How to execute finish and then another command from inside commands?

Question

This is a reduced example of the structure of my code:

void increment(int j);

int main()
{
  int i = 0;

  while(1) {
    i = increment(i);
  }

  return 0;         


        

Answer 1

The problem is that finish seems to stop abort the commands set for the first breakpoint after it.

This is expected behavior: any command that resumes the inferior (being debugged) process (as finish does) also stops the execution of canned command sequence.

Update:

See also this GDB bug report.

Is there a way to tell GDB to print i right after any increment call?

Yes:

1. Diassemble increment routine using disas command. Find ret instruction at the end of it (there will only be one).
2. Set a breakpoint on that instruction, using break *0xNNNNN syntax.

3. Attach a command to that breakpoint:

   command N
    print $rax    # or $eax if you are on 32-bit x86 platform
    continue
   end
   

Voila: you should get values being returned from increment() printed (just before being returned).