https://www.cnblogs.com/HKUI/p/8955443.html
然后使用run或者r命令开始程序的执行,也可以使用 run parameter将参数传递给该程序
参数列表
|
命令 |
命令缩写 |
命令说明 |
|
list |
l |
显示多行源代码 |
|
break |
b |
设置断点,程序运行到断点的位置会停下来 |
|
info |
i |
描述程序的状态 |
|
run |
r |
开始运行程序 |
|
display |
disp |
跟踪查看某个变量,每次停下来都显示它的值 |
|
step |
s |
执行下一条语句,如果该语句为函数调用,则进入函数执行其中的第一条语句 |
|
next |
n |
执行下一条语句,如果该语句为函数调用,不会进入函数内部执行(即不会一步步地调试函数内部语句) |
|
|
p |
打印内部变量值 |
|
continue |
c |
继续程序的运行,直到遇到下一个断点 |
|
set var name=v |
|
设置变量的值 |
|
start |
st |
开始执行程序,在main函数的第一条语句前面停下来 |
|
file |
|
装入需要调试的程序 |
|
kill |
k |
终止正在调试的程序 |
|
watch |
|
监视变量值的变化 |
|
backtrace |
bt |
产看函数调用信息(堆栈) |
|
frame |
f |
查看栈帧 |
|
quit |
q |
退出GDB环境 |
//e.c #includevoid debug( char * str) { printf( " debug info :%s\n " ,str ); } main( int argc, char * argv[]){ int i,j; j= 0 ; for(i= 0;i< 10;i++ ){ j+= 5 ; printf( " now a=%d\n " , j); } }
list 命令用法
list命令显示多行源代码,从上次的位置开始显示,默认情况下,一次显示10行,第一次使用时,从代码其实位置显示
gdb) list 1 #include2 void debug( char * str) 3 { 4 printf( " debug info :%s\n " ,str ); 5 } 6 main( int argc, char * argv[]){ 7 int i,j; 8 j= 0 ; 9 for(i= 0;i< 10;i++ ){ 10 j+= 5 ; (gdb)
list n显示已第n行未中心的10行代码
(gdb) list 8 3 { 4 printf("debug info :%s\n",str ); 5 } 6 main(int argc,char *argv[]){ 7 int i,j; 8 j=0; 9 for(i=0;i<10;i++){ 10 j+=5; 11 printf("now a=%d\n", j); 12 } (gdb)
list functionname显示以functionname的函数为中心的10行代码
(gdb) list main 1 #include2 void debug( char * str) 3 { 4 printf( " debug info :%s\n " ,str ); 5 } 6 main( int argc, char * argv[]){ 7 int i,j; 8 j= 0 ; 9 for(i= 0;i< 10;i++ ){ 10 j+= 5 ; (gdb)
list – 显示刚才打印过的源代码之前的代码
(gdb) list 10 5 } 6 main(int argc,char *argv[]){ 7 int i,j; 8 j=0; 9 for(i=0;i<10;i++){ 10 j+=5; 11 printf("now a=%d\n", j); 12 } 13 }(gdb) list - 1 #include2 void debug( char * str) 3 { 4 printf( " debug info :%s\n " ,str ); (gdb)
gdb) list 1 #include2 void debug( char * str) 3 { 4 printf( " debug info :%s\n " ,str ); 5 } 6 main( int argc, char * argv[]){ 7 int i,j; 8 j= 0 ; 9 for(i= 0;i< 10;i++ ){ 10 j+= 5 ; (gdb) 11 printf( " now a=%d\n " , j); 12 } 13 }(gdb) break 10 Breakpoint 1 at 0x40050a: file e.c, line 10 . (gdb) r Starting program: /mnt/hgfs/www/c/gcc/ e Breakpoint 1, main (argc= 1, argv= 0x7fffffffe548) at e.c: 10 10 j+= 5 ; (gdb) c Continuing. now a= 5 Breakpoint 1, main (argc= 1, argv= 0x7fffffffe548) at e.c: 10 10 j+= 5 ; (gdb) c Continuing. now a= 10 Breakpoint 1, main (argc= 1, argv= 0x7fffffffe548) at e.c: 10 10 j+= 5 ; (gdb)
使用delete breakpoints 断点号 删除断点
这里的断点号表示的是第几个断点,刚才执行break 10返回 reakpoint 1 at 0x40050a: file e.c, line 10.
中的1表示该断点的标号，因此使用 delete breakpoints 1表示删除第10行所定义的断点
clear n表示清除第n行的断点,因此clear 10等同于delete breakpoints 1
disable/enable n表示使得编号为n的断点暂时失效或有效
可使用info查看断点相关的信息
info breakpoints
gdb) info breakpoints No breakpoints or watchpoints. (gdb) break 10 Breakpoint 2 at 0x40050a: file e.c, line 10. (gdb) break 9 Breakpoint 3 at 0x: file e.c, line 9. (gdb) info breakpoints Num Type Disp Enb Address What 2 breakpoint keep y 0x000000000040050a in main at e.c:10 3 breakpoint keep y 0x0000000000 in main at e.c:9
display命令
查看参数的值
(gdb) break 10 Breakpoint 1 at 0x40050a: file e.c, line 10. (gdb) r Starting program: /mnt/hgfs/www/c/gcc/e Breakpoint 1, main (argc=1, argv=0x7fffffffe548) at e.c:10 10 j+=5; (gdb) display j 1: j = 0 (gdb) c Continuing. now a=5 Breakpoint 1, main (argc=1, argv=0x7fffffffe548) at e.c:10 10 j+=5; 1: j = 5 (gdb) display 1: j = 5 (gdb) display i 2: i = 1 (gdb) display j 3: j = 5 (gdb) display j*2 4: j*2 = 10 (gdb) info display Auto-display expressions now in effect: Num Enb Expression 4: y j*2 3: y j 2: y i 1: y j
也可以使用disable,enable,delete,info命令修改及查看其状态,用法与对断点的一样
step及next命令
step可使得程序逐条执行,即执行完一条语句然后在吓一跳语句前停下来,等待用户的命令
一般使用step命令是，可使用display或者watch命令查看变量的变化,从而判断程序行为是否符合要求
当下一条指令为函数时,s进入函数内部,在其第一条语句前停下来
step n,next n 表示连续但不执行n条指令,如果期间遇到断点,则停下来
(gdb) list 1 #include2 void debug( char * str) 3 { 4 printf( " debug info :%s\n " ,str ); 5 } 6 7 main( int argc, char * argv[]){ 8 int i,j; 9 j= 0 ; 10 for(i= 0;i< 10;i++ ){ (gdb) 11 j+= 5 ; 12 printf( " now j=%d\n " , j); 13 debug( " x=======x " ); 14 } 15 }(gdb) Line number 16 out of range; e.c has 15 lines. (gdb) break 11 Breakpoint 1 at 0x40050a: file e.c, line 11 . (gdb) r Starting program: /mnt/hgfs/www/c/gcc/ e1 Breakpoint 1, main (argc= 1, argv= 0x7fffffffe538) at e.c: 11 11 j+= 5 ; (gdb) s 12 printf( " now j=%d\n " , j); (gdb) s __printf (format= 0x400648 " now j=%d\n ") at printf.c: 30 30 { (gdb) bt # 0 __printf (format= 0x400648 " now j=%d\n ") at printf.c: 30 # 1 0x0000000000400525 in main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 (gdb) n 34 va_start (arg, format); (gdb) n 35 done = vfprintf (stdout, format, arg); (gdb) n now j= 5 39 } (gdb) bt # 0 __printf (format= out>) at printf.c: 39 # 1 0x0000000000400525 in main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 (gdb) n main (argc= 1, argv= 0x7fffffffe538) at e.c: 13 13 debug( " x=======x " ); (gdb) n debug info :x======= x 10 for(i= 0;i< 10;i++ ){ (gdb) s Breakpoint 1, main (argc= 1, argv= 0x7fffffffe538) at e.c: 11 11 j+= 5 ; (gdb) s 12 printf( " now j=%d\n " , j); (gdb) n now j= 10 13 debug( " x=======x " ); (gdb) n debug info :x======= x 10 for(i= 0;i< 10;i++ ){ (gdb)
watch
watch可设置观察点(watchpoint)。使用观察点可以使得当某表达式的值发生变化时,程序暂停执行。
执行该命令前，必须保证程序已经运行
(gdb) list 1 #include2 void debug( char * str) 3 { 4 printf( " debug info :%s\n " ,str ); 5 } 6 7 main( int argc, char * argv[]){ 8 int i,j; 9 j= 0 ; 10 for(i= 0;i< 10;i++ ){ (gdb) 11 j+= 5 ; 12 printf( " now j=%d\n " , j); 13 debug( " x=======x " ); 14 } 15 }(gdb) Line number 16 out of range; e.c has 15 lines. (gdb) b main Breakpoint 1 at 0x4004fa: file e.c, line 9 . (gdb) r Starting program: /mnt/hgfs/www/c/gcc/ e1 Breakpoint 1, main (argc= 1, argv= 0x7fffffffe538) at e.c: 9 9 j= 0 ; (gdb) watch j Hardware watchpoint 2 : j (gdb) c Continuing. Hardware watchpoint 2 : j Old value = 0 New value = 5 main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 12 printf( " now j=%d\n " , j); (gdb) c Continuing. now j= 5 debug info :x======= x Hardware watchpoint 2 : j Old value = 5 New value = 10 main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 12 printf( " now j=%d\n ", j);
print命令
(gdb) list 1 #include2 void debug( char * str) 3 { 4 printf( " debug info :%s\n " ,str ); 5 } 6 7 main( int argc, char * argv[]){ 8 int i,j; 9 j= 0 ; 10 for(i= 0;i< 10;i++ ){ (gdb) 11 j+= 5 ; 12 printf( " now j=%d\n " , j); 13 debug( " x=======x " ); 14 } 15 }(gdb) Line number 16 out of range; e.c has 15 lines. (gdb) break 12 Breakpoint 1 at 0x40050e: file e.c, line 12 . (gdb) r Starting program: /mnt/hgfs/www/c/gcc/ e1 Breakpoint 1, main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 12 printf( " now j=%d\n " , j); (gdb) p j $ 1 = 5 (gdb) c Continuing. now j= 5 debug info :x======= x Breakpoint 1, main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 12 printf( " now j=%d\n " , j); (gdb) p i,j $ 2 = 10 (gdb) p j $ 3 = 10 (gdb)
set var name=value
在程序运行中动态改变变量的值
(gdb) list 1 #include2 void debug( char * str) 3 { 4 printf( " debug info :%s\n " ,str ); 5 } 6 7 main( int argc, char * argv[]){ 8 int i,j; 9 j= 0 ; 10 for(i= 0;i< 10;i++ ){ (gdb) 11 j+= 5 ; 12 printf( " now j=%d\n " , j); 13 debug( " x=======x " ); 14 } 15 }(gdb) Line number 16 out of range; e.c has 15 lines. (gdb) break main Breakpoint 1 at 0x4004fa: file e.c, line 9 . (gdb) r Starting program: /mnt/hgfs/www/c/gcc/ e1 Breakpoint 1, main (argc= 1, argv= 0x7fffffffe538) at e.c: 9 9 j= 0 ; (gdb) watch i Hardware watchpoint 2 : i (gdb) watch j Hardware watchpoint 3 : j (gdb) c Continuing. Hardware watchpoint 3 : j Old value = 0 New value = 5 main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 12 printf( " now j=%d\n " , j); (gdb) c Continuing. now j= 5 debug info :x======= x Hardware watchpoint 2 : i Old value = 0 New value = 1 0x0000000000400533 in main (argc= 1, argv= 0x7fffffffe538) at e.c: 10 10 for(i= 0;i< 10;i++ ){ (gdb) c Continuing. Hardware watchpoint 3 : j Old value = 5 New value = 10 main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 12 printf( " now j=%d\n " , j); (gdb) c Continuing. now j= 10 debug info :x======= x Hardware watchpoint 2 : i Old value = 1 New value = 2 0x0000000000400533 in main (argc= 1, argv= 0x7fffffffe538) at e.c: 10 10 for(i= 0;i< 10;i++ ){ (gdb) c Continuing. Hardware watchpoint 3 : j Old value = 10 New value = 15 main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 12 printf( " now j=%d\n " , j); (gdb) c Continuing. now j= 15 debug info :x======= x Hardware watchpoint 2 : i Old value = 2 New value = 3 0x0000000000400533 in main (argc= 1, argv= 0x7fffffffe538) at e.c: 10 10 for(i= 0;i< 10;i++ ){ (gdb) c Continuing. Hardware watchpoint 3 : j Old value = 15 New value = 20 main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 12 printf( " now j=%d\n " , j); (gdb) c Continuing. now j= 20 debug info :x======= x Hardware watchpoint 2 : i Old value = 3 New value = 4 0x0000000000400533 in main (argc= 1, argv= 0x7fffffffe538) at e.c: 10 10 for(i= 0;i< 10;i++ ){ (gdb) set var i= 8 (gdb) c Continuing. Hardware watchpoint 3 : j Old value = 20 New value = 25 main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 12 printf( " now j=%d\n " , j); (gdb) c Continuing. now j= 25 debug info :x======= x Hardware watchpoint 2 : i Old value = 8 New value = 9 0x0000000000400533 in main (argc= 1, argv= 0x7fffffffe538) at e.c: 10 10 for(i= 0;i< 10;i++ ){ (gdb) c Continuing. Hardware watchpoint 3 : j Old value = 25 New value = 30 main (argc= 1, argv= 0x7fffffffe538) at e.c: 12 12 printf( " now j=%d\n " , j); (gdb) c Continuing. now j= 30 debug info :x======= x Hardware watchpoint 2 : i Old value = 9 New value = 10 0x0000000000400533 in main (argc= 1, argv= 0x7fffffffe538) at e.c: 10 10 for(i= 0;i< 10;i++ ){ (gdb) c Continuing. Watchpoint 2 deleted because the program has left the block in which its expression is valid. Watchpoint 3 deleted because the program has left the block in which its expression is valid. __libc_start_main (main= 0x4004eb , argc= 1, ubp_av= 0x7fffffffe538, init= out>, fini= out>, rtld_fini= out> , stack_end= 0x7fffffffe528) at libc-start.c: 258 258 exit (result); (gdb) c Continuing. Program exited with code 026.
(gdb) list 1 #include2 void debug( char * str) 3 { 4 printf( " debug info :%s\n " ,str ); 5 } 6 7 main( int argc, char * argv[]){ 8 int i,j; 9 j= 0 ; 10 for(i= 0;i< 10;i++ ){ (gdb) 11 j+= 5 ; 12 printf( " now j=%d\n " , j); 13 debug( " x=======x " ); 14 } 15 }(gdb) Line number 16 out of range; e.c has 15 lines. (gdb) b 13 Breakpoint 1 at 0x400525: file e.c, line 13 . (gdb) r Starting program: /mnt/hgfs/www/c/gcc/ e1 now j= 5 Breakpoint 1, main (argc= 1, argv= 0x7fffffffe538) at e.c: 13 13 debug( " x=======x " ); (gdb) s debug (str= 0x400652 " x=======x ") at e.c: 4 4 printf( " debug info :%s\n " ,str ); (gdb) bt # 0 debug (str= 0x400652 " x=======x ") at e.c: 4 # 1 0x000000000040052f in main (argc= 1, argv= 0x7fffffffe538) at e.c: 13 (gdb) s __printf (format= 0x400638 " debug info :%s\n ") at printf.c: 30 30 { (gdb) bt # 0 __printf (format= 0x400638 " debug info :%s\n ") at printf.c: 30 # 1 0x00000000004004e9 in debug (str= 0x400652 " x=======x ") at e.c: 4 # 2 0x000000000040052f in main (argc= 1, argv= 0x7fffffffe538) at e.c: 13 (gdb) s 34 va_start (arg, format); (gdb) bt # 0 __printf (format= 0x400638 " debug info :%s\n ") at printf.c: 34 # 1 0x00000000004004e9 in debug (str= 0x400652 " x=======x ") at e.c: 4 # 2 0x000000000040052f in main (argc= 1, argv= 0x7fffffffe538) at e.c: 13 (gdb) s 35 done = vfprintf (stdout, format, arg); (gdb) s _IO_vfprintf_internal (s= 0x333a58f040, format= 0x400638 " debug info :%s\n ", ap= 0x7fffffffe330) at vfprintf.c: 236 236 int save_errno = errno; (gdb) bt # 0 _IO_vfprintf_internal (s= 0x333a58f040, format= 0x400638 " debug info :%s\n ", ap= 0x7fffffffe330) at vfprintf.c: 236 # 1 0x000000333a24effa in __printf (format= out>) at printf.c: 35 # 2 0x00000000004004e9 in debug (str= 0x400652 " x=======x ") at e.c: 4 # 3 0x000000000040052f in main (argc= 1, argv= 0x7fffffffe538) at e.c: 13 (gdb) c Continuing. debug info :x======= x now j= 10 Breakpoint 1, main (argc= 1, argv= 0x7fffffffe538) at e.c: 13 13 debug( " x=======x " ); (gdb) bt # 0 main (argc= 1, argv= 0x7fffffffe538) at e.c: 13
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