The Executable and Linkable Format (ELF) is a common standard in computing for executables and object code. First published in the Tool Interface Standard and the System V Application Binary Interface, it was quickly accepted among different vendors of UNIX systems.
Today the ELF format has replaced the proprietary (or sometimes just platform-specific) and less extensible executable formats (primarily COFF) in the Linux, Solaris, Irix, and almost all modern BSD operating systems.
Other object code file formats are a.out and COFF; ELF could be considered a "competitor" to those, although it is generally considered to outperform both of them.
ELF file layout
Each ELF file is made up of one ELF header, followed by zero or more segments and zero or more sections. The segments contain information that is necessary for runtime execution of the file, while sections contain important data for linking and relocation. Each byte in the entire file is taken by no more than one section at a time, but there can be orphan bytes, which are not covered by a section. In the normal case of a UNIX executable one or more sections are enclosed in one segment. The segments and sections of the file are listed in a program header table and section header table respectively.
On many UNIX systems the command
man elf
may provide some more details.
Tools
readelf is a UNIX binary utility that displays information about one or more ELF files. A GPL implementation is provided by GNU Binutils
External links
Last updated: 08-23-2005 22:23:33
