Debugging tool for Linux - gdb (super detailed)

1. Background

• There are two ways to release a program, debug mode and release mode.
• Binary programs produced by Linux gcc/g++ are in release mode by default.
• To use gdb for debugging, you must add the -g option when generating a binary program from the source code and publish it in debug mode.
  

2. Get started

The use of instructions is demonstrated with the following simple small code in C language:

  1 #include <stdio.h>
  2 
  3 int SumAdd(int x)
  4 {
    
    
  5     int i=1;
  6     int sum=0;
  7     for(i=1;i<=x;i++)
  8     {
    
    
  9         sum+=i;
 10     }
 11     return sum;
 12 }
 13 
 14 int main()
 15 {
    
    
 16     printf("%d \n",SumAdd(100));
 17     return 0;
 18 }            

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1. list or l line number: display the file source code, and then go down from the last position, 10 lines at a time.

例：l 0

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2. list or l function name: List the source code of a function.

例：l SumAdd

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3. r or run: run the program.

Note: If there is no breakpoint, the program will run to the end

例：r

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4. break or b line number: set a breakpoint on a certain line

例：b 3

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5. n or next: single execution (similar to F10 in vs)

Note: Single execution needs to be carried out when debugging is started. You need to break the point first, and then execute r to the breakpoint position.

例：n

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6. s or step: Enter function call (similar to F11 in vs)

例：s

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7. break function name: Set a breakpoint at the beginning of a function

例：break SumAdd

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8. info break or info b: View breakpoint information.

例：info b

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9. finish: Execute until the current function returns, then wait for the command

例：finish

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10. p variable: print variable value.

例：p sum

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11. continue or c: execute the program continuously rather than single-step from the current position

例：c

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12. run or r: execute the program continuously from the beginning instead of single step

r

13. delete breakpoints: delete all breakpoints

例；delete breakpoints

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14. delete breakpoints n: Delete the breakpoint with serial number n

delete breakpoints 5

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15. disable breakpoints: disable breakpoints

例：disable breakpoints

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16. enable breakpoints: enable breakpoints

例：enable breakpoints

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17. Display variable name: Track and view a variable, and display its value every time you stop.

例：display sum

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18. undisplay: Cancel tracking of previously set variables

例：undisplay

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19. until X (line number): jump to line X

例：until 11

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20. breaktrace or bt: View function calls and parameters at all levels

例：bt

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21. q or quit: exit gdb

例：q

(End of chapter)