类Unix系统中调试工具gdb介绍

gdb调试：
  进入调试
  gcc -o xxx.o xxx.c -g   
  gdb xxx.o   
  显示源代码
  (gdb) l  
  在第六行打上断点
  (gdb) b 6
查看断点号
(gdb) info b
删除断点号为3的断点
(gdb) d 3

Breakpoint 1 at 0x80483e7: file a.c, line 6.
  运行代码
   (gdb) r
Starting program: /home/xyw/study/3th/a.o 

Breakpoint 1, main () at a.c:6
6        printf("dasdajhmdfh");
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.80.el6.i686

    继续往下执行
(gdb) c
Continuing.
    进入函数，分布执行每条代码。
    (gdb) s
 打印变量fd的值
(gdb) p fd

Breakpoint 3, main () at a.c:9
     不进入函数，执行代码
    (gdb) n

Breakpoint 4, main () at a.c:10
    帮助命令
    (gdb) h
List of classes of commands:

aliases -- Aliases of other commands
breakpoints -- Making program stop at certain points
data -- Examining data
files -- Specifying and examining files
internals -- Maintenance commands
obscure -- Obscure features
running -- Running the program
stack -- Examining the stack
status -- Status inquiries
support -- Support facilities
tracepoints -- Tracing of program execution without stopping the program
user-defined -- User-defined commands
    退出调试
    (gdb) q
A debugging session is active.

    Inferior 1 [process 5171] will be killed.

Quit anyway? (y or n) y