Executable and Link Format (ELF) is a common file format used for executables, shared libraries, and core dumps in Linux and other Unix-like operating systems. It was developed in the early 1990s by the Unix System Laboratories as part of the Portable Operating System Interface (POSIX) application programming interface. The ELF format is used for the Linux kernel, GNU Tools, and many other software components of the Unix-like operating systems.
The ELF file format contains program header tables, section header tables, segment tables, and section header string tables. The purpose of these tables is to provide information to the system loader and linker about the executable, shared library, or object file in which they are contained. Program header tables describe the memory layout of the program and how it should be executed. Section header tables and segment tables describe how each section of the program should be located in memory. The section header string table provides symbolic information, which eliminates the need to hard-code addresses into the program.
ELF also includes relocation information, which allows the program to be linked with other libraries or modules without having to recompile and re-link the entire executable. The dynamic linking provides advantages such as decreased memory usage, faster program loading, and more flexibility for the user.
ELF is a well-defined, standardized format, allowing for portability of programs and libraries across multiple operating systems. It is an object code format defined in the System V Application Binary Interface (ABI). The flexibility of the ELF format has allowed it to become the lingua franca of the computing industry, as it provides a platform-agnostic way to package and deploy software.
