[Linux system programming] 8.gdb debugging tool

Table of contents

basic instruction

-g

list

b

run or r

next or n

step or s

print or p

continue

quit

other instructions

finish

set args

info b

ptype

bt

frame

display

undisplay

process related

set trace child process

set trace parent process

Premise: The program must be written by yourself! ! !

gdb ./xxx.out

basic instruction

-g

Compile the executable file with this parameter to get the debug table.

list

List source code.

list 1

or

l 1

b

Set breakpoints.

b 行号
b 20	//在20行设置断点

 Set a conditional breakpoint.

b 行号 条件
b 20 if i=5

run or r

Run the program to find the location of the segment fault.

run

 or

r

 Set the parameters passed to the main function.

run 参数值
run abc 123

next or n

The next line of code skips the function.

next

 or

n

step or s

The next line of code, will enter the function.

step

or

s

print or p

View the value of a variable.

print 变量名
print i

 or

p 变量名
p i

continue

Continue to execute the code following the breakpoint.

quit

Exit gdb current debugging.

other instructions

finish

End the current function call.

finish

set args

Set the parameters passed to the main function.

set args 参数值
set args abc 123

info b

See the breakpoint information table.

info b

ptype

View variable types.

ptype 变量名
ptype i

bt

List the stack frames that exist in the current program, and you can view the stack frame number.

bt

frame

Switch stack frames.

frame 栈帧编号
frame 1

display

Set up tracking variables.

display 变量名
display i

undisplay

Unset the tracking variable.

undisplay 变量的编号
undisplay 2

process related

        When debugging with gdb, gdb can only track one process. Set the gdb debugging tool to track the parent process or track the child process through the command. By default the parent process is traced. It must be set before the fork function call to be valid.

set trace child process

set follow-fork-mode child

set trace parent process

set follow-fork-mode parent