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| Chapter 13 PLVfile: Reading and Writing Operating System Files |

## 13.10 Tracing PLVfile Activity

PLVfile offers a standard PL/Vision toggle to allow you to dynamically turn on or off a trace of PLVfile activity. The triumvirate of programs for this toggle is:

>     PROCEDURE show;
>     PROCEDURE noshow;
>     FUNCTION showing;

When you call `PLVfile.show`, the trace is turned on (the default is that the trace is not active). Currently, PLVfile offers a trace of the `get_line` and `put_line` actions only.

It can be very frustrating to work with UTL_FILE and, by extension, PLVfile. You might think that you have taken all the necessary steps to perform file I/O, but you keep getting "Invalid Operation" errors. The PLVfile trace may well be able to give you the information you need to identify your problem more easily.

13.9 Handling File Errors with PLVfile |  | IV. Developer Utility Packages

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