What is an OUT file?

The .out file format is typically associated with compiled executable files, particularly in Unix and Linux environments. These files are the output of compilation processes where source code, usually written in languages like C or C++, is compiled into machine code that can be executed by the system.

Key features related to the .out file format include:

  • Compilation Result: It’s generated when the source code is compiled using compilers like gcc. By default, the output file is named a.out unless specified otherwise.
  • Executable: The .out file contains the machine code and is ready for execution in Unix/Linux systems.
  • Platform Specific: These files are typically not portable across different operating systems because they are compiled for specific system architectures.

Common Usage:

  • Developers create .out files during the software development process to test and run compiled code.
  • These files can be renamed or given custom extensions, but the default is .out for historical reasons, tracing back to early Unix systems.

Characteristics of .out Files

Executable Code

The primary purpose of an .out file is to serve as an executable file that can be run on Unix/Linux systems. When source code written in languages like C or C++ is compiled, the resulting .out file contains machine code that the operating system can execute.

Shared Libraries and Object Code

In addition to executable code, .out files can also contain shared libraries and object code. Shared libraries are collections of code that multiple programs can use, promoting code reusability and reducing memory consumption. Object code, on the other hand, is the output of compiling a single source file but is not yet a complete executable.

Default Naming Convention

The .out file format is most commonly associated with the filename “a.out.” This default name is given when no specific name is applied during the compilation process. While “a.out” originally referred to the assembler output format, it has become a general term for compiled output files in many Unix-like systems.

Historical Context

The .out file format has a rich history, tracing back to the days of early computing with the PDP-7 and PDP-11 minicomputers. These machines relied heavily on assembly language programming, and the output from assemblers needed a standardized format. Thus, “a.out” was adopted to represent the output files generated from these programs.

While .out files played a crucial role in the early days of Unix and assembly programming, they have largely been replaced by newer formats like COFF (Common Object File Format). COFF offers improved structure, flexibility, and portability across different platforms. This transition reflects the advancements in software development practices and the need for more robust file formats in modern programming.

How to open or run OUT file

To execute an .out file in a Unix-like environment, you can use the following command in the terminal:

./a.out

This command runs the compiled executable, assuming you are in the directory containing the .out file. If the file has been renamed, simply replace a.out with the appropriate filename.

Programs that can handle OUT files include:

  • Linux (Free)