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Tools for Manipulating Object Files

There are a number of tools available on Linux systems to help you understand and manipulate object files. In particular, the GNU binutils package is especially helpful and runs on every Linux platform.

ar

Creates static libraries, and inserts, deletes, lists, and extracts members.

  • c Create the archive.
  • t List the files in the archive.
  • r Replace or add the specified files to the archive.
  • d Delete the specified archive files.
  • x Extract the specified archive members into the files named by the command line arguments. If no members are specified, all the members of the archive are extracted into the current directory.
  • s Running ar s on an archive is equivalent to running ranlib on it. 
arc rcs libvec.a addvec.o multvec.o

strings

Lists all of the printable strings contained in an object file.

$ strings main.o

strip

Deletes symbol table information from an object file.

$ strip main.o

nm

Lists the symbols defined in the symbol table of an object file.

$ nm main.o

size

Lists the names and sizes of the sections in an object file.

$ size multvec.o

readelf

Displays the complete structure of an object file, including all of the information encoded in the ELF header. Subsumes the functionality of size and nm.

Check ELF header by typing:

readelf -h kernel

Check program headers by typing:

readelf -l kernel

Check section headers by typing:

readelf -S kernel

objdump

The mother of all binary tools.Can display all of the informationinan object file. Its most useful function is disassembling the binary instructions in the '.text' section.

Examine the full list of the names, sizes, and link addresses of all the sections in the kernel executable by typing:

objdump -h obj/kern/kernel

Inspect the program headers by typing:

objdump -x obj/kern/kernel

You can see the entry point by typing:

objdump -f obj/kern/kernel

You can read symbol table by typing:

objdump -G obj/kern/kernel

Disassemble object file

objdump -d obj/kern/kernel

ldd

Lists the shared libraries that an executable needs at run time. 

ldd prog

addr2line

convert addresses into file names and line numbers.

$ addr2line -e kernel/kernel 0000000080002de2