Mach-O

Also known as .o, .dylib, .bundle, Mach object, MachO

Mach-O (Mach object) is a file format for executables, object code, shared libraries, dynamically loaded code, and core dumps. It was developed to replace the a.out format.

Wikidata facts

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file extension: o
software version identifier: 64bit
described at URL: web.archive.org/web/20090819232456/http://developer.apple.com/documentation/DeveloperTools/Conceptual/MachORuntime/index.html
file format identification pattern: FEEDFACF

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~40 min read

Article

24 sections

Contents

File layout
Header
Multi-architecture binaries
Load commands
Segment load command
Segment number and section numbers
Link libraries
Link library ordinal numbers
__LINKEDIT symbol table
Symbol table organization
__LINKEDIT Symbol table information
Indirect table
__LINKEDIT Compressed table
Binding information
Application main entry point
Application UUID number
Minimum OS version
Other implementations
Mach-O parsers and editors
Mach-O runners
See also
References
Bibliography
External links

Mach-O (Mach object) is a file format for executables, object code, shared libraries, dynamically loaded code, and core dumps. It was developed to replace the a.out format.

Mach-O is used by some 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.