Debug Tutorial: How to Control Execution

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cont [ context ]
run [ prog_args ] [ < input_file ] [ > output_file ]
wait [ context ]
next [ context ] [ count ]
nexti [ context ] [ count ]
step [ context ] [ count ]
stepi [ context ] [ count ]

Program execution is controlled by first setting breakpoints and/or watchpoints and then running the application until one of them is encountered. Alternatively, execution can be stepped along one source line (or one instruction) at a time.

• cont command resumes execution from the current location.

• run command (re)starts execution at the beginning of the program. Application arguments and I/O redirection of the preceding load or run command are reused unless specified. Breakpoints, watchpoints and tracepoints are preserved.

• wait must be used with cont and run to allow terminal I/O to occur while the program is executing. The debugger prompt will not appear until all processes in the context have reached a stopped state. During this time, any keyboard input will be consumed by the application and output from the application is printed to the screen immediately.

• If wait is not used, application output is only printed to the screen between execution of debugger commands. In this case, hitting the Return key several times will cause the buffered application output to be displayed to the screen.

• Use <Ctrl-C> to interrupt a debug command such as wait.
  Note: <Ctrl-C> DOES NOT STOP PROGRAM EXECUTION!!

• Use the halt command to interrupt program execution.
  Note: halt DOES STOP PROGRAM EXECUTION!!

• next causes a single source line to be executed. A procedure call will be treated as a single source line, thus stepping over any procedures.

• step acts the same as next except that procedures are stepped into and executed line by line. A procedure which does not contain line number information is treated as a single source line and stepped over.

• stepi and nexti cause a single instruction to be executed.

• Use count with any of the next and step commands to execute multiple lines.

Examples:

(all) > cont;wait
Hello has started on 0
Hello has started on 1
Hello has started on 2
Hello has started on 3
Hello has started on 4
Hello has started on 5
        Context             State      Reason    Location     Procedure
  ====================== ============ ========= ========== ====================
>*(all)                  Breakpoint   C Bp1     Line 22    main()
(all) > step(0)
        Context             State      Reason    Location     Procedure
  ====================== ============ ========= ========== ====================
>*(0)                    Stepped                Line 5     one()
(all) > next(2,3)
        Context             State      Reason    Location     Procedure
  ====================== ============ ========= ========== ====================
>*(2,3)                  Stepped                Line 24    main()
(all) > run;wait
/cougar/bin/yod: Received SIGINT (2)
 *** initializing Debug for parallel application...
Hello has started on 0
Hello has started on 1
Hello has started on 2
Hello has started on 3
Hello has started on 4
Hello has started on 5
        Context             State      Reason    Location     Procedure
  ====================== ============ ========= ========== ====================
>*(all)                  Breakpoint   C Bp1     Line 22    main()