GDB

Introduction

GDB is a powerful user-mode program debugging tool for UNIX and UNIX-like environments released by GNU. It is a mainstream tool for C/C++ program debugging.

Installing GDB

In CentOS, use Yum to install GDB.

yum install gdb   //CentOS

Usage

• Debug an application.

  gdb program

  

  program indicates the executable file to be debugged.

• Debug the core file of an application.

  gdb program core

  

  core indicates the file generated after a core dump occurs due to illegal program execution.

• Use GDB to debug a running program.

  gdb program $PID

  

  PID indicates the process ID of the program to be debugged.

• GDB debugging command

  (gdb) command *args

  

  (gdb) is displayed when accessing the GDB debugging page. command indicates the debugging command to be executed (some commands are abbreviated). *args indicates the parameters required by some debugging commands.

  Common parameters are as follows:

  Parameter	Description
  r	Runs the program until a breakpoint. The program stops running at the breakpoint and waits for the user to enter the next command.
  c	Resumes the program running until the next breakpoint.
  n	Traces the program in a single step. A function is directly called without stepping into the function body.
  s	Debugs the program. It steps into the function if a function is called.
  until	Runs the program until it exits the loop.
  finish	Runs the program until the current function returns.
  call	Calls a function that is visible in the program and passes parameters.
  l	Views the source code. list n is used to view the 10 lines before and after n. list func is used to view the function source code.
  b n	Adds a breakpoint at line n.
  b func	Sets a breakpoint at the beginning of the func() function.
  clear n	Clears the breakpoint in line n.