常用命令
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gcc -g a.c
gdb a.out
- Type “help” followed by a class name for a list of commands in that class.
- Type “help all” for the list of all commands.
- Type “help” followed by command name for full documentation.
- Type “help info” followed by info subcommand name for full documentation.
- Type “apropos word” to search for commands related to “word”.
- Command name abbreviations are allowed if unambiguous.
——引用自 GDB 中的
h命令
| Shortest | Whole | Usage | Description | Example |
|---|---|---|---|---|
h |
help | help [all|CLASS|COMMAND]|[CLASS COMMAND] |
Print help. | h info b |
q |
quit | quit |
Exit gdb. | q |
l |
list | list [-][LINENUM|FILE:LINENUM|FUNCTION|FILE:FUNCTION|*ADDRESS] |
List specified function or line. | l main |
b |
break | break [PROBE_MODIFIER] [LOCATION] [thread THREADNUM] [if CONDITION] |
Set breakpoint at specified line or function. | b 1 |
wa |
watch | watch [-l|-location] EXPRESSION |
Set a watchpoint for an expression. | wa -l a |
disp |
display | display /FMT EXP |
Print value of expression EXP each time the program stops. | disp /3xb arr |
disa |
disable | disable [NUM]|[SUBCOMMAND [args...]] |
Disable some breakpoints. | disa 1 |
del |
delete | delete [NUM]|[SUBCOMMAND [args...]] |
Delete some breakpoints or auto-display expressions. | del 1 |
r |
run | run [args...] [<|>|>>] |
Start debugged program. | r arg1 arg2 |
bt |
backtrace | bt [full] [no-filters] [-][NUM] |
Print backtrace of all stack frames, or innermost COUNT frames. | bt f |
n |
next | next [N] |
Step program, proceeding through subroutine calls. | n 3 |
s |
step | step [N] |
Step program until it reaches a different source line. | s 3 |
c |
continue | continue [N] |
Continue program being debugged, after signal or breakpoint. | c 3 |
p |
print EXP |
Print value of expression EXP. | p main |
|
x |
examine | x/FMT ADDRESS |
Examine memory. | x/3xb a |
set |
set | set VAR=EXP|SUBCOMMAND |
With a subcommand, this command modifies parts of the gdb environment. | set var a=1 |
info |
info | info SUBCOMMAND |
Generic command for showing things about the program being debugged. | info b |
sho |
show | show [SUBCOMMAND args...] |
Generic command for showing things about the debugger. | sho |
fil |
file | file FILE |
Use FILE as program to be debugged. | fil a.out |
fin |
finish | finish |
Execute until selected stack frame returns. | fin |
unt |
until | same as break |
Execute until the program reaches a source line greater than the current or a specified location | unt 35 |
更多命令参见：gdb调试命令的使用及总结
使用技巧
进入 GDB 时不提示
在~/.bashrc中添加：alias gdb='gdb -q'
退出 GDB时不提示
在~/.gdbinit中添加：set confirm off
GDB中打印出链表的值
使用GDB的自定义函数功能:
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(gdb)help user-defined #显示自定义了哪些函数
(gdb)show user [command-name] #显示函数定义，若不指定名称，则全打印
(gdb)source file-name #从文件中导入命令
比如对于如下定义的C语言的单链表:
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typedef struct LNode{
ElemType data;
struct LNode *next;
}*Link, *Position, LNode;
可在~/.gdbinit中定义如下函数：
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#定义函数dump_list
define dump_list
set $_node = (Link)$arg0->next
set $i=1
while $_node
printf "%3d:%7s \n", $i++, $_node->data.xianshi
set $_node = $_node->next
end
end
#为函数dump_list加入文档说明
document dump_list
This is a command to dump all elements in Linked List
arg0 is the head
end
遇到过的问题
What does <value optimized out> mean in gdb?
It means you compiled with e.g.
gcc -O3and the gcc optimiser found that some of your variables were redundant in some way that allowed them to be optimised away. In this particular case you appear to have three variables a, b, c with the same value and presumably they can all be aliassed to a single variable. Compile with optimisation disabled, e.g.gcc -O0, if you want to see such variables (this is generally a good idea for debug builds in any case).
How to view a pointer like an array in GDB?
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p *array@len
*(T (*)[N])p
x/100w a
参见 c - How to view a pointer like an array in GDB? - Stack Overflow
给变量赋值？
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set var a=1
参见h set var