> For the complete documentation index, see [llms.txt](https://xu-an.gitbook.io/sec/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://xu-an.gitbook.io/sec/how/gdb.md).

# GDB

gdb是一个由GNU开源组织发布的、UNIX/Linux操作系统下的、基于命令行的、功能强大的程序调试工具。

###  1、安装

在大多数Linux发行版中，gdb都是默认安装的，如果没有，那么在Ubuntu下可以通过apt-get进行安装，安装命令为： 

```
sudo apt-get install gdb 
```

如果需要调试其他架构的elf程序，则可以安装gdb-multiarch，安装命令为： 

```
sudo apt-get install gdb-multiarch 
```

此外，gdb也有很多插件，如peda、gef、pwndbg等，这里的插件提供了一些额外的命令，便于对程序进行逆向分析。这些插件都可以在Github上找到，根据其安装说明进行安装即可。下图为gdb安装了peda插件之后运行的界面，可以通过pedahelp命令查看新增的命令。

![](https://staticcdn1-5.umiwi.com/pcebook/online/img/202006/2415930024139100290345813196357108138602.jpg)

### 2、常用命令及功能

|                 命令                 |                                                                                     功能                                                                                    |
| :--------------------------------: | :-----------------------------------------------------------------------------------------------------------------------------------------------------------------------: |
|             gdb program            |                                                                              启动gdb开始调试program                                                                             |
|                quit                |                                                                                   退出调试器                                                                                   |
|            run arguments           |                                                                           运行被调试程序（指定参数arguments)                                                                          |
|          attach processID          |                                                                          把调试器附加到PID为processID的进程上                                                                         |
|           break \*address          |                                                                                    下断点                                                                                    |
|          info breakpoints          |                                                                                   查看所有断点                                                                                  |
|            delete number           |                                                                                   删除某个断点                                                                                  |
|                stepi               |                                                                              执行一条机器指令，单步进入子函数                                                                             |
|                nexti               |                                                                              执行一条机器指令，不会进入子函数                                                                             |
|              continue              |                                                                                    继续执行                                                                                   |
|       x/countFormatSize addr       | 以指定格式Format打印地址address处的指定大小size、指定数量count的对象Size:b (字节)、h (半字)、w (字)、g ( 8字节）Format： o (八进制)、d (十进制）、x (十六进制)、u (无符号十进制)、t (二进制)、）、f (浮 点数)、a (地址)、i (指令)、c (字符)、s (字符串） |
|            info register           |                                                                                   查看寄存器                                                                                   |
|              backtrace             |                                                                                 打印函数调用栈回溯                                                                                 |
|           set $reg=value           |                                                                                   修改寄存器                                                                                   |
|    set *(type*) (address)=value    |                                                                              修改内存地址addr为value                                                                             |
|            shell command           |                                                                              执行shell命令command                                                                             |
| set follow-fork-mode parent\|child |                                                                          当发生fork时，指示调试器跟踪父进程还是子进程                                                                         |
|       handler SIGALRM ignore       |                                                                   忽视信号SIGALRM，调试器接收到的SIGALRM信号不会发送给被调试程序                                                                  |
|        target remote ip:port       |                                                                                   连接远程调试                                                                                  |

end


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