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OpenVMS Undocumented Features


This is the most complete collection of undocumented features we can find for OpenVMS. Some of these have been around since the time when it was called VMS while others are more current and have been added to OpenVMS V8.n. These features:

  • Are NOT documented (if they were, they wouldn't belong here)
  • Are NOT supported by PARSEC Group or HP
  • Are NOT guaranteed to work
  • May NOT exist in all versions of OpenVMS; past, present and future
  • Are subject to change, removal, enhancement or being documented at the whim of OpenVMS engineering
  • May be fun to know the next time you play OpenVMS trivial pursuit
  • May help you get your job done easier and faster
  • May help you impress your boss with your knowledge of the obscure

DS Series Sound Command

The DS series AlphaServers include a SOUND command on the console. This command plays the "Yellow Rose of Texas".

Logical names controlling OPCCRASH

The following logical names are used by SHUTDOWN.COM to control the actions taken by OPCCRASH. These may be defined by a system manager preparing the invoke a disorderly shutdoing using OPCCRASH. Setting any of these logical names to the value T, Y or 1 causes its action to be invoked.

OPCCRASH Logical Names
OPC$CLUSTER_SHUTDOWN Causes this node to remain a member of the cluster until all nodes in the cluster reach this point. This allows a shutdown to be performed without any node hanging due to lost quorum.
OPC$GALAXY_SHUTDOWN Causes OpenVMS/Galaxy to be shut down.
OPC$POWER_OFF Causes system to be powered off if the hardware supports it.
OPC$REBOOT Causes an automatic reboot to be initiated.
OPC$REMOVE_NODE Informs other nodes of the cluster that this node's votes should be removed from the cluster expected votes.
OPC$UNLOAD Causes the system disk to be spun down if it supports it.

Mail transport

VMS Mail supports multiple transports. Each user may set and view the transport to be used. Setting the transport functions the same as entering that transport name before each email address entered. It is not necessary to set the SMTP transport since VMS mail can detect when that transport is needed and add it automatically. Some third-party mail applications may require that this be set to a specific transport that is supplied with their application.

$ mail

MAIL> set transport smtp%

MAIL> show transport
Your default transport is SMTP%.

MAIL> set notransport

MAIL> exit

MONITOR Commands

The MONITOR utility includes the ability to monitor classes other than those which are documented. These include the ETHERNET, JDEVICE, VMS1 and VMS2 classes. The only problem is that the decision was made to somewhat disable the functionality in the released code. Note in the example below, if an invalid class name is specified, an error message is displayed; however, if the ETHERNET or one of the other undocumented classes is specified, there is no error message. In the past, there have been some patches created that eliminated the return instruction from the start of the routine for this function which allowed the code to work.

$ monitor invalid
%MONITOR-E-INVCLSNM, class-name "INVALID" is invalid or not uniquely identified
$ monitor ethernet
MONITOR> exit

SDA Extensions

There are many extensions available to SDA. Most of these are not documented. Some may be supplied with third-party applications. To determine which extensions are available, use the DIRECTORY command. The portion of the file name before the dollar sign ($) is the command. To get help on each extension, when available, use one of the following methods.

  • Enter the name of the extension - some extensions will automatically display help information if no subcommands are provided.
  • Enter the name of the extension followed by the command HELP.
  • For the pthread extension, the process context must first be set to a multi-threaded process before entering the PTHREAD HELP command.

$ directory sys$share:*$sda.exe

Directory SYS$COMMON:[SYSLIB]

CLUE$SDA.EXE;1      CNX$SDA.EXE;1       DECDTM$SDA.EXE;1    DKLOG$SDA.EXE;1
EXC$SDA.EXE;1       FC$SDA.EXE;1        FLT$SDA.EXE;1       IO$SDA.EXE;1
IPC$SDA.EXE;1       ISCSI$SDA.EXE;1     LAN$SDA.EXE;1       LCK$SDA.EXE;1
LNM$SDA.EXE;1       MTX$SDA.EXE;1       OCLA$SDA.EXE;1      PCS$SDA.EXE;1
PE$SDA.EXE;1        PKM$SDA.EXE;1       PRF$SDA.EXE;1       PSH$SDA.EXE;1
PTHREAD$SDA.EXE;1   PWIP$SDA.EXE;1      RMS$SDA.EXE;1       SHAD$SDA.EXE;1
SPL$SDA.EXE;1       TCPIP$SDA.EXE;1     TQE$SDA.EXE;1       TR$SDA.EXE;1
USB$SDA.EXE;1       XFC$SDA.EXE;1       XX$SDA.EXE;1

Total of 31 files.

There may also be some extensions residing in different directories and pointed to by logical names. Issueing the command SHOW LOGICAL *$SDA will show those logical names.

Note: Unlike the traditional thinking of SDA being a look only access to the system; with some of these extensions, it is possible that SDA is making changes to the system. Use with extreme caution.


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Please enjoy these features at your own risk. If you are aware of other features in OpenVMS which are currently undocumented, you may use our inquiry form to inform us. We may then add it to our list.