can select between version 1 and version 2 of the encrypted
encoding. The framework preferences have a corresponding key to change the default for all
images. Version 2 is not compatible with OS X 10.2 but is more robust for SPARSE (UDSP)
images. Version 1 is the default for non-sparse images. As of OS X 10.4.7, sparse,
encrypted images always use version 2.
General options:
-align alignment
specifies a size to which the final data partition will be aligned. The
default is 4K.
-type UDIF|SPARSE|SPARSEBUNDLE
UDIF is the default disk image type. If specified, a UDRW of the specified
size will be created. Specifying SPARSE creates a UDSP: a read/write single-file singlefile
file image which expands as is is filled with data. SPARSEBUNDLE creates a
UDSB: a read/write backed by a directory bundle. The default for UDSP is to
grow one megabyte at a time. The default for UDSB is to create band files of
up to 128 MB. sparse-band-size can be used (with -imagekey) to specify the
number of sectors that will be added each time the image grows. The maximum
size of a sparse image (of either type) is bounded by the filesystem in the
image, the partition map (if any). SPARSE images are additionally bounded by
an internal limit of 128 petabytes. compact can reclaim unused bands in a
UDSP if it has an HFS+ filesystem on it. As an alternative to sparse images,
a UDRW can be resized with resize. See USING PERSISTENT SPARSE IMAGES below
for more information.
-fs filesystem
where filesystem is one of HFS+, HFS+J, HFSX, HFS, MS-DOS, or UFS. -fs will
cause a filesystem of the specified type to be written to the image. -fs may
also change the default layout if that particular filesystem is not native to
an Apple_HFS partition in an Apple Partition Map.
-volname volname
The newly-created filesystem will be named volname. The default name is
`untitled'.
-uid uid the root of the newly-created volume will be owned by the given numeric user
id. 99 maps to the magic `unknown' user (see hdid(8)).
-gid gid the root of the newly-created volume will be owned by the given numeric group
id. 99 maps to `unknown'.
-mode mode the root of the newly-created volume will have mode (in octal) mode.
-[no]autostretch do [not] suppress automatically making stretchable volumes when the volume
size crosses the auto-stretch-size threshold (default: 256 MB). See also
asr(8).
-stretch max_stretch
-stretch initializes HFS+ filesystem data such that it can later be stretched
on older systems (which could only stretch within predefined limits) using
hdiutil resize or by asr(8). max_stretch is specified like -size.
-fsargs newfs_args
additional arguments to pass to whatever newfs program is implied by -fs.
newfs_hfs(8) has a number of options that can reduce the amount of space
needed by the filesystem's data structures. Suppressing the journal with -fs
HFS+ and passing arguments such as -c c=64,a=16,e=16 to -fsargs will minimize
gaps at the front of the filesystem, allowing resize to squeeze more space
from the filesystem. For truly optimal filesystems, makehybrid should be
used.
-layout layout
Specify the partition layout of the image. layout can be anything specified
in MediaKit.framework's MKDrivers.bundle. NONE creates an image with no par-tition partition
tition map. When such an image is attached, a single /dev entry will be cre-ated created
ated (e.g. /dev/disk1). SPUD is an acronym for Single Partition UDIF. SPUD
creates an image with a DDM and an Apple Partition Scheme partition map with
a single entry for an Apple_HFS partition. GPTSPUD creates an image with a
GUID Partition Scheme partition map with a single entry for an Apple_HFS par-tition. partition.
tition. When attached, multiple /dev entries will be created and the 2nd
partition will be the data partition (e.g. /dev/disk1, /dev/disk1s1,
/dev/disk1s2; the second partition is disk1s2). Unless changed by -fs, the
default is SPUD on PPC machines, and GPTSPUD on Intel machines. Other lay-outs layouts
outs include "UNIVERSAL HD" and "UNIVERSAL CD" which add appropriate OS 9
driver partitions for those types of media. OS 9 drivers are not used by OS
X nor by its Classic environment.
-partitionType partition_type
Change the type of partition in a single-partition disk image. The default
is Apple_HFS, though if the layout is not specified, the appropriate parti-tion partition
tion scheme and type will be automatically chosen depending on the argument
to -fs.
-ov overwrite an existing file. The default is not to overwrite existing files.
See the note with create about not being allowed to overwrite attached
images.
-attach attach the image after creating it (plain attach -- use hdiutil attach for
more options). Note that if no filesystem is specified via -fs, the attach
will fail per the default attach -mount required behavior.
Image from source options (for -srcfolder and -srcdevice):
-format format Specify the final image format. The default when a source is specified is
UDZO. format can be any of the format parameters used by convert.
Options specific to -srcdevice:
-segmentSize size_spec
Specify that the image should be written in segments no bigger than size_spec
(which follows -size conventions).
Options specific to -srcfolder:
-[no]crossdev do [not] cross device boundaries on the source filesystem.
-[no]scrub do [not] skip temporary files when imaging a volume with -srcfolder. Scrub-bing Scrubbing
bing is the default when the source is the root of a mounted volume.
Scrubbed items include trashes, temporary directories, swap, etc.
-[no]anyowners do [not] require that the user invoking hdiutil own all of the files in the
source.
-copyuid user perform the copy as the given user. Normally, the copy is performed to
maintain fidelity as explained below.
-skipunreadable skip files that can't be read by the copying user and don't authenticate.
By default, create -srcfolder attempts to maintain the permissions present in the source
directory. It prompts for authentication if it detects an unreadable file, a file owned by
someone other than the user creating the image, or a SGID file in a group that the copying
user is not in.
convert image -format format -o outfile
convert image to type format and write the result to outfile.
As mentioned above, the correct filename extension will be added only if it isn't part of
the provided name. Format is one of:
UDRW - UDIF read/write image
UDRO - UDIF read-only image
UDCO - UDIF ADC-compressed image
UDZO - UDIF zlib-compressed image
UDBZ - UDIF bzip2-compressed image (OS X 10.4+ only)
UFBI - UDIF entire image with MD5 checksum
UDRo - UDIF read-only (obsolete format)
UDCo - UDIF compressed (obsolete format)
UDTO - DVD/CD-R master for export
UDxx - UDIF stub image
UDSP - SPARSE (grows with content)
UDSB - SPARSEBUNDLE (grows with content; bundle-backed)
RdWr - NDIF read/write image (deprecated)
Rdxx - NDIF read-only image (Disk Copy 6.3.3 format)
ROCo - NDIF compressed image (deprecated)
Rken - NDIF compressed (obsolete format)
DC42 - Disk Copy 4.2 image
In addition to the compression offered by some formats, the UDIF and NDIF read-only formats
completely remove unused space in HFS and UFS filesystems. For UDZO, -imagekey
zlib-level=value allows the zlib compression level to be specified ala gzip(1). The default
compression level is 1 (fastest).
Options are any of:
Common options: -encryption, -stdinpass, -certificate, -srcimagekey, -tgtimagekey, -shadow
with friends, -puppetstrings, and -plist.
Other options:
-align alignment
The default is 4 (2K).
-pmap add partition map.
When converting a NDIF to a any variety of UDIF, or when converting an unparti-tioned unpartitioned
tioned UDIF, the default is true.
-segmentSize [size_spec]
Specify segmentation into size_spec-sized segments as outfile is being written.
The default size_spec when -segmentSize is specified alone is 2*1024*1024 (1 GB
worth of sectors) for UDTO images and 4*1024*1024 (2 GB segments) for all other
image types. size_spec can also be specified ??b|??k|??m|??g|??t??p|??e like
create's -size flag.
-tasks task_count
When converting an image into a compressed format, specify the number of
threads to use for the compression operation. The default is the number of
processors active in the current system.
burn image
Burn image to optical media in an attached burning device. In all cases, a prompt for media
will be printed once an appropriate drive has been found. Common options: -shadow with
friends, -srcimagekey, -encryption, -puppetstrings, and -stdinpass.
Other options:
-device specify a device to use for burning. See -list.
-testburn don't turn on laser (laser defaults to on).
-anydevice explicitly allow burning to devices not qualified by Apple (kept for back-wards backwards
wards compatibility as burn will burn to any device by default as of OS X
10.4).
-[no]eject do [not] eject disc after burning. The default is to eject the disc.
-[no]verifyburn do [not] verify disc contents after burn. The default is to verify.
-[no]addpmap do [not] add partition map if necessary. Some filesystem types will not be
recognized when stored on optical media unless they are enclosed in a par-tition partition
tition map. This option will add a partition map to any bare filesystem
which needs a partition map in order to be recognized when burned to opti-cal optical
cal media. The default is to add the partition map if needed.
-[no]skipfinalfree do [not] skip final free partition. If there is a partition map on the
image specifying an Apple_Free partition as the last partition, that
Apple_Free partition will not be burned. The burned partition map will
still reference the empty space. The default is to skip burning a final
free partition.
-[no]optimizeimage do [not] optimize filesystem for burning. Optimization can reduce the
size of an HFS or HFS+ volume to the size of the data contained on the vol-ume. volume.
ume. This option will change what is burned such that the disc will have a
different checksum than the image it came from. The default is to burn all
blocks of the disk image (minus any trailing Apple_Free).
-[no]forceclose do [not] force the disc to be closed after burning. Further burns to the
disc will be impossible. The default is not to close the disc.
-nounderrun Disable the default buffer underrun protection.
-[no]synthesize [Don't] Synthesize a hybrid filesystem for the disc. The default is to
create a new (HFS/ISO) filesystem when the source image's blocks could not
be legally burned to a disc.
-speed x_factor 1, 2, 4, 6, ... `max'
The desired "x-factor". e.g. 8 means the drive will be instructed burn at
"8x speed". `max' will cause the burn to proceed at the maximum speed of
the drive. `max' is the default speed. Slower speeds can produce more
reliable burns. The speed factor is relative to the media being burned
(e.g. -speed 2 has a different data rate when used for a DVD burn vs. a CD
burn). Note that some drives have a minimum burn speed in which case any
slower speed specified will result in a burn at the drive's minimum speed.
-sizequery calculate the size of disc required (the size returned is in sectors) with-out without
out burning anything.
-erase prompt for optical media (DVD-RW/CD-RW) and then, if the hardware supports
it, quickly erase the media. If an image is specified, it will be burned
to the media after the media has been erased.
-fullerase erase all sectors of the disc (this usually takes quit a bit longer than
-erase).
-list list all burning devices, with OpenFirmware paths suitable for -device.
makehybrid -o image source
Generate a potentially-hybrid filesystem in a read-only disk image using the DiscRecording
framework's content creation system.
source can either be a directory or a disk image. The generated image can later be burned
using burn, or converted to another read-only format with convert. By default, the filesys-tem filesystem
tem will be readable on most modern computing platforms. The generated filesystem is not
intended for conversion to read/write, but can safely have its files copied to a read/write
filesystem by ditto(8) or asr(8) (in file-copy mode).
hdiutil supports generating El Torito-style bootable ISO9660 filesystems, which is commonly
used for booting x86-based hardware. The specification includes several emulation modes. By
default, an El Torito boot image emulates either a 1.2MB, 1.44MB, or 2.88MB floppy drive,
depending on the size of the image. Also available are "No Emulation" and "Hard Disk
Emulation" modes, which allow the boot image to either be loaded directly into memory, or be
virtualized as a partitioned hard disk, respectively. The El Torito options should not be
used for data CDs.
Filesystem options:
-hfs Generate an HFS+ filesystem. This filesystem can be present on an image simultane-ously simultaneously
ously with an ISO9660 or Joliet or UDF filesystem. On operating systems that under-stand understand
stand HFS+ as well as ISO9660 and UDF, like Mac OS 9 or Mac OS X, it is usually the
preferred filesystem.
-iso Generate an ISO9660 Level 2 filesystem with Rock Ridge extensions. This filesystem
can be present on an image simultaneously with an HFS+ or Joliet or UDF filesystem.
ISO9660 is the standard cross-platform interchange format for CDs and some DVDs, and
is understood by virtually all operating systems. If an ISO9660 or Joliet filesys-tem filesystem
tem is present on a disk image or CD, but not HFS+, Mac OS X will use the ISO9660
(or Joliet) filesystem.
-joliet Generate Joliet extensions to ISO9660. This view of the filesystem can be present
on an image simultaneously with HFS+, and requires the presence of an ISO9660
filesystem. Joliet supports Unicode filenames, but is only supported on some oper-ating operating
ating systems. If both an ISO9660 and Joliet filesystem are present on a disk image
or CD, but not HFS+, Mac OS X will prefer the Joliet filesystem.
-udf Generate a UDF filesystem. This filesystem can be present on an image simultaneously
with HFS+, ISO9660, and Joliet. UDF is the standard interchange format for DVDs,
although operating system support varies based on OS version and UDF version.
By default, if no filesystem is specified, the image will be created with all four filesys-tems filesystems
tems as a hybrid image. When multiple filesystems are selected, the data area of the image
is shared between all filesystems, and only directory information and volume meta-data are
unique to each filesystem. This means that creating a cross-platform ISO9660/HFS+ hybrid
has a minimal overhead when compared to a single filesystem image.
Other options (most take a single argument):
-hfs-blessed-directory Path to directory which should be "blessed" for Mac OS X booting on
the generated filesystem. This assumes the directory has been other-wise otherwise
wise prepared, for example with bless -bootinfo to create a valid
BootX file. (HFS+ only).
-hfs-openfolder Path to a directory that will be opened by the Finder automatically.
See also the -openfolder option in bless(8) (HFS+ only).
-hfs-startupfile-size Allocate an empty HFS+ Startup File of the specified size, in bytes
(HFS+ only).
-abstract-file Path to a file in the source directory (and thus the root of the gen-erated generated
erated filesystem) for use as the ISO9660/Joliet Abstract file
(ISO9660/Joliet).
-bibliography-file Path to a file in the source directory (and thus the root of the gen-erated generated
erated filesystem) for use as the ISO9660/Joliet Bibliography file
(ISO9660/Joliet).
-copyright-file Path to a file in the source directory (and thus the root of the gen-erated generated
erated filesystem) for use as the ISO9660/Joliet Copyright file
(ISO9660/Joliet).
-application Application string (ISO9660/Joliet).
-preparer Preparer string (ISO9660/Joliet).
-publisher Publisher string (ISO9660/Joliet).
-system-id System Identification string (ISO9660/Joliet).
-keep-mac-specific Expose Macintosh-specific files (such as .DS_Store) in non-HFS+
filesystems (ISO9660/Joliet).
-eltorito-boot Path to an El Torito boot image. By default, floppy drive emulation
is used, so the image must be one of 1200KB, 1440KB, or 2880KB. If
the image has a different size, either -no-emul-boot or
-hard-disk-boot must be used to enable "No Emulation" or "Hard Disk
Emulation" mode, respectively (ISO9660/Joliet).
-hard-disk-boot Use El Torito Hard Disk Emulation mode. The image must represent a
virtual device with an MBR partition map and a single partition
-no-emul-boot Use El Torito No Emulation mode. The system firmware will load the
number of sectors specified by -boot-load-size and execute it, with-out without
out emulating any devices (ISO9660/Joliet).
-no-boot Mark the El Torito image as non-bootable. The system firmware may
still create a virtual device backed by this data. This option is not
recommended (ISO9660/Joliet).
-boot-load-seg For a No Emulation boot image, load the data at the specified segment
address. This options is not recommended, so that the system
firmware can use its default address (ISO9660/Joliet)
-boot-load-size For a No Emulation boot image, load the specified number of 512-byte
emulated sectors into memory and execute it. By default, 4 sectors
(2KB) will be loaded (ISO9660/Joliet).
-eltorito-platform Use the specified numeric platform ID in the El Torito Boot Catalog
Validation Entry or Section Header. Defaults to 0 to identify x86
hardware (ISO/Joliet).
-eltorito-specification For complex layouts involving multiple boot images, a plist-format-ted plist-formatted
ted string can be provided, using either OpenStep-style syntax or XML
syntax, representing an array of dictionaries. Any of the El Torito
options can be set in the sub-dictionaries and will apply to that
boot image only. If -eltorito-specification is provided in addition
to the normal El Torito command-line options, the specification will
be used to populate secondary non-default boot entries.
-udf-version Version of UDF filesystem to generate. This can be either "1.02" or
"1.50". If not specified, it defaults to "1.50" (UDF).
-default-volume-name Default volume name for all filesystems, unless overridden. If not
specified, defaults to the last path component of source.
-hfs-volume-name Volume name for just the HFS+ filesystem if it should be different
(HFS+ only).
-iso-volume-name Volume name for just the ISO9660 filesystem if it should be different
(ISO9660 only).
-joliet-volume-name Volume name for just the Joliet filesystem if it should be different
(Joliet only).
-udf-volume-name Volume name for just the UDF filesystem if it should be different
(UDF only).
-hide-all A glob expression of files and directories that should not be exposed
in the generated filesystems. The string may need to be quoted to
avoid shell expansion, and will be passed to glob(3) for evaluation.
Although this option cannot be used multiple times, an arbitrarily
complex glob expression can be used.
-hide-hfs A glob expression of files and directories that should not be exposed
via the HFS+ filesystem, although the data may still be present for
use by other filesystems (HFS+ only).
-hide-iso A glob expression of files and directories that should not be exposed
via the ISO filesystem, although the data may still be present for
use by other filesystems (ISO9660 only). Per above, the Joliet hier-archy hierarchy
archy will supersede the ISO hierarchy when the hybrid is mounted as
an ISO 9660 filesystem on Mac OS X. Therefore, if Joliet is being
generated (the default) -hide-joliet will also be needed to hide the
file from mount_cd9660(8).
-hide-joliet A glob expression of files and directories that should not be exposed
via the Joliet filesystem, although the data may still be present for
use by other filesystems (Joliet only). Because OS X's ISO 9660
filesystem uses the Joliet catalog if it is available, -hide-joliet
effectively supersedes -hide-iso when the resulting filesystem is
mounted as ISO on OS X.
-hide-udf A glob expression of files and directories that should not be exposed
via the UDF filesystem, although the data may still be present for
use by other filesystems (UDF only).
-only-udf A glob expression of objects that should only be exposed in UDF.
-only-iso A glob expression of objects that should only be exposed in ISO.
-only-joliet A glob expression of objects that should only be exposed in Joliet.
-print-size Preflight the data and calculate an upper bound on the size of the
image. The actual size of the generated image is guaranteed to be
less than or equal to this estimate.
-plistin Instead of using command-line parameters, use a standard plist from
standard input to specific the parameters of the hybrid image genera-tion. generation.
tion. Each command-line option should be a key in the dictionary,
without the leading "-", and the value should be a string for path
and string arguments, a number for number arguments, and a boolean
for toggle options. The source argument should use a key of "source"
and the image should use a key of "output".
If a disk image was specified for source, the image will be attached and paths will be eval-uated evaluated
uated relative to the mountpoint of the image. No absolute paths can be used in this case.
If source is a directory, all argument paths should point to files or directories either via
an absolute path, or via a relative path to the current working directory.
The volume name options, just like files in the filesystems, may need to be mapped onto the
legal character set for a given filesystem or otherwise changed to obey naming restrictions.
Use drutil(1) as drutil filename myname to see how a given string would be remapped.
The -abstract-file, -bibliography-file, -and -copyright-file must exist directly in the
source directory, not a sub-directory, and must have an 8.3 name for compatibility with
ISO9660 Level 1.
compact image
scans the bands of a sparse (SPARSE or SPARSEBUNDLE) disk image containing an HFS filesys-tem, filesystem,
tem, removing those parts of the image which are no longer being used by the filesystem.
Depending on the location of files in the hosted filesystem, compact may or may not shrink
the image. For SPARSEBUNDLE images, completely unused band files are simply removed.
Common options: -encryption, -stdinpass, -srcimagekey, -shadow with friends, -puppetstrings,
and -plist.
info display information about DiskImages.framework, the disk image driver, and any images that
are currently attached. hdiutil info accepts -plist.
load manually load the disk image driver. Normally, the disk image driver is loaded by the
DiskImages framework whenever needed. As of OS X 10.2, the driver will automatically unreg-ister unregister
ister itself after the last image is detached (it will then be unloaded after about a minute
without being used again).
checksum image -type type
Calculate the specified checksum on the image data, regardless of image type.
Common options: -shadow with friends, -encryption, -stdinpass. -srcimagekey,
-puppetstrings, and -plist,
type is one of:
UDIF-CRC32 - CRC-32 image checksum
UDIF-MD5 - MD5 image checksum
DC42 - Disk Copy 4.2
CRC28 - CRC-32 (NDIF)
CRC32 - CRC-32
MD5 - MD5
SHA - SHA
SHA1 - SHA-1
SHA256 - SHA-256
SHA384 - SHA-384
SHA512 - SHA-512
chpass image
change the passphrase for an encrypted image. The default is to change the password inter-actively. interactively.
actively.
Common options: -recover and -srcimagekey. The options -oldstdinpass and -newstdinpass
allow, in the order specified, the null-terminated old and new passwords to be read from the
standard input in the same manner as with -stdinpass.
unflatten image
unflatten a UDIF disk image, creating a dual-fork file in traditional format (resource-only;
no XML). If the resource fork representation of the metadata becomes greater than 16 MB,
the operation will fail with error -39 ("End of fork").
Common options: -encryption, -stdinpass, and -srcimagekey.
flatten image
Flatten a read-only (or compressed) UDIF disk image into a single-fork file. By default,
metadata will be stored both as XML (for the kernel's use) and in an embedded resource fork
(for OS X 10.1 and earlier). Note: UDBZ is not supported in-kernel.
Common options: -srcimagekey, -encryption, and -stdinpass. flatten is only required if the
UDIF has previously been unflattened.
Other options:
-noxml don't embed XML data for in-kernel attachment. The image will never attach in-kernel. inkernel.
kernel.
-norsrcfork don't embed resource fork data. The image will not attach on OS X versions
prior to OS X 10.2.
fsid image
Print information about file systems on a given disk image. As is usually the case, image
can be a /dev entry corresponding to a physical disk. See the NOTE ON DEV ENTRY ACCESS sec-tion. section.
tion. More detailed information is presented for HFS file systems.
Common options: -encryption, -stdinpass, -srcimagekey, and -shadow with friends.
mountvol dev_name
Attempt to mount the filesystem in dev_name using Disk Arbitration (similar to diskutil
mount). XML output is available from -plist. Note that mountvol (rather than mount) will
remount a volume after it has been unmounted by unmount. Images are attached and detached;
volumes are mounted and unmounted. mountvol undoes a unmount operation.
mount/attach can be called on a /dev entry, but it will treat the /dev entry as a disk image
to be attached (creating another /dev entry). This is usually undesirable.
unmount volume [-force]
unmounts a mounted volume without detaching any associated image. volume is a /dev entry or
the name of a mountpoint. NOTE: unmount does NOT detach any disk image associated with the
volume. Images are attached and detached; volumes are mounted and unmounted. mount (which
is a synonym for attach) will NOT remount an image-based volume if the image is already
attached but the volume is not mounted (i.e. if unmount has been used on the filesystem).
mountvol will remount a volume that has been unmounted by unmount.
Options:
-force unmount filesystem regardless of open files on that filesystem. Similar to umount
-f.
imageinfo image
Print out information about a disk image.
Common options: -encryption, -stdinpass, -srcimagekey, -shadow with friends, and -plist.
Options are any of:
-format just print out the image format
-checksum just print out the image checksum
plugins print information about DiskImages framework plugins. The user, system, local, and network
domains are searched for plugins (i.e. ~/Library/Plug-ins/DiskImages,
/System/Library/Plug-ins/DiskImages, /Library/Plug-ins/DiskImages,
/Network/Library/Plug-ins/DiskImages). -plist is available.
internet-enable [-yes] | -no | -query image
Enable or disable post-processing for the image. Without arguments, IDME will be enabled.
If so enabled, upon first encounter with Disk Copy (on OS X 10.2.3+) or a browser using the
feature for a download on OS X 10.3, the image will have its visible contents copied into
the directory containing the image and the image will be put into the trash with IDME turned
off.
Common options: -encryption, -stdinpass, -srcimagekey, and -plist.
resize size_spec image
Resize a disk image or the containers within it. Given a read/write partitioned UDIF, if
the last partition is Apple_HFS, attempt to resize the partition to the end of the image, or
to the last used block in the embedded HFS/HFS+ filesystem (depending on size_spec). On
older systems, resize was limited to pre-defined limits that depended on how the filesystem
was created. As of OS X 10.4, resize can be used to grow an HFS filesystem within an image
to any size supported by HFS and the filesystem hosting the image.
resize is often used when a device image needs to be shrunk so that the HFS/HFS+ partition
can be converted to CD-R/DVD-R format and still be burned. Note that gaps cannot be
reclaimed as resize does not move data. -fsargs can sometimes be used to minimize filesys-tem-generated filesystem-generated
tem-generated gaps. resize can grow a filesystem and image within the bounds of the image
and filesystem formats (e.g. roughly 2^63 bytes for HFS+ inside of a UDRW on HFS+).
hdiutil burn does not burn Apple_Free partitions at the end of the devices, so an image with
a resized filesystem can be burned to create a CD-R/DVD-R master that contains only the
actual data in the hosted filesystem (assuming minimal data fragmentation).
Common options: -encryption, -stdinpass, -srcimagekey, -shadow with friends, and -plist.
Size specifiers:
-size ??b|??k|??m|??g|??t??p|??e
-sectors sector_count | min | max
Specify the number of 512 byte sectors to which the partition should be
resized. If this falls outside the min/max values, an error will be
returned and the partition will not be resized. min automatically deter-mines determines
mines the smallest size the partition can be resized to and uses that
value. max automatically determines the largest size to which the parti-tion partition
tion can be grown and then uses that value.
Other options:
-imageonly only resize the image file, not the partition(s) inside of it. This is the
default for UDIF images (more partitions can then be added in the new free
space).
-partitiononly only resize the partition(s) in the image (including their embedded
filesystems). This is the default for NDIF images. For a newly-created
single partition disk image where the partition fills the image, the parti-tion partition
tion can only be shrunk. If there is an Apple_Free partition after an
existing partition, that partition can be expanded into the space marked by
the Apple_Free. Shrinking a partition results in a larger Apple_Free par-tition. partition.
tition.
-partitionNumber partitionNumber
specifies which partition to resize (UDIF only -- see HISTORY below).
partitionNumber is 0-based, but, per hdiutil pmap, partition 0 is the par-tition partition
tition map itself.
-growonly only allow the image to grow
-shrinkonly only allow the image to shrink
-nofinalgap allow resize to entirely eliminate the trailing free partition. Such an
image restored to a hard drive will not boot OS 9 nor will it allow OS X to
boot on old-world (beige) machines.
-limits Displays the minimum, current, and maximum sizes (in 512 byte sectors) that
could be passed given possible -imageonly or -partitiononly flags. In
addition to any filesystem constraints, the maximum size is limited by
available disk space for UDRW images. Does not modify the image.
-oldlimits behaves like -limits except that it reports the stretch sizes that OS X
version 10.3 would have reported (useful if an image needs to be used with
asr(8) on an older system).
segment
segment -o firstSegname -segmentCount #segs image [opts]
segment -o firstSegname -segmentSize size image [opts]
segment a NDIF or UDIF disk image. Segmented images work around limitations in file size
which are sometimes imposed by filesystems, network protocols, or media. Note: whether or
not the segments are encrypted is determined by the options passed to segment and not by the
state of the source image.
Common options: -encryption, -stdinpass, -srcimagekey, -tgtimagekey, -puppetstrings, and
-plist.
Options:
-segmentCount segment_count
Specify the number of segments. Only one of -segmentCount or -segmentSize will
be honored.
-segmentSize segment_size
Specify the segment size in sectors or in the style of mkfile(8) (here unquali-fied unqualified
fied numbers are still sectors). If the original image size is not an exact
multiple of the segment size, the last segment will be shorter than the others.
Only one of -segmentCount or -segmentSize will be honored. Segmenting
read/write (UDRW) images is not supported (as of OS X 10.3).
-firstSegmentSize segment_size
Specify the first segment size in sectors in the same form as for -segmentSize.
Used for multi-CD restores.
-restricted Make restricted segments for use in multi-CD restores.
-ov overwrite any existing files. See notes with create about not being allowed to
overwrite attached images, etc.
pmap image_source [-options optstr]
display the partition map of an image or device. image_source is either a plain file or
special file (i.e. a /dev/disk entry). See the NOTE ON DEV ENTRY ACCESS below.
Common options: -encryption, -stdinpass, -srcimagekey, and -shadow with friends.
optstr defaults to "xsSgcvk" and can be any combination of the following:
r raw - process all without modification
x extended - process 2K & 512 entries and merge
s sectorize - return all quantities in sectors
S sort - sort all entries by block number
g genfree - account for all unmapped space
c combfree - combine adjacent freespace entries
f fixfinal - extend last partition to device end
v volume synthesize - synthesize single volumes as
a single partition entry
k skip zero-length - skip zero length entries
K skip void/free - skip all free & void partitions
m merge free space - Merge small free partitions into a previous
partition if possible
i ignore shims - ignore small free partitions caused by block
alignment
udifrez [options] image
Attaches resources (software license agreements, for example) to a disk image.
You must specify one of the following options:
-xml inputfile
Copy resources from an XML file.
-rsrcfork inputfile
Copy resources from the resource fork of a file.
You must also specify two files:
image
the disk image you wish to modify.
inputfile
a file containing the resources you wish to attach.
EXAMPLES
Verifying:
hdiutil verify myimage.img
Verifies an image against its internal checksum.
Segmenting:
hdiutil segment -segmentSize 10m -o /tmp/aseg 30m.dmg
creates aseg.dmg, aseg.002.dmgpart, and aseg.003.dmgpart
Converting:
hdiutil convert master.dmg -format UDTO -o master
Converts master.dmg to a CD-R export image, appending .toast to the filename.
hdiutil convert CDmaster.dmg -format UDTO -o CDmaster.cdr
Converts CDmaster.dmg to a CD-R export image named CDmaster.cdr.
hdiutil convert /dev/disk1 -format UDRW -o devimage
Converts the disk /dev/disk1 to a read/write device image file. authopen(1) will
be used if read access to /dev/rdisk1 is not available. Note use of the block-special
device.
Burning:
hdiutil burn myImage.dmg
Burns the image to available optical media and verifies the burn.
hdiutil burn myRawImage.cdr -noverifyburn -noeject
Burns the image without verifying the burn or ejecting the disc. Volumes will be
mounted after burning.
Creating a 50 MB encrypted image:
hdiutil create -encryption -size 50m e.dmg -fs HFS+J
Creating a 50 MB encrypted image protected with public key only:
hdiutil create -encryption -size 50m e.dmg -fs HFS+J
-pubkey F534A3B0C2AEE3B988308CC89AA04ABE7FDB5F30
Creating a 50 MB encrypted image protected with public key and password:
hdiutil create -encryption -size 50m e.dmg -fs HFS+J -agentpass
-pubkey F534A3B0C2AEE3B988308CC89AA04ABE7FDB5F30
Creating an encrypted single-partition (Apple Partition Map on PPC and GUID Partition Scheme on Intel)
disk image without user interaction:
echo -n pp|hdiutil create -encryption -stdinpass -size 9m sp.dmg
Creating a "1 GB" SPARSE image (a 1 GB filesystem in a growable file):
hdiutil create -type SPARSE -size 1g -fs HFS+ growableTo1g
Creating a "1 GB" SPARSEBUNDLE (a 1 GB filesystem in a growable bundle):
hdiutil create -type SPARSEBUNDLE -size 1g -fs HFS+ growableTo1g
Creating a new mounted volume backed by an image:
hdiutil create -volname Dick -size 1.3m -fs HFS -attach Moby.dmg
Using a shadow file to attach a read-only image read-write to modify it, then convert it back to a
read-only image. This method eliminates the time/space required to convert a image to read-write before
modifying it.
hdiutil attach -owners on Moby.dmg -shadow
/dev/disk2 Apple_partition_scheme
/dev/disk2s1 Apple_partition_map
/dev/disk2s2 Apple_HFS /Volumes/Moby
ditto /Applications/Preview.app /Volumes/Moby
hdiutil detach /dev/disk2
hdiutil convert -format UDZO Moby.dmg -shadow
Using makehybrid. Given the files:
albumlist.txt song2.wma song4.m4a song6.mp3 song8.mp3
song1.wma song3.m4a song5.mp3 song7.mp3
Create an HFS+/ISO9660/Joliet hybrid MusicBackup.iso with some common content between filesystems. The
HFS+ filesystem, typically only visible on Macintosh systems, will not include the .wma files, but will
show the .m4a and .mp3 files. The Joliet filesystem will not show the .m4a and .mp3 files, but will
show the .wma files. The ISO9660 filesystem, typically the default filesystem for optical media on many
platforms, will only show the .mp3 files. All three filesystems will include the "albumlist.txt" files.
The -hide options take glob expressions as expanded by glob(3).
hdiutil makehybrid -o MusicBackup.iso Music -hfs -iso -joliet \
-hide-hfs 'Music/*.wma' -hide-joliet 'Music/{*.m4a,*.mp3}' \
-hide-iso 'Music/*.{wma,m4a}'
(see also drutil(1) for making CD audio discs)
Image from directory (new-style):
hdiutil create -srcfolder mydir mydir.dmg
Image from directory (10.1-style; of historical interest):
du -s myFolder # du(1) will count resource forks
10542
hdiutil create -sectors 10642 folder # add ~1% for filesytem
hdid -nomount folder.dmg
...
/dev/disk1s2 Apple_HFS
newfs_hfs -v myFolderImage /dev/rdisk1s2
hdiutil detach disk1
hdid folder.dmg
...
/dev/disk1s2 Apple_HFS /Volumes/myFolderImage
sudo mount -u -t hfs -o perm /dev/disk1s2 /Volumes/myFolderImage
# optionally enable owners; sudo unneeded if manually mounted
ditto -rsrcFork myFolder /Volumes/myFolderImage
hdiutil detach disk1s2 # all done
hdiutil convert -format UDZO -o folder.z.dmg folder.dmg # compress
Manually changing ownership settings of a read-only disk image:
hdiutil attach myimage.dmg
...
/dev/disk1s2 Apple_HFS /Volumes/myVolume
sudo mount -ur -t hfs -o perm /dev/disk1s2 /Volumes/myVolume
# what if I prefer using /sbin/mount
disktool -p disk1s2 # try 'diskutil unmount' on Panther
mkdir /Volumes/myVolume
Forcing a known image to attach:
hdiutil attach -imagekey diskimage-class=CRawDiskImage myBlob.bar
ENVIRONMENT
The following environment variables affect hdiutil and DiskImages:
com_apple_hdid_verbose
enable -verbose behavior for attach.
com_apple_hdid_debug
enable -debug behavior for attach.
com_apple_hdid_nokernel
similar to -nokernel but works even with, for example, create -attach.
com_apple_hdid_kernel
attempt to attach in-kernel first (like attach -kernel). In OS X 10.4.x, in-kernel was the
default behavior for UDRW and SPARSE images. On OS X 10.5, these and other kernel-compati-ble kernel-compatible
ble images, including RAM-based images described in hdid(8), will attach with a user process
unless attach --kernel is used or the corresponding variable is set. If an image is not
"kernel-compatible" and -kernel is specified, the attach will fail. (WARNING: ram:// images
currently use wired memory when attached in-kernel).
com_apple_diskimages_insecureHTTP
disable SSL peer verification the same way -insecurehttp does. Useful for clients of
DiskImages such as asr(8) which don't support a similar command line option.
ERRORS
DiskImages uses many frameworks and can encounter many error codes. In general, it tries to turn these
errors numbers into localized strings for the user. For background, intro(2) is a good explanation of
the initial error domain, the BSD errno values. For debugging, -verbose should generally provide
enough information to figure out what has gone wrong. The following is a list of interesting errors
that hdiutil may encounter:
[ENXIO] Device not configured. This error is returned by DiskImages when its kernel driver
or framework helper cannot be contacted. The former usually means the IOHDIXCon-troller IOHDIXController
troller kernel extension can't be loaded. The latter usually means Foundation's
distributed objects RPC mechanism cannot be configured. DO doesn't work under dead
mach bootstrap contexts such as exist in a reattached screen(1) session. Root users
can take advantage of StartupItemContext(8) (in /usr/libexec) to access the startup
item mach bootstrap context.
[EINVAL] Invalid argument. This error is used in many contexts and is often a clue that
hdiutil's arguments are subtly non-sensical (e.g. an invalid layout name passed to
create -layout).
[EFBIG] File too large. DiskImages uses this error explicitly when attempting to access a
disk image over HTTP that is too large for the server to support Range requests.
See hdid(8) for more details.
[EAUTH] Authentication error. Used by DiskImages when libcurl(3) is unable to verify its
SSL peer. See -insecurehttp for more information.
[EBUSY] Resource busy. Used if necessary exclusive access cannot be obtained. For example,
returned by create -ov when the image is attached.
EACCES vs. EPERM
EACCES and EPERM are subtly different. The latter "operation not permitted" tends
to refer to an operation that cannot be performed, often due to an incorrect effec-tive effective
tive user ID. On the other hand, "permission denied" tends to mean that a particu-lar particular
lar access mode prevented the operation.
USING PERSISTENT SPARSE IMAGES
As of OS X 10.5, a more reliable, efficient, and scalable sparse format, UDSB (SPARSEBUNDLE), is recom-mended recommended
mended for persistent sparse images as long as a backing bundle (directory) is acceptable. SPARSE
(USSP) images and shadow files were designed for intermediate use when creating other images (e.g.
UDZO) when final image sizes are unknown. As of OS X 10.3.2, partially-updated SPARSE images are prop-erly properly
erly handled and are thus safe for persistent storage. SPARSE images are not recommended for persis-tent persistent
tent storage on versions of OS X earlier than 10.3.2 and should generally only be used when data sizes
are truly unknown. resize can resize an HFS+ filesystem and the image containing it.
If more space is needed than is referenced by the hosted filesystem, create -stretch and resize can
help to grow or shrink the filesystem in the image. compact reclaims unused space in the image.
Beware that sparse images can enhance the effects of any fragmentation in the filesystem.
To prevent errors when a filesystem inside of a sparse image has more free space than the volume hold-ing holding
ing the sparse image, HFS volumes inside sparse images will report an amount of free space slightly
less than the amount of free space on the volume on which image resides. The image filesystem cur-rently currently
rently only behaves this way as a result of a direct attach action and will not behave this way if, for
example, the filesystem is unmounted and remounted (e.g. with unmount and mountvol).
NOTE ON DEV ENTRY ACCESS
Since any /dev entry can be treated as a raw disk image, it is worth noting which devices can be
accessed when and how. /dev/rdisk nodes are character-special devices, but are "raw" in the BSD sense
and force block-aligned I/O. They are closer to the physical disk than the buffer cache. /dev/disk
nodes, on the other hand, are buffered block-special devices and are used primarily by the kernel's
filesystem code.
It is not possible to read from a /dev/disk node while a filesystem is mounted from it, but anyone with
read access to the appropriate /dev/rdisk node can use hdiutil verbs such as fsid on it. The DiskIm-ages DiskImages
ages framework will attempt to use authopen(1) to open any device which it can't open (due to EACCES)
for reading with open(2). This may cause apparent hangs while trying to access /dev entries while
logged in remotely (an authorization panel is waiting on console).
Generally, the /dev/disk node is preferred for imaging devices (e.g. convert or create -srcfolder
operations), while /dev/rdisk is usable for the quick pmap or fsid. In particular, converting the
blocks of a mounted journaled filesystem to a read-only image will prevent the volume in the image from
mounting (the journal will be permanently dirty).
COMPATIBILITY
OS X 10.0 supported the disk images of Disk Copy 6 on Mac OS 9. OS X 10.1 added sparse, encrypted, and
zlib-compressed images. These images will not be recognized on OS X 10.0 (or will attach read/write,
possibly allowing for their destruction). As the sparse, shadow, and encrypted formats have evolved,
switches have been added to facilitate the creation of images that are compatible with older OS ver-sions versions
sions (at the expense of the performance and reliability improvements offered by the format enhance-ments). enhancements).
ments). In particular, sparse images should not be expected to attach on versions of OS X older than
that which created them.
With OS X 10.2, the most common image formats went "in-kernel" (i.e. the DiskImages kernel extension
served them without a helper process), image meta-data began being stored both as XML and in the embed-ded embedded
ded resource fork, and the default Disk Copy.app "compressed" format became UDZO (breaking compatibil-ity compatibility
ity with 10.0). OS X 10.4 introduced bzip2 compression in the UDBZ format which provides smaller
images (especially when combined with makehybrid) at the expense of backwards compatibility.
In OS X 10.4.7, the resource forks previously embedded in UDIF images were abandoned entirely to avoid
metadata length limitations imposed by resource fork structures. As a result, UDIF images created on
10.4.7 and later will not be recognized by either OS X 10.1 or OS X 10.0. flatten can be used to cus-tomize customize
tomize the type of metadata stored in the image. OS X 10.5 introduced sparse bundle images which
compact very efficiently.
HISTORY
Disk images were first invented to electronically store and transmit representations of floppy disks
for manufacturing replication. These images of floppies are typically referred to as 'Disk Copy 4.2'
images, in reference to the application that created these images and restored them to floppy disks.
Disk Copy 4.2 images were block for block representations of a floppy disk, with no notion of compres-sion. compression.
sion. DART is a variant of the Disk Copy 4.2 format that supported compression of the floppy image.
NDIF (New Disk Image Format) images were developed to replace the Disk Copy 4.2 and DART image formats
and to support images larger than a floppy disk. With NDIF and Disk Copy version 6, images could be
"attached" as mass storage devices under Mac OS 9. Apple Data Compression (ADC) -- which carefully
optimizes for fast decompression -- was used to compress images that were typically created once and
restored many times during manufacturing.
UDIF (Universal Disk Image Format) device images picked up where NDIF left off, allowing images to rep-resent represent
resent entire block devices and all the data therein: DDM, Apple partition scheme partition map, disk-based diskbased
based drivers, etc. For example, it can represent bootable CD's which can then be replicated from an
image. To be single-forked (vs. the dual-fork NDIF), it began storing its metadata in an embedded
resource. UDIF is the native image format for OS X.
Raw disk images from other operating systems (e.g. .iso files) will be recognized as disk images and
can be attached and mounted if OS X recognizes the filesystems. They can also be burned with hdiutil
burn.
WHAT'S NEW
In OS X 10.3, most Disk Copy functionality moved to Disk Utility and a new background application
DiskImageMounter handles attaching images.
As of OS X 10.4, encrypted images (such as those used for FileVault) can be attached without a helper
process and "image from folder" operations no longer require more disk space than the final image.
Images containing exotic-to-CD filesystems (such as MS-DOS) can have their files burned with burn
-synthesize. Significant hdiutil changes in 10.4 include the addition of -puppetstrings to many verbs,
-anydevice becoming the default for burn, and signal handlers so that hdiutil can try to clean up
before quitting when canceled. And in OS X 10.4.7, all read-only UDIFs (including the compressed
types) began being handled by a helper process to free up resources in the kernel.
SEE ALSO
authopen(1), hdid(8), diskutil, ditto(8), load_hdi(8), ioreg(8), drutil(1), ufs.util(8), msdos.util(8),
hfs.util(8), diskarbitrationd(8), /usr/sbin/disktool (run with no arguments for usage),
/System/Library/CoreServices/DiskImageMounter.app.
Mac OS X 03 Aug 2007 Mac OS X
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