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【Linux】GDB调试教程（新手小白）

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【Linux】GDB调试教程（新手小白）

2023-12-05 16:16| 来源: 网络整理| 查看: 265

目录

1. GDB简介

2. GDB安装教程

1）检查机器上是否安装gdb

2) 下载gdb源码包

3) 解压gdb源码包

4) 安装

5) 检查是否安装成功

3. GDB入门操作

1）创建测试代码

2）启动gdb

3）断点

4）运行

5）打印变量的的值

6）退出gdb

参考文章

 

1. GDB简介

GDB，全称 GNU symbolic debugger，简称 GDB调试器，是 Linux 平台下最常用的一款程序调试器

2. GDB安装教程

CentOSx下安装GDB

1）检查机器上是否安装gdb

rpm -qa | grep gdb

[root@]# rpm -qa | grep gdb gdbm-1.10-8.el7.x86_64 gdbm-devel-1.10-8.el7.x86_64

若安装，则采用以下命令卸载

rpm -e --nodeps [软件版本]

[root@]# rpm -e --nodeps gdbm-1.10-8.el7.x86_64 [root@]# rpm -e --nodeps gdbm-devel-1.10-8.el7.x86_64 2) 下载gdb源码包

wget http://mirrors.ustc.edu.cn/gnu/gdb/gdb-7.9.1.tar.xz

[root@]# wget http://mirrors.ustc.edu.cn/gnu/gdb/gdb-7.9.1.tar.xz --2020-10-19 15:05:39-- http://mirrors.ustc.edu.cn/gnu/gdb/gdb-7.9.1.tar.xz Resolving mirrors.ustc.edu.cn (mirrors.ustc.edu.cn)... 202.141.176.110, 218.104.71.170, 2001:da8:d800:95::110 Connecting to mirrors.ustc.edu.cn (mirrors.ustc.edu.cn)|202.141.176.110|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 17867692 (17M) [application/octet-stream] Saving to: ‘gdb-7.9.1.tar.xz’ 100%[====================================================================================================================================================>] 17,867,692 36.5MB/s in 0.5s 2020-10-19 15:05:39 (36.5 MB/s) - ‘gdb-7.9.1.tar.xz’ saved [17867692/17867692] 3) 解压gdb源码包

tar -xf gdb-7.9.1.tar.xz

[root@]# tar -xf gdb-7.9.1.tar.xz 4) 安装

cd gdb-7.9.1

sudo yum install texinfo

./configure

make

sudo make install

[root@]# cd gdb-7.9.1 [root@]# sudo yum install texinfo . . . Dependency Installed: perl-Text-Unidecode.noarch 0:0.04-20.el7 perl-libintl.x86_64 0:1.20-12.el7 Complete! [root@]# ./configure . . . configure: creating ./config.status config.status: creating Makefile [root@]# make . . . make[1]: Nothing to be done for `all-target'. make[1]: Leaving directory `/root/.vimplus/gdb-7.9.1' [root@]# make install . . . make[1]: Nothing to be done for `install-target'. make[1]: Leaving directory `/root/.vimplus/gdb-7.9.1' 5) 检查是否安装成功

gdb -v

[root@]# gdb -v GNU gdb (GDB) 7.9.1 Copyright (C) 2015 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-unknown-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: . Find the GDB manual and other documentation resources online at: . For help, type "help". Type "apropos word" to search for commands related to "word". 3. GDB入门操作 命令 简写形式 说明 backtrace bt、where 显示backtrace break b 设置断点 continue c、cont 继续执行 delete d 删除断点 finish 运行到函数结束 info breakpoints 显示断点信息 next n 执行下一行 print p 显示表达式 run r 运行程序 step s 一次执行一行，包括函数内部 x 显示内存内容 until u 执行到指定行 其他命令 directory dir 插入目录 disable dis 禁用断点 down do 在当前调用的栈帧中选择要显示的栈帧 edit e 编辑文件或者函数 frame f 选择要显示的栈帧 forward-search fo 向前搜索 generate-core-file gcore 生成内核转存储 help h 显示帮助一览 info i 显示信息 list l 显示函数或行 nexti ni 执行下一行(以汇编代码为单位) print-object po 显示目标信息 sharelibrary share 加载共享的符号 stepi si 执行下一行 1）创建测试代码

vim test.c

gcc -g -o test.exe test.c

关于vim/vi的用法这里不再概述，推荐vim的配置程序vimplus

写完代码后，gcc编译代码（PS. 如果gcc编译的时候没有加上-g参数，那么就不会保留调试参数，就不能用gdb调试）

测试代码如下：

#include #include int main( int argc , char *argv[] ) { int a = 1; int i = 0; int b[3] = {0,1,2}; for(i = 0; i < 3;i++) b[i] = b[i] + 1; printf("%d\n",a); int *p; p = b; printf("%d\n",p[0]); return 0; } 2）启动gdb

       在 Linux 操作系统中，当程序执行发生异常崩溃时，系统可以将发生崩溃时的内存数据、调用堆栈情况等信息自动记录下载，并存储到一个文件中，该文件通常称为 core 文件，Linux 系统所具备的这种功能又称为核心转储（core dump）。幸运的是，GDB 对 core 文件的分析和调试提供有非常强大的功能支持，当程序发生异常崩溃时，通过 GDB 调试产生的 core 文件，往往可以更快速的解决问题。

查看是否开启 core dump 这一功能

ulimit -a

[root@]# ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 7284 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 65535 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 7284 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited

如果 core file size（core 文件大小）对应的值为 0，表示当前系统未开启 core dump 功能

开启 core dump

ulimit -c unlimited

[root@]# ulimit -c unlimited [root@]# ulimit -a core file size (blocks, -c) unlimited data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 7284 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 65535 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 7284 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited

unlimited 表示不限制 core 文件的大小

测试代码：

1 #include 2 3 int main() 4 { 5 char *p = NULL; 6 *p = 123; 7 return 0; 8 }

测试结果：

[root@]# vim main.c [root@]# gcc -g -o main.exe main.c [root@]# ls main.c main.exe test.c test.exe [root@]# ./main.exe Segmentation fault (core dumped) [root@]# ls core.17313 main.c main.exe test.c test.exe

测试代码中，发生内存访问错误，程序崩溃，崩溃信息存入core.17313文件中

启动gdb

gdb test.exe

[root@]# gdb test.exe GNU gdb (GDB) 7.9.1 Copyright (C) 2015 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-unknown-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: . Find the GDB manual and other documentation resources online at: . For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from test.exe...done. (gdb)_ 3）断点

根据行号设置断点

第一种  (gdb) b 5 

第二种  (gdb) b test.c:5

根据函数设置断点

(gdb) b main

根据条件设置断点

(gdb) b test.c:10 if a == 1

根据偏移量设置断点

(gdb) b +12

根据地址设置断点

(gdb) b *0x40059b

设置临时断点

临时断点只生效一次

(gdb) tbreak test.c:12

(gdb) b test.c:5 Breakpoint 1 at 0x40053c: file test.c, line 5. (gdb) b main Note: breakpoint 1 also set at pc 0x40053c. Breakpoint 2 at 0x40053c: file test.c, line 6. (gdb) b test.c:10 if a == 1 Breakpoint 3 at 0x400568: file test.c, line 10. (gdb) b +12 Breakpoint 4 at 0x40059b: file test.c, line 13. (gdb) b *0x40059b Note: breakpoint 4 also set at pc 0x40059b. Breakpoint 5 at 0x40059b: file test.c, line 13. (gdb) tbreak test.c:12 Note: breakpoints 4 and 5 also set at pc 0x40059b. Temporary breakpoint 6 at 0x40059b: file test.c, line 12.

显示所有断点

(gdb) info break

(gdb) info break Num Type Disp Enb Address What 1 breakpoint keep y 0x000000000040053c in main at test.c:5 2 breakpoint keep y 0x000000000040053c in main at test.c:6 3 breakpoint keep y 0x0000000000400568 in main at test.c:10 stop only if a == 1 4 breakpoint keep y 0x000000000040059b in main at test.c:13 5 breakpoint keep y 0x000000000040059b in main at test.c:13 6 breakpoint del y 0x000000000040059b in main at test.c:12

清除断点

清除某个断点 (gdb) delete 4

清除所有断点 (gdb) delete 

(gdb) delete 4 (gdb) delete Delete all breakpoints? (y or n) y (gdb) info break No breakpoints or watchpoints.

清除当前行断点  (gdb) clear

Breakpoint 3, main (argc=1, argv=0x7fffffffe508) at test.c:13 13 p = b; (gdb) clear Deleted breakpoint 3 4）运行 运行和继续

运行 r

继续单步调试 n

继续执行到下一个断点 c

查看源码和行号

l

(gdb) l 1 #include 2 #include 3 4 int main( int argc, char *argv[]) 5 { 6 int a = 1; 7 int i = 0; 8 int b[3] = {0, 1, 2}; 9 for (i = 0; i < 3; i++) 10 b[i] = b[i] + 1; (gdb) l 11 printf("%d\n", a); 12 int *p; 13 p = b; 14 printf("%d\n", p[0]); 15 return 0; 16 } (gdb) l Line number 17 out of range; test.c has 16 lines. 5）打印变量的的值 打印变量

p a

打印指针

p p

打印main函数中的变量a

p 'main'::a

打印指针指向的内容，@后面跟的是打印的长度

p *p@3

(gdb) run Starting program: /root/daizhh/test.exe Breakpoint 1, main (argc=1, argv=0x7fffffffe508) at test.c:11 11 printf("%d\n", a); (gdb) p a $1 = 1 (gdb) p b $2 = {1, 2, 3} (gdb) n 1 13 p = b; (gdb) c Continuing. Breakpoint 2, main (argc=1, argv=0x7fffffffe508) at test.c:14 14 printf("%d\n", p[0]); (gdb) p p $3 = (int *) 0x7fffffffe400 (gdb) p 'main'::a $4 = 1 (gdb) p *p@3 $5 = {1, 2, 3} 设置变量打印

set $index = 0

p p[$index]

(gdb) set $index = 0 (gdb) p p[$index] $6 = 1 设置打印格式 x 按十六进制格式显示变量d 按十进制格式显示变量u 按十六进制格式显示无符号整型o 按八进制格式显示变量t 按二进制格式显示变量a 按十六进制格式显示变量c 按字符格式显示变量f 按浮点数格式显示变量

(gdb) p/x a（按十六进制格式显示变量）

(gdb) p/x a $7 = 0x1 6）退出gdb

q

参考文章

http://c.biancheng.net/gdb/

https://blog.csdn.net/wh_computers/article/details/94618240

https://blog.csdn.net/andrewgithub/article/details/88210949



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