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| Using SAS Files |
Introduction to SAS Files, Libraries, and Engines under OpenVMS
| What Is a SAS File? |
Your data can reside in different types of files, including SAS files and files that are formatted by other software products, such as database management systems. Under OpenVMS, a SAS file is a specially structured OpenVMS file. Although the OpenVMS operating environment manages the file for SAS by storing it, the operating system cannot process it because of the structure built into the file by SAS. For example, you can list the filename with the dir command, but you cannot use a system editor to edit the file. A SAS file can be permanent or temporary.
| What Is a Library? |
An OpenVMS directory can contain many different types of files, including SAS files. All SAS files in a directory that are accessed by the same engine belong to a SAS library. Thus, under OpenVMS, a SAS library is a logical concept rather than a physical one.
Any OpenVMS directory can become a SAS library when SAS files are stored in that directory; a single OpenVMS directory can contain several SAS libraries. (See Multiple SAS Libraries in a Single Directory.) Also, under OpenVMS, several directories can constitute a single SAS library if a search-string logical name is assigned to the series of directories. You can have concatenated libraries using a LIBNAME statement or LIBNAME function. (See Using a Search-String Logical Name to Concatenate SAS Libraries.)
What Is a Libref?
SAS libraries can be identified with librefs. A libref is a name by which you reference the directory in your application. For more information about how to assign a libref, see Assigning Librefs under OpenVMS.
| What Is an Engine? |
SAS files and SAS libraries are accessed through engines. An engine is a set of routines that SAS must use to access the files in the library. SAS can read from and, in some cases, write to the file by using the engine that is appropriate for that file type. For some file types, you need to tell SAS which engine to use. For others, SAS automatically chooses the appropriate engine. The engine that is used to create a SAS data set determines the format of the file.
For more information about engines, see Using SAS Engines.
| Additional Resources |
For more information about SAS files, libraries, and engines, see SAS Language Reference: Concepts.
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Copyright © 2009 by SAS Institute Inc., Cary, NC, USA. All rights reserved.