GDB Tutorial - A Walkthrough with Examples

GDB TutorialA Walkthrough with ExamplesCMSC 212 - Spring 2009Last modified March 22, 2009GDB TutorialWhat is gdb?“GNU Debugger”A debugger for several languages, including C and C++It allows you to inspect what the program is doing at a certainpoint during execution.Errors like segmentation faults may be easier to find with thehelp of gdb.http://sourceware.org/gdb/current/onlinedocs/gdb toc.html -online manualGDB TutorialAdditional step when compiling programNormally, you would compile a program like:gcc [flags] -o

For example:gcc -Wall -Werror -ansi -pedantic-errors prog1.c -o prog1.xNow you add a -g option to enable built-in debugging support(which gdb needs):gcc [other flags] -g -o

For example:gcc -Wall -Werror -ansi -pedantic-errors -g prog1.c -o prog1.xGDB TutorialStarting up gdbJust try “gdb” or “gdb prog1.x.” You’ll get a prompt that lookslike this:(gdb)If you didn’t specify a program to debug, you’ll have to load it innow:(gdb) file prog1.xHere, prog1.x is the program you want to load, and “file” is thecommand to load it.GDB TutorialBefore we go any furthergdb has an interactive shell, much like the one you use as soon asyou log into the linux grace machines. It can recall history with thearrow keys, auto-complete words (most of the time) with the TABkey, and has other nice features.TipIf you’re ever confused about a command or just want moreinformation, use the “help” ...