Elf files

ELF means Executable and Linking Format. It is a file format executables, shared libraries, core dumps and object codes. It is now a competitor to other formats like a..out(Assembler Output) and COFF(Common Object File Format) in Unix based operating systems and even in non Unix based operating systems.

Types of Elf files

There are four types of elf types
Executable
It contains code and data that can be executed on a target operating system.
relocatable (.o files)
Created by compilers and assemblers, need to be processed by the linker before running. Relocatable (object) files can be considered as a foundation for creating executables and libraries.
shared object file
It contains information required the static and dynamic linking
core dump file
It is a file that contains the memeory image of the process that was terminated due to errors like memory address violation, illegal instruction, bus errors etc

All these elf types similar is their internal structure but serves purpose