How to Use GDB

GDB, short for GNU debugger, is a powerful tool for debugging code. Here, our expert offers an introduction to its use.

Written by David Koff
Published on Mar. 09, 2023
Image: Shutterstock / Built In
Image: Shutterstock / Built In
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The GNU debugger, or GDB, is one of the most convenient debugging programs programmers and coders can use when testing code in various programming languages. The program lets programmers review different functions in coding production and can help debug programs with issues like logical errors, core dumps, and other common issues. GDB works with programs written in common programming languages.

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How to Use GDB for Debugging

Here’s a look at how programmers and enthusiasts can use GDB for debugging.

The first step is ensuring that GDB is installed on the computer. It can be installed to work on Linux, macOS (via Mac Ports), and Windows.

Once installed, users can go to the command prompt and type “gdb.” This will tell the host operating system that it can produce commands. Coders can then generate whatever code they require. Any script can be pasted into GDB to set up the data.

Next, programmers need only to enter a GDB executable command. For example, this line of code tells GDB to compile the script named “STL_vector_int_2.cpp” in C++ and to provide line-by-line information about how that script functions. 

Compile: g++ -g STL_vector_int_2.cpp

 

Common GDB Uses and Commands

In some situations, the code might require an input that determines where the program moves next. GDB can help programmers see how their coding works in situations where multiple outcomes are possible. 

The input should appear at a breakpoint or a point where the program stops. The programmer should be able to add new conditions to arrange how the program can work and if any further measures can work.

There are many commands in GDB. Some of the most common include:

Common GDB Commands

  • list: Lists the code.
  • r: Runs the program until a breakpoint or error.
  • b: Places a breakpoint. 
  • -g: Generates line-by-line information that a debugger can use again source code (this command is included in the line of code example above).
  • -o: Converts any GDB output into a file that can then be used in other software to help developers analyze content.
  • disable/enable: Lets a programmer start or stop individual breakpoints to allow the system to work as necessary.
  • -q: Quiet the startup message on GDB if necessary.
  • --args: Create new command-line arguments in the program with this command. New arguments can dispute possible results.
  • --pid: Sometimes an application might become stuck and unable to keep working. The --pid command lets the user review individual processes in the program and see what specific problems are causing loading delays.
  • nostop: GDB will not stop the program when it reaches a signal or other action. The debugging system will keep running the program, letting the programmer see if certain changes can impact the project in any form.
  • stop: The GDB setup will also stop the program when a signal appears as necessary. The program should announce when it stops.

The user can check the GDB program for details on other commands to apply and the best times to establish them.

 

Testing Content With GDB

The ./test command will let the programmer review the data in the program and how it might function. The process includes looking at how the program can work from start to finish and should give details on when it might stop or struggle to load. The command is mainly for reviewing the general work in the program, so more intensive testing is necessary when something wrong might happen.

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Start Using GDB

All programmers and coders need powerful tools to check their work. This is why debuggers are so popular in the coding community. GDB is one of the more powerful tools that programmers and coders can use to debug their work, find errors, and fix outcomes. GDB, like other debuggers, can help determine if code is working or if changes are necessary. GDB offers a variety of powerful commands and modifiers. As it works on every major OS, it’s a valuable tool for programmers or coders to keep in their toolbox.

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