Miscellaneous tricks in gdb under Emacs

• To get back to debugging after a spate of editing, go to the gdb buffer (the one named *gud-<program name>*) and type up followed by down. This restores the source pointer in the other window.

• Reissuing the M-x gdb command to emacs will go to the pre-existing debugging session, if any. Therefore, after the program is recompiled, emacs's gdb buffer must be explicitly killed.

• To break when an input signal file is nonzero after a long string of zeros, use a conditional breakpoint. E.g.,

  cond 2 insamp != 0
  cont
  

• When single-stepping, everything on one line is executed by the next command. Thus, for example, typing n at the line

  for ( i=0; i<6; i++ ) { string[i] = 0 };
  

  will execute the entire loop, while

  for ( i=0; i<6; i++ ) { 
          string[i] = 0 
  };
  

  must be traversed all six iterations. (Of course, you can also set a breakpoint after the loop and then continue to it.)