Technical data

Using Files and Directories
10.6 Accessing Disk Files
The contents of HISFILE are displayed on your terminal.
10.7 Accessing Tape Files
This section describes file-level access for tapes. When you request access to a
standard-labeled volume or a file, the operating system checks at the volume and
file level to ensure that your process can access the volume or file. The level at
which the system checks access depends on the operation you request and the
type of access the operation requires.
When you access a volume or a file, the operating system software reads the
volume- and file-header labels to determine whether access to the volume or
file is restricted. Which label is read depends on the operation requested. For
example, if you want to mount a volume, your process must have access to it.
The protection set on a file determines your access to the file. The expiration
date field in the header can prevent you from overwriting or appending to a file
immediately preceding the one in question. If the expiration date field has not
been reached, a file has not expired.
To overwrite an unexpired file, you must specify the /OVERRIDE=EXPIRATION
qualifier when you mount the volume. Performing this operation requires that
you have read or write access.
After a section that explains tape file names are sections that tell how to perform
these tasks:
Task Section
Locate standard-labeled tape files Section 10.7.2
Use wildcards with tape files Section 10.7.3
Read files on tape volumes Section 10.7.4
Write files to tape volumes Section 10.7.5
10.7.1 Understanding Tape File Names
OpenVMS systems accept two types of file names for magnetic tapes:
• OpenVMS extended names
Use OpenVMS extended names if your files are to remain on media using
only the OpenVMS operating system.
• Standard names
Use standard names if you want to move files to media on operating systems
other than OpenVMS.
Table 10–5 compares characteristics of OpenVMS extended names and standard
names.
Table 10–5 Comparison of OpenVMS Extended Names and Standard Names
Characteristic OpenVMS Extended Names Standard Names
Valid with... Tape and disk volumes Tape volumes
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Using Files and Directories 10–23