There are two views for each of the three file types described in the previous section. These views support both the linking and execution of a program. The two views are summarized in Figure 2.5 where the view on the left of the figure is the link view and the view on the right of the figure is the execution view. The link view of the ELF object file is partitioned by sections and the execution view of the ELF object file is partitioned by segments. Thus, the programmer interested in obtaining section information about the program items such as symbol tables, relocation, specific executable code or dynamic linking information will use the link view; the programmer interested in obtaining segment information such as the location of the text segment or data segment will use the execution view. The ELF access library, libelf, provides a programmer with tools to extract and manipulate ELF object file contents for either view. The ELF header describes the layout of the rest of the object file. It provides information on where and how to access the other sections. The Section Header Table gives the location and description of the sections and is mostly used in linking. The Program Header Table provides the location and description of segments and is mostly used in creating a programs' process image. Both sections and segments hold the majority of data in an object file including: instructions, data, symbol table, relocation information, and dynamic linking information.
