> For the complete documentation index, see [llms.txt](https://cajac.gitbook.io/ctf-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cajac.gitbook.io/ctf-notes/rev-eng/disassemblers/gdb.md).

# GDB

## Disassemble with GDB

To disassemble the `main` function with Intel-syntax using GDB by scripting with the `-ex` parameter

```bash
gdb -q -ex "set pagination off" -ex "set disassembly-flavor intel" -ex "disass main" -ex "quit" binary
```

## Usage information

<details>

<summary>gdb -h</summary>

```bash
┌──(kali㉿kali)-[~]
└─$ gdb -h       
This is the GNU debugger.  Usage:

    gdb [options] [executable-file [core-file or process-id]]
    gdb [options] --args executable-file [inferior-arguments ...]

Selection of debuggee and its files:

  --args             Arguments after executable-file are passed to inferior.
  --core=COREFILE    Analyze the core dump COREFILE.
  --exec=EXECFILE    Use EXECFILE as the executable.
  --pid=PID          Attach to running process PID.
  --directory=DIR    Search for source files in DIR.
  --se=FILE          Use FILE as symbol file and executable file.
  --symbols=SYMFILE  Read symbols from SYMFILE.
  --readnow          Fully read symbol files on first access.
  --readnever        Do not read symbol files.
  --write            Set writing into executable and core files.

Initial commands and command files:

  --command=FILE, -x Execute GDB commands from FILE.
  --init-command=FILE, -ix
                     Like -x but execute commands before loading inferior.
  --eval-command=COMMAND, -ex
                     Execute a single GDB command.
                     May be used multiple times and in conjunction
                     with --command.
  --init-eval-command=COMMAND, -iex
                     Like -ex but before loading inferior.
  --nh               Do not read ~/.gdbinit.
  --nx               Do not read any .gdbinit files in any directory.

Output and user interface control:

  --fullname         Output information used by emacs-GDB interface.
  --interpreter=INTERP
                     Select a specific interpreter / user interface.
  --tty=TTY          Use TTY for input/output by the program being debugged.
  -w                 Use the GUI interface.
  --nw               Do not use the GUI interface.
  --tui              Use a terminal user interface.
  -q, --quiet, --silent
                     Do not print version number on startup.

Operating modes:

  --batch            Exit after processing options.
  --batch-silent     Like --batch, but suppress all gdb stdout output.
  --return-child-result
                     GDB exit code will be the child's exit code.
  --configuration    Print details about GDB configuration and then exit.
  --help             Print this message and then exit.
  --version          Print version information and then exit.

Remote debugging options:

  -b BAUDRATE        Set serial port baud rate used for remote debugging.
  -l TIMEOUT         Set timeout in seconds for remote debugging.

Other options:

  --cd=DIR           Change current directory to DIR.
  --data-directory=DIR, -D
                     Set GDB's data-directory to DIR.

At startup, GDB reads the following early init files and executes their
commands:
   None found.

At startup, GDB reads the following init files and executes their commands:
   * system-wide init files: /etc/gdb/gdbinit
   * user-specific init file: /home/kali/.gdbinit

For more information, type "stream" from within GDB, or consult the
GDB manual (available as on-line info or a printed manual).

Report bugs to <https://www.gnu.org/software/gdb/bugs/>.

You can ask GDB-related questions on the GDB users mailing list
(gdb@sourceware.org) or on GDB's IRC channel (#gdb on Libera.Chat).

```

</details>

## Resources

GDB (The GNU Project Debugger) - Documentation: <https://sourceware.org/gdb/documentation/>

GDB (The GNU Project Debugger) - Homepage: <https://sourceware.org/gdb/>

Source and Machine Code - GDB Documentation: <https://sourceware.org/gdb/current/onlinedocs/gdb#Machine-Code>