readelf is a program for displaying various information about

object file An object file is a file that contains machine code or bytecode, as well as other data and metadata, generated by a compiler or assembler from source code during the compilation or assembly process. The machine code that is generated is kno ...

s on

Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

-like systems, similar to

objdump objdump is a command-line program for displaying various information about object files on Unix-like operating systems. For instance, it can be used as a disassembler to view an executable in assembly form. It is part of the GNU Binutils for fi ...

. It is part of the

GNU binutils The GNU Binary Utilities, or , is a collection of programming tools maintained by the GNU Project for working with executable code including assembly, linking and many other development operations. The tools are originally from Cygnus Solut ...

readelf and objdump

Both programs are capable of displaying the contents of

ELF An elf (: elves) is a type of humanoid supernatural being in Germanic peoples, Germanic folklore. Elves appear especially in Norse mythology, North Germanic mythology, being mentioned in the Icelandic ''Poetic Edda'' and the ''Prose Edda'' ...

format files. objdump sees an ELF file through a BFD filter. If BFD has a bug where it disagrees about a machine constant in e_flags, then the odds are good that it will remain internally consistent. The linker sees it the BFD way, objdump sees it the BFD way, GAS sees it the BFD way. There was need for a tool to go find out what the file actually says. This is why the readelf program does not link against the BFD library - it exists as an independent program to help verify the correct working of BFD. There is also the case that readelf can provide more information about an ELF file than is provided by

. In particular it can display DWARF debugging information which (at the moment) objdump cannot.

Example

The following command displays the contents of the file's dynamic section (to examine the

shared library In computing, a library is a collection of System resource, resources that can be leveraged during software development to implement a computer program. Commonly, a library consists of executable code such as compiled function (computer scienc ...

dependencies and

rpath In computer science, rpath designates the run-time search path hard-coded in an executable file or library. Dynamic linking loaders use the rpath to find required libraries. Specifically, it encodes a path to shared libraries into the header ...

): $ readelf -d

References

Unix programming tools GNU Project software {{unix-stub