Mar 16, 2018 Software for Apple’s OS X platform comes in package files, and these packages make installing software extremely simple. This was one of the advances that came with the Unix-core OS X is based on. Users should always check to make sure that they know what’s in a package they’ve downloaded before installing it. Jul 02, 2020 Format: Choose APFS or Mac OS Extended (Journaled). Disk Utility shows a compatible format by default. Disk Utility shows a compatible format by default. If you see an Erase Volume Group button, the volume you selected is part of a volume group.
Sometimes, if your Mac doesn’t recognize a file type as something that one of its programs can handle, or if you want a specific file type to always open in a specific program, Mac OS X Lion might need a little help from you. Mac OS X Lion lets you specify the application in which you want to open a document in the future when you double-click it. Suppose that you want all .tif graphic files that usually open in Preview to open instead in Pixelmator, a more capable third-party program
More than that, you can specify that you want all documents of that type to open with the specified application. “Where is this magic bullet hidden?” you ask. Right there in the file’s Info window.
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Mach-O, short for Machobject file format, is a file format for executables, object code, shared libraries, dynamically-loaded code, and core dumps. A replacement for the a.out format, Mach-O offers more extensibility and faster access to information in the symbol table.
Mach-O is used by most systems based on the Mach kernel. NeXTSTEP, macOS, and iOS are examples of systems that use this format for native executables, libraries and object code.
Mach-O file layout[edit]
Each Mach-O file is made up of one Mach-O header, followed by a series of load commands, followed by one or more segments, each of which contains between 0 and 255 sections. Mach-O uses the REL relocation format to handle references to symbols. When looking up symbols Mach-O uses a two-level namespace that encodes each symbol into an 'object/symbol name' pair that is then linearly searched for by first the object and then the symbol name.[1]
The basic structure—a list of variable-length 'load commands' that reference pages of data elsewhere in the file[2]—was also used in the executable file format for Accent.[citation needed] The Accent file format was in turn, based on an idea from Spice Lisp.[citation needed]
Multi-architecture binaries[edit]
Under NeXTSTEP, OPENSTEP, macOS, and iOS, multiple Mach-O files can be combined in a multi-architecture binary. This allows a single binary file to contain code to support multiple instruction set architectures. For example, a multi-architecture binary for iOS can have 6 instruction set architectures, namely ARMv6 (for iPhone, 3G and 1st / 2nd generation iPod touch), ARMv7 (for iPhone 3GS, 4, 4S, iPad, 2, 3rd generation and 3rd–5th generation iPod touch), ARMv7s (for iPhone 5 and iPad (4th generation)), ARMv8 (for iPhone 5S), x86 (for iPhone simulator on 32-bit machines) and x86_64 (64-bit simulator).[citation needed]
File System For Mac OsMinimum OS version[edit]
With the introduction of Mac OS X 10.6 platform the Mach-O file underwent a significant modification that causes binaries compiled on a computer running 10.6 or later to be (by default) executable only on computers running Mac OS X 10.6 or later. The difference stems from load commands that the dynamic linker, in previous Mac OS X versions, does not understand. Another significant change to the Mach-O format is the change in how the Link Edit tables (found in the __LINKEDIT section) function. In 10.6 these new Link Edit tables are compressed by removing unused and unneeded bits of information, however Mac OS X 10.5 and earlier cannot read this new Link Edit table format. To make backwards-compatible executables, the linker flag '-mmacosx-version-min=' can be used.
Other implementations[edit]![]()
Some versions of NetBSD have had Mach-O support added as part of an implementation of binary compatibility, which allowed some Mac OS 10.3 binaries to be executed.[3][4]
For Linux, a Mach-O loader was written by Shinichiro Hamaji[5] that can load 10.6 binaries. As a more extensive solution based on this loader, the Darling Project aims at providing a complete environment allowing OS X applications to run on Linux.
For the Ruby programming language, the ruby-macho[6] library provides an implementation of a Mach-O binary parser and editor.
See also[edit]References[edit]Mac Os Drive Formats
Mac Os Standard FormatExternal links[edit]
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Mach-O&oldid=935419343'
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