ELF object files

ELF object files

This chapter describes the executable and linking format (ELF) of the object files produced by the C compilation system. The first section, ``Program linking'', focuses on how the format pertains to building programs. The second section, ``Program execution'', focuses on how the format pertains to loading programs. See ``Link editing'' for more information.

There are three main types of object files:

A relocatable file holds code and data suitable for linking with other object files to create an executable or a shared object file.
An executable file holds a program suitable for execution; the file specifies how exec() creates a program's process image.
A shared object file holds code and data suitable for linking in two contexts. First, the link editor processes the shared object file with other relocatable and shared object files to create another object file. Second, the dynamic linker combines it with an executable file and other shared objects to create a process image.

Programs manipulate object files with the functions contained in the ELF access library, libelf. See elf(S) for more information.