gdb

GDB, the GNU Debugger, is a portable debugger for many programming languages and targets. It is part of the GNU project and distributed under the GNU General Public License. GDB can debug programs locally or remotely, by launching a program under its control or by attaching to a running process, across a wide range of architectures and operating systems.

GDB provides breakpoints, including conditional and watchpoints, as well as stepping commands such as step, next, and finish. It can continue execution, handle signals, and inspect or modify program state. It offers examination of memory and registers, backtraces and stack frames, and disassembly. It supports expression evaluation and printing of complex values, and it can be extended with Python scripting for automation and custom commands. A text user interface is available, and many IDEs provide graphical front-ends that use GDB as the backend.

Language support covers C and C++, Fortran, and other languages; Go, D, Ada, Objective-C, Pascal, and Rust have varying levels of support. Debug information is typically provided by DWARF. For remote debugging, gdbserver can run on the target and GDB connects from the host.

Typical workflow: compile with debugging symbols (-g), avoid heavy optimization if precise debugging is needed, start GDB with the executable, set breakpoints, run, and inspect variables, memory, and call stacks. GDB is widely used in the GNU toolchain and interoperates with various development environments, making it a core tool for diagnosing and understanding program behavior on multiple platforms.