This article is about a general type of computer file. For the specific file type used in some operating systems, see .exe.
In computing, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instructions",[2] as opposed to a data file that must be interpreted (parsed) by a program to be meaningful.[3]
A hex dump of an executable real mode loader. The first column consists of addresses of the first byte in the second column, which comprises bytes of data in hexadecimal notation (least significant byte first), and the last column consists of the corresponding ASCII form.[1]
The exact interpretation depends upon the use. "Instructions" is traditionally taken to mean machine code instructions for a physical CPU.[4] In some contexts, a file containing scripting instructions (such as bytecode) may also be considered executable.
Executable files can be hand-coded in machine language, although it is far more convenient to develop software as source code in a high-level language that can be easily understood by humans. In some cases, source code might be specified in assembly language instead, which remains human-readable while being closely associated with machine code instructions.
The high-level language is compiled into either an executable machine code file or a non-executable machine code – object file of some sort; the equivalent process on assembly language source code is called assembly. Several object files are linked to create the executable. Object files -- executable or not -- are typically stored in a container format, such as Executable and Linkable Format (ELF) or Portable Executable (PE) which is operating system-specific.[5] This gives structure to the generated machine code, for example dividing it into sections such as .text (executable code), .data (initialized global and static variables), and .rodata (read-only data, such as constants and strings).
Executable files typically also include a runtime system, which implements runtime language features (such as task scheduling, exception handling, calling static constructors and destructors, etc.) and interactions with the operating system, notably passing arguments, environment, and returning an exit status, together with other startup and shutdown features such as releasing resources like file handles. For C, this is done by linking in the crt0 object, which contains the actual entry point and does setup and shutdown by calling the runtime library.[6]
Executable files thus normally contain significant additional machine code beyond that directly generated from the specific source code. In some cases, it is desirable to omit this, for example for embedded systems development, or simply to understand how compilation, linking, and loading work. In C, this can be done by omitting the usual runtime, and instead explicitly specifying a linker script, which generates the entry point and handles startup and shutdown, such as calling main to start and returning exit status to the kernel at the end.[7]
Executionedit
In order to be executed by the system (such as an operating system, firmware[citation needed], or boot loader), an executable file must conform to the system's application binary interface (ABI). In simple interfaces, a file is executed by loading it into memory and jumping to the start of the address space and executing from there.[8] In more complicated interfaces, executable files have additional metadata specifying a separate entry point. For example, in ELF, the entry point is defined in the header's e_entry field, which specifies the (virtual) memory address at which to start execution.[9] In the GNU Compiler Collection, this field is set by the linker based on the _start symbol.[10]
^Mueller, John Paul (2007). Windows Administration at the Command Line for Windows Vista, Windows 2003, Windows XP, and Windows 2000. John Wiley & Sons. p. 24. ISBN978-0-470-04616-6. Retrieved 2023-03-06.
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This article is about a general type of computer file For the specific file type used in some operating systems see exe In computing executable code an executable file or an executable program sometimes simply referred to as an executable or binary causes a computer to perform indicated tasks according to encoded instructions 2 as opposed to a data file that must be interpreted parsed by a program to be meaningful 3 A hex dump of an executable real mode loader The first column consists of addresses of the first byte in the second column which comprises bytes of data in hexadecimal notation least significant byte first and the last column consists of the corresponding ASCII form 1 The exact interpretation depends upon the use Instructions is traditionally taken to mean machine code instructions for a physical CPU 4 In some contexts a file containing scripting instructions such as bytecode may also be considered executable Contents 1 Generation of executable files 2 Execution 3 See also 4 References 5 External linksGeneration of executable files editSee also Object file Executable files can be hand coded in machine language although it is far more convenient to develop software as source code in a high level language that can be easily understood by humans In some cases source code might be specified in assembly language instead which remains human readable while being closely associated with machine code instructions The high level language is compiled into either an executable machine code file or a non executable machine code object file of some sort the equivalent process on assembly language source code is called assembly Several object files are linked to create the executable Object files executable or not are typically stored in a container format such as Executable and Linkable Format ELF or Portable Executable PE which is operating system specific 5 This gives structure to the generated machine code for example dividing it into sections such as text executable code data initialized global and static variables and rodata read only data such as constants and strings Executable files typically also include a runtime system which implements runtime language features such as task scheduling exception handling calling static constructors and destructors etc and interactions with the operating system notably passing arguments environment and returning an exit status together with other startup and shutdown features such as releasing resources like file handles For C this is done by linking in the crt0 object which contains the actual entry point and does setup and shutdown by calling the runtime library 6 Executable files thus normally contain significant additional machine code beyond that directly generated from the specific source code In some cases it is desirable to omit this for example for embedded systems development or simply to understand how compilation linking and loading work In C this can be done by omitting the usual runtime and instead explicitly specifying a linker script which generates the entry point and handles startup and shutdown such as calling main to start and returning exit status to the kernel at the end 7 Execution editIn order to be executed by the system such as an operating system firmware citation needed or boot loader an executable file must conform to the system s application binary interface ABI In simple interfaces a file is executed by loading it into memory and jumping to the start of the address space and executing from there 8 In more complicated interfaces executable files have additional metadata specifying a separate entry point For example in ELF the entry point is defined in the header s e entry field which specifies the virtual memory address at which to start execution 9 In the GNU Compiler Collection this field is set by the linker based on the start symbol 10 See also editComparison of executable file formats Executable compression Executable textReferences edit Celovi Paul 2002 Embedded FreeBSD Cookbook Elsevier pp 108 187 188 ISBN 1 5899 5004 6 Retrieved 2022 03 06 executable Merriam Webster s Online Dictionary Merriam Webster Retrieved 2008 07 19 Mueller John Paul 2007 Windows Administration at the Command Line for Windows Vista Windows 2003 Windows XP and Windows 2000 John Wiley amp Sons p 24 ISBN 978 0 470 04616 6 Retrieved 2023 03 06 Machine Instructions GeeksforGeeks 2015 11 03 Retrieved 2019 09 18 Chapter 4 Object Files refspecs linuxbase org Retrieved 2019 09 18 Fisher Tim List of Executable File Extensions lifewire com Retrieved 2019 09 18 McKellar Jessica 2010 03 16 Hello from a libc free world Part 1 Smith James E Nair Ravi 2005 05 16 The Architecture of Virtual Machines Computer 38 5 33 34 doi 10 1109 MC 2005 173 Rusling David A 1999 Chapter 4 Processes The Linux Kernel sec 4 8 1 ELF Retrieved 2023 03 06 Page Daniel 2009 A Practical Introduction to Computer Architecture Springer Science Business Media pp 415 416 ISBN 978 1 84882 255 9 Retrieved 2023 03 06 External links editEXE File Format at What Is Retrieved from https en wikipedia org w index php title Executable amp oldid 1204167544, wikipedia, wiki, book, books, library,
