The SAS utilities available for SAS file
management are designed to
enable you to work with more than one SAS file at a time, as long as the files
belong to the same library. The advantage of learning and using SAS Explorer,
functions, options and procedures is that they automatically copy, rename,
or delete any index files or integrity constraints, audit trails, backups
and generation data sets that are associated with your SAS data files. Another
advantage is that SAS utility procedures work on any operating environment
at any level.
There are several SAS window options, functions and procedures available
for performing file management tasks. You can use the following features alone
or in combination, depending on what works best for you. See "Choosing
the Right Procedure" in the
SAS Procedures Guide for detailed information on SAS utility procedures. The SAS windowing
environment and how to use it for managing SAS files is discussed in online
Help.
-
CATALOG procedure
- provides catalog management utilities with the COPY, CONTENTS,
and APPEND procedures.
-
DATASETS procedure
- provides all library management functions for all member
types except catalogs. If your site does not use the SAS Explorer, or if SAS
executes in batch or interactive line mode, using this procedure can save
you time and resources.
-
SAS Explorer
- includes windows that enable you to perform most file management
tasks without submitting SAS program statements. Type LIBNAME, CATALOG or
DIR in the Toolbar window to use SAS Explorer, or select the Explorer icon
from the Toolbar menu.
- DETAILS system option
- Sets the default display for file information when using
the CONTENTS, or DATASETS procedure. When enabled, DETAILS provides additional
information about files, depending on which procedure or window you use.
SAS Explorer and procedures enable you to obtain a list, or directory, of the members in a SAS data library. Each directory contains the
name of each member and its member type. For the member type DATA, the directory
indicates whether an index, audit trail, backup, or generation data set is
associated with the data set. The directory also describes some attributes
of the library, but the amount and nature of this information vary greatly
with the operating environment.
Note: SAS data libraries can also contain
various SAS utility files. These files are not listed in the library directory
and are for internal processing.
|
Accessing Permanent SAS Files without a Libref |
SAS provides you with another method of accessing files in addition
to creating a libref with the LIBNAME statement or using the New Library window.
To use this method, enclose the filename, or the filename and path, in single
quotatation marks.
For example, in a directory based system, if you want to create a data
set named "mydata" in your default directory, that is, in the
directory that you are running SAS in, you can write the following line of
code:
data 'mydata';
SAS creates the data set and
remembers its location for the duration of the SAS session.
If you omit the single quotation marks, SAS creates the data set "mydata"
in the temporary WORK subdirectory, named WORK.mydata:
data mydata;
If you want to create a data set named "mydata"
in a library other than the directory in which you are running SAS, enclose
the entire path in quotation marks, following the naming conventions of your
operating environment. For example, the following DATA step creates a data
set named FOO in the directory C:\sasrun\mydata.
data 'c:\sasrun\mydata\foo';
This method of accessing files works on all operating environments
and in most contexts where a libref.memname is accepted as a SAS dataset.
Most dataset options can be specified with a quoted name.
You cannot use quoted names for:
- a SAS
CATALOG
- MDDB, and FDB references
- contexts that do not accept a libref, such as the SELECT statement
of PROC COPY and most PROC DATASETS statements
- PROC SQL
- DATA step, stored programs or
views
- the Screen Control Language (SCL) open function.
Operating Environment |
Examples |
DOS, Windows |
data 'c:\root\mystuff\sasstuff\work\myfile' ;
|
UNIX |
data '/u/root/mystuff/sastuff/work/myfile';
|
UNIX System Services under OS/390 |
data '/mystuff/sastuff/work/myfile';
|
CMS |
data '< filetype> filemode |* ';
|
OS/390 |
data '/mystuff/sastuff/work/myfile';
|
VAX/ALPHA |
data 'filename filetype filemode';
|
|
Operating Environment Commands |
You can
use operating environment commands to copy, rename, and delete
the operating environment file or files that make up a SAS data library.
However, to maintain the integrity of your files, you must know how the SAS
data library model is implemented in your operating environment. For example,
in some operating environments, SAS data sets and their associated indexes
can be copied, deleted, or renamed as separate files. If you rename the file
containing the SAS data set, but not its index, the data set will be marked
as damaged.
- CAUTION:
- Using operating environment commands can damage
files.
You can avoid problems by always using SAS utilities
to manage SAS files.
|
Sequential Data Libraries |
SAS provides a
number of features and procedures for reading from and
writing to files that are stored on sequential format devices, either disk
or tape. Before you store SAS data libraries in sequential format, you should
consider the following
- You cannot use random access methods with sequential SAS data
sets.
- You can access only one of the SAS files in a sequential library,
or only one of the SAS files on a tape, at any point in a SAS job.
For example, you cannot read two or more SAS data sets in the same
library or on the same tape at the same time in a single DATA step. However,
you can access
- two or more SAS files in different sequential libraries, or on
different tapes at the same time, if there are enough tape drives available
- a SAS file during one DATA or PROC step, then access another SAS
file in the same sequential library or on the same tape during a later DATA
or PROC step.
Also, when you have more than one SAS data set on a tape or in a sequential
library in the same DATA or PROC step, one SAS data set file may be opened
during the compilation phase, and the additional SAS data sets are opened
during the execution phase. For more information, see the SET statement OPEN=
option in the SAS Language Reference: Dictionary
- For some operating environments, you can only read from or write
to SAS data sets during a DATA or PROC step. However, you can always use the
COPY procedure to transfer all members of a SAS data library to tape for storage
and backup purposes.
- Considerations specific to your site can affect your use of tape.
For example, it may be necessary to manually mount a tape before the SAS data
libraries become available. Consult your operations staff if you are not familiar
with using tape storage at your location.
Operating Environment Information: The details for
storing and accessing Version 6 and
Version 5 SAS files in sequential format vary with the operating environment.
See the SAS documentation for your operating environment for further information.
Copyright 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.