Question

Is there a way to test if a convenience variable has been set in gdb?

For example:

(gdb) if $_exitcode == 0
 >quit
 >end
Invalid type combination in equality test.
(gdb) p $_exitcode
$1 = void

$_exitcode is void because it is not set until the program terminates. The closest available construct is init-if-undefined, but this would require setting the variable to some sentinel value and testing against that.

Answer 1

Since normal process exit code is somewhere in between 0 and 255, I suggest following:

init-if-undefined $_exitcode = -1
if ($_exitcode != -1)
  quit
end