apt-get update

……

apt-get install  gdb

1 #include <stdio.h>

2

3

4 int main(void)

5 {

6         int a = 1;

7         int b = a;

8

9         printf("a = %d\tb =%d\n", a, b);

10        return 0;

[email protected]:~/LinuxC$ gcc -g main.c -o main

[email protected]

GNU gdb (GDB) 7.0.1-debian

Copyright (C) 2009 Free SoftwareFoundation, Inc.

License GPLv3+: GNU GPL version 3 or later<http://gnu.org/licenses/gpl.html>

This is free software: you are free tochange and redistribute it.

There is NO WARRANTY, to the extentpermitted by law.  Type "showcopying"

and "show warranty" for details.

This GDB was configured as"i486-linux-gnu".

For bug reporting instructions, please see:

<http://www.gnu.org/software/gdb/bugs/>...

Reading symbols from/home/lly7/LinuxC/main...done.

(gdb)start

Temporary breakpoint 1 at 0x80483cd: file main.c, line 6.

Starting program: /home/lly7/LinuxC/main

Temporary breakpoint 1, main () at main.c:6

6                int a = 1;

(gdb)start

Temporary breakpoint 1 at 0x80483cd: file main.c, line 6.

Starting program: /home/lly7/LinuxC/main

Temporary breakpoint 1, main () at main.c:6

6               int a = 1;

(gdb) n

7               int b = a;

(gdb) n

9               printf("a = %d\tb =%d\n", a, b);

(gdb) n

a =1   b = 1

10              return 0;

(gdb) quit

Adebugging session is active.

         Inferior 1 [process 6268] will bekilled.

Quitanyway? (y or n) y

[email protected]:~/LinuxC$ gdb main

……

(gdb) start

……

(gdb) b 9

Breakpoint 2 at 0x80483dd: file main.c,line 9.

(gdb) c

Continuing.

Breakpoint 2, main () at main.c:9

9                printf("a= %d\tb = %d\n", a, b);

(gdb) display b

1: b = 1

(gdb) n

a = 1        b= 1

10              return0;

1: b = 1

(gdb)

11     }

1: b = 1

(gdb)

0xb7ea5ca6 in __libc_start_main () from/lib/i686/cmov/libc.so.6

(gdb)

Single stepping until exit from function__libc_start_main,

which has no line number information.

Program exited normally.

(gdb) quit

(gdb) b 8

Breakpoint 2 at 0x80483dd: file main.c, line 8.

(gdb) b 9

Note: breakpoint 2 also set at pc 0x80483dd.

Breakpoint 3 at 0x80483dd: file main.c, line 9.

(gdb) i breakpoints

Num    Type           Disp EnbAddress    What

2      breakpoint     keep y   0x080483dd in main at main.c:8

3      breakpoint     keep y   0x080483dd in main at main.c:9

(gdb) delete 3

(gdb) i breakpoints

Num     Type           Disp Enb Address    What

(gdb) b 9 if a == 2

Breakpoint 6 at0x80483dd: file main.c, line 9.

(gdb) i breakpoints

Num     Type           Disp Enb Address    What

6       breakpoint     keep y  0x080483dd in main at main.c:9

         stop only if a == 2

(gdb) r

The program beingdebugged has been started already.

Start it from thebeginning? (y or n) y

Starting program:/home/lly7/LinuxC/main

a = 1          b = 1

Program exitednormally.

(gdb) start

……

(gdb) watch  b

Hardware  watch point 8: b

(gdb) c

Continuing.

Hardwarewatchpoint 8: b

Old value =-1208147980

命令

描述

backtrace(bt)

檢視各級函式呼叫及引數

finish

連續執行到當前函式返回為止，然後停下來等待命令

frame(f)  幀編號

選擇棧幀

info(i)  locals

檢視當前棧幀區域性變數的值

list(l)

列出原始碼，接著上次的位置往下列，每次列十行

list  行號

列出第幾行開始的原始碼

list  函式名

列出某個函式的原始碼

next(n)

執行下一行語句

print(p)

打印表達式的值，通過表示式的值可以修改變數的值或者呼叫函式

quit(q)

退出gdb除錯環境

set  var

修改變數的值

start

開始執行程式，停在main函式第一行語句前面等待命令

step(s)

執行下一行語句，如果有函式則進入到函式中

break(b)  行號

在某一行設定斷點

break   函式名

在某個函式開頭設定斷點

break… if…

設定條件斷點

continue(c)

從當前位置開始連續執行程式

delete breakpoints 斷點號

刪掉此號的斷點

display  變數名

跟蹤檢視某個變數，每次停下來都顯示它的值

disable  breakpoints 斷點號

禁用此斷點

enable  斷點號

啟用此斷點

info(i)  breakpoints

檢視當前設定了哪些斷點

run(r)

從頭開始連續執行程式

undisplay  跟蹤顯示行號

取消跟蹤顯示

watch

設定觀察點

info(i)   watchpoints

檢視當前設定了哪些觀察點

x

從某個位置開始列印儲存單元的內容，全部當成位元組來看，而不區分哪個位元組屬於哪個變數

disassemble

反彙編當前函式或者指定的函式，單獨用disassemble命令是反彙編當前函式，如果disassemble命令後面跟函式名或地址則反彙編指定的函式。

si

可以一條指令一條指令地單步除錯。

info  registers

可以顯示所有暫存器的當前值。在gdb中表示暫存器名時前面要加個$，例如p $esp可以列印esp暫存器的值。