# Working with symbols files

What is a symbols file?

File containing a table of the identifiers information relating to its declaration and location.


Compiling with or without debugging information for GDB

# gcc -o example_debug -ggdb example.c
# gcc -o example_nodebug example.c

Listing symbols from object file

# nm example_debug

Three columns: Virtual_address | Symbol_type | Symbol_name
Lowercase symbols types are local and uppercase are global (external).

Copying debug symbols to an external file

# objcopy --only-keep-debug example_debug example.dbg

Striping debug symbols added with -ggdb

# objcopy --strip-debug example_debug

Striping all symbols information unneeded

# objcopy --strip-debug --strip-unneeded example_debug

Adding debug symbols to a binary

# gdb example_nodebug
(gdb) symbol-file example.dbg

or

# objcopy --add-gnu-debuglink=example.dbg example_nodebug
# gdb example_nodebug

Debugging a core file

# gdb example corefile
(gdb) symbol-file example.dbg
(gdb) bt