Introduction to Debugging With GDB

The purpose of a debugger such as GDB is to allow you to see what is going on inside another program while it executes—or what another program was doing at the moment it crashed. As an initial introduction, see Installing GDB, GDB as Free software, Sample GDB Session, Getting In and Out of GDB, GDB Commands, Running Programs Under GDB and Getting help for GDB.

GDB can do four main kinds of things to help you catch bugs.

Start your program, specifying anything that might affect its behavior.
Make your program stop on specified conditions.
Examine what has happened, when your program has stopped.
Change things in your program, so you can experiment with correcting the effects of one bug and go on to learn about another.

For a more integral approach to debugging, see Stopping and Continuing your Program, Examining the Stack, Examining Source Files, Examining Data, Using GDB with Different Languages, Examining the Symbol Table, Altering Execution, GDB Files, Specifying a Debugging Target, Controlling GDB, Canned Sequences of Commands, Command Line Editing, Using History Interactively and Formatting Documentation.

You can use GDB to debug programs written in C or C++. For more information, see Switching between source languages, Setting the working language and “C and C++” in Supported languages.

Support for Modula-2 and Chill is partial. For information on Modula-2, see Modula-2. There is no further documentation on Chill yet. See also List of filename extensions and languages and Having GDB infer the source language.

Debugging Pascal, a program which use sets, subranges, file variables, or nested functions, does not currently work. GDB does not support entering expressions, printing values, or similar features using Pascal syntax.

GDB can be used to debug programs written in Fortran, although it does not yet support entering expressions, printing values, or similar features using Fortran syntax. It may be necessary to refer to some variables with a trailing underscore.

To report bugs, see Reporting Bugs in GDB.

For a brief history of the contributors to GDB, see Contributors to GDB.

To search for specific subjects, keyword references, or for general searches, see Index.