First six debugger commands s - single-step execute the next line, stepping into subroutines. n - single-step execute the next line, stepping over subroutines. l <line-number, range, or subroutine> - list source-code. x <expression> - evaluate and pretty-print <expression> r - non-stop execute until the return from the current subroutine <any perl code> - run this perl code (including code that modifies the running program) (see example)