NET/MASTER Network Control Language (NCL) Programmer's Guide

9 Debugging an NCL Process
106160 Tandem Computers Incorporated 9–1
This section discusses how to debug an NCL process by using the NonStop
NET/MASTER Management Services (MS) DEBUG commands. These commands
assist you in detecting errors in logic and typography that prevent an NCL process
from executing correctly. DEBUG commands allow you to suspend execution of an
NCL process at any point and obtain a summary of information about it.
You normally use the DEBUG commands after locating and correcting all compilation
errors—when you discover an NCL process raises run-time errors or does not produce
the output you expect. Typically, you would issue DEBUG commands from the OCS
command input line and view the results in the OCS message display area.
This section discusses why you would use the DEBUG commands rather than another
debugging technique to debug an NCL process; lists suggested debugging guidelines;
shows how to define local equate commands and function keys that abbreviate
lengthy DEBUG commands; discusses how to use individual DEBUG commands;
and debugs an example NCL process from start to finish.
Table 9-1 summarizes the NonStop NET/MASTER MS DEBUG commands.
Table 9-1. Commands Used to Debug an NCL Process
Command Description
DEBUG BREAKPOINT Sets a breakpoint in an NCL process at the specified code position.
DEBUG CLEAR Clears one or more breakpoint(s) associated with an NCL process.
DEBUG DISPLAY Displays information about one or more variables in the currently
active set of variables.
DEBUG HOLD Suspends execution of the specified NCL process(es).
DEBUG LIST BREAKPOINTS Lists the breakpoints in an NCL process.
DEBUG LOAD Loads the specified file—an external NCL procedure or function—
before execution by an NCL process.
DEBUG LOG Starts the writing of debug messages to the activity log for the
specified NCL process(es).
DEBUG MODIFY Modifies the value of a variable in an NCL process.
DEBUG NOLOG Stops the writing of debug messages to the activity log for the
specified NCL process(es).
DEBUG RESUME Resumes execution of the currently suspended NCL process(es).
DEBUG SET Sets the current NCL process.
DEBUG SOURCE Displays the decompiled source statements of a suspended NCL
process.
DEBUG START Starts a single debug session.
DEBUG STEP Resumes execution of the specified NCL process by single or
multiple statements.
DEBUG STOP Stops a debug session.
DEBUG TRACE Obtains stack trace information from the targeted NCL process.