The GNU Debugger, usually called just GDB, is the standard debugger for the GNU software system. It is a portable debugger which runs on many Unix-like systems and works for many programming languages, including C, C++, and FORTRAN. It is free software released under the GNU General Public License.
GDB offers extensive facilities for tracing and altering the execution of computer programs. The user can monitor and modify the values of programs' internal variables, and even call functions independently of the program's normal behavior.
The debugger does not contain its own graphical user interface, and defaults to a command-line interface. However, several front-ends have been built for it, such as DDD and the "GUD mode" in Emacs. These offer facilities similar to debuggers found in integrated development environments.
Some other debugging tools have been designed to work with GDB, such as memory leak detectors.
GDB target processors (as of 2003) include: