Copyright 1992-2016 by Kevin G. Barkes

All rights reserved. This article may be duplicated or
redistributed provided no alterations of any kind are
made to this file.

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DCL DIALOGUE

Originally published February, 1992

Stupid DCL Tricks Revisited

By Kevin G. Barkes

As a rule, I try to separate "Stupid DCL" columns by
at least four months or so. That the topic reappears
so soon after the last installment (December, 1991) can
be blamed on the recent traumatic move my family made
to a new house.

I won't talk about how hard it is for a self-employed
independent consultant to get a mortgage these days.
(Where's Neil Bush when you need him?) I also won't bring up
the fact it cost 50% more to have my eight phone lines
installed than it did to have a moving company transfer the
equivalent of ten rooms of furnishings to our new location.

I won't bore you with the details of how the telephone
company managed to effectively short out all of the phones
in the neighborhood for two days while doing the
installation, or how they destroyed my next door neighbor's
15-year-old rhododendron bush while putting in the new
underground cable. Nothing like memorable first
impressions...

And I won't even consider begging for your sympathy by
noting all of my DCL files and documentation are buried
somewhere in the midst of 50 sealed cartons in the garage.

Instead, I will maintain my normally cheerful demeanor
and plunge ahead with another thrilling chapter of Stupid
DCL Tricks, or Things Which Come To Mind After Dropping
A 19" Monochrome Monitor On One's Bare Feet.

***************************

A frequently overlooked feature of the DCL RENAME command is
its ability to move directory trees to new locations on the
same disk.

Say you have a whole mess of files in a subdirectory
like [JONES.TEST.FEBRUARY.DCL]. You want to move the entire
.TEST subdirectory to a separate directory on the drive.
Instead of creating the new directories, copying the files
there, and deleting the originals, you can simply issue
the command:

$ RENAME [JONES]TEST.DIR DISK:[000000]TEST.DIR

The new directory, [TEST], will contain the [.FEBRUARY] and
[.DCL] subdirectories and all of their files. Of course,
make certain you don't attempt to create a new directory
where one with the same name already exists.

***************************

Ever wonder what files are being accessed by that command
file or program you're running? An undocumented DCL command,
SET WATCH, can provide you with an extraordinary amount
of information about your process' file system operations.

To see if you can use the command, check that
SYS$SYSTEM:SETWATCH.EXE exists on your system. You also need
CMEXEC (change mode to executive) privilege, or you'll
have to ask your system manager to install the image
with the privilege, if your site's security requirements
permit it.

The command form is:

$ SET WATCH FILE/CLASS=(classname)

The more interesting class names include:

ALL (self-explanatory)
ATTRIBUTES (show file attribute modifications)
CONTROL_FUNCTION (show protection changes)
DIRECTORY_OPERATIONS (show all directory accesses)
DUMP (dump file information block)
MAJOR_FUNCTION (file reads, writes, opens, closes)
NONE (use to disable SET WATCH)
QUOTA_OPERATIONS (Disk quota changes)

If I enter

$ SET WATCH FILE/CLASS=DIRECTORY

then issue the command:

$ DIR

the system will display:

%XQP-I-FUNCTION, Directory scan for: BARKES.DIR;1, Status: 00000001
%XQP-I-FUNCTION, Read only directory access (13,1,0)
%XQP-I-FUNCTION, Directory scan for: PROPRESS.DIR;1, Status: 00000001
%XQP-I-FUNCTION, Read only directory access (66,8,0)
%XQP-I-FUNCTION, Directory scan for: DCL92.DIR;1, Status: 00000001

Directory USER2:[BARKES.PROPRESS.DCL92]

BARKES.FEB92;1      BARKES.JAN92;3      BARKES.TJL;1        

Total of 3 files.

The SET WATCH function is turned off by entering:

$ SET WATCH FILE/CLASS=NONE

***************************

You may ask, where does one find all these nifty
undocumented commands? Joe Meadows, Jr. freely distributes a
program he wrote, VERB, which extracts DCL command
definitions from your process space or a command table file,
such as SYS$SHARE:DCLTABLES.EXE.

By comparing the output of VERB to the official DEC
documentation, you can pinpoint commands "hidden" within
DCL. VERB uncovered the following on SET WATCH:

define syntax SET_WATCH
   image SETWATCH
   parameter P1, label=OPTION
      value (required)
   parameter P2, label=WATCH_OPTION, prompt="What"
      value (required,type=WATCH_OPTIONS)
   qualifier CLASS
      value (required,list,type=WATCH_CLASSES)
   disallow not CLASS

define type WATCH_OPTIONS
   keyword FILE

define type WATCH_CLASSES
   keyword ALL, negatable
   keyword ATTRIBUTES, negatable
   keyword CONTROL_FUNCTION, negatable
   keyword DIRECTORY_OPERATIONS, negatable
   keyword DUMP, negatable
   keyword ATTACHED, negatable
   keyword MAJOR_FUNCTION, negatable
   keyword NONE
   keyword QUOTA_OPERATIONS, negatable

VERB was used to uncover the /FOREIGN qualifier to the
MAIL utility mentioned here last year. It also reveals
such goodies as the CHECKSUM command and the /ANALYZE qualifier
to backup.

***************************

Kevin G. Barkes is an independent consultant who sometimes
finds the documented DCL commands more than sufficiently
puzzling. He can be found lurking on comp.os.vms or reached
at kgbarkes@gmail.com.