OpenVMS

OpenVMS (Open Virtual Memory System or just VMS) is an operating system, originally developed by Digital Equipment Corp., but now owned by VMS Software, Inc.

Supported Oracle products

Oracle 10g and Oracle RDB is currently suppported on OpenVMS. See Oracle's August 2007 statement of direction at http://www.oracle.com/partnerships/hw/hp/vms-directions.pdf

The VMS operating environment

DCL Commands

VMS provides a command line interface with a shell language called DCL. DCL has a rich set of commands and can be used to create script files (known as command procedures in VMS-speak). VMS commands tend to be meaningful and English (unlike their Unix counterparts) and are NOT case sensitive.

Some of the main commands are:

DIRECTORY	list contents of a directory
SHOW DEFAULT	to show current working directory
SET DEFAULT	to change current working directory
EDIT filename	to edit a file!
TYPE filename	to list a file's contents on screen
HELP	to get on-line help
SEARCH	to search a set of files for a string
DELETE filename	deletes the file
PURGE filename	delete old versions of the file
RENAME	rename the file
RUN filename	runs a program - all programs have an extension .EXE
@filename	runs a command procedure (has a .COM extension)

Only the first significant characters of a command need to be entered, e.g. DIRECTORY can be shortened to DIR. Command shortcuts can also be created, e.g. entering the command

PWD :== SHOW DEFAULT

will allow you to use the command PWD instead of show default and entering

CD :== SET DEFAULT

will allow the use of CD to change directories.

File Specifications

File specifications are a little different in VMS from other operating systems. For instance the windows file specification c:\windows\system\readme.txt would look a little like the following in VMS:

DUA0:[WINDOWS.SYSTEM]README.TXT;1

The ;1 indicates version 1 of the file. VMS creates a new version of a file when it is changed (don't you wish DOS did this). You can however start eating large amounts of disk space with multiple versions of the file so regular use of the PURGE command is recommended.

Logical Names

Another great feature of VMS is the use of logical names. A logical name can be used to represent a complete directory or file specification, the directory DUA0:[USERS.ADRIAN.DEVELOPMENT.CODE] could be represented by the logical name CODE$DIR. Instead of having to type in the complete directory specification to set default to this directory, I can instead type in CD CODE$DIR. Logical names are created using the DEFINE command.

One very useful feature of logical names is it permits location independence for files. In the above example the directory can be renamed or moved to a different disk and provided the logical name is changed any commands or programs using the directory will still work. I would recommend that wherever a directory specification is required (either in a program or command file) a logical name is used instead. ORACLE on VMS makes extensive use of logical names.

There is no real equivalent of a path in VMS. Logical names provide a much more flexible and manageable architecture than Unix or Dos paths. (It is actually possible to set up a logical name to point to several directories which performs a similar function to setting up a path).

Customizing the user environment

Each user on VMS will normally have a command file which is automatically invoked upon login. By default the file is called LOGIN.COM and resides in the users login directory (pointed to by the logical name SYS$LOGIN). Any user defined logical names and command shortcuts can be set up in this file.

Also see

• Oracle on VMS FAQ, frequently asked questions.

External links

• HP's OpenVMS home page
• OpenVMS.org
• Oracle/VMS SIG