The System Debug user interface is command oriented. That is, all requests for
System Debug to perform some operation must be expressed as commands. Normally,
commands are read either from the standard input device ($STDIN) in the
case of DAT, or from the session LDEV using low-level I/O routines in the
case of Debug. But commands may
also be read from command files, sometimes known as use
files, stored on disk.
System Debug output is displayed in one of two ways. List output is typically
written to the user's terminal as a sequence of lines, but may also be
automatically echoed
to disk files, interleaved with the interactive command input that
generated it. System Debug also offers a tiled window facility, which provides an interpretation of the machine state as well as code and data memory
areas. The windows are updated to reflect changes in the displayed areas
that occurred between commands.
This chapter discusses the various data types supported by System Debug
and how values of these types are created or accessed, manipulated,
and stored. Other topics, such as error handling, Control-Y
startup processing, error handling, Control-Y management, and
debugging at the console, are also discussed.
For detailed information of the syntax, operation, and output of individual
commands, please refer to chapter 4. Windows, and the commands that control
them, are explained in chapters 6 and 7.
