Compaq COBOL AAQ2G1FTK, Руководство пользователя

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Sharing Files and Locking Records
8.3 Ensuring Successful File Sharing
In the OpenVMS Alpha file protection facility, four different categories of users
exist with respect to data structures and devices. A file owner determines which
of the following user categories can share the file:
• SYSTEM—Users of the system whose group numbers are in the range 0 to
the value of the MAXSYSGROUP parameter or who have certain I/O-related
privileges
• OWNER—Users of the system whose UIC group and member numbers are
identical to the UIC of the file owner
• GROUP—Users of the system whose group number is identical to the group
number of the file owner
• WORLD—All other users of the system who are not included in the previous
categories
The OpenVMS Alpha operating system applies a default protection to each newly
created file unless the owner specifically requests modified protection.
For more information on file protection, refer to the OpenVMS User’s Manual.
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Note
The following Tru64 UNIX operating system file access types are not a
part of Compaq COBOL syntax.
On Tru64 UNIX systems, the three types of file access are as follows:
• Read—Permits the reading of the records in the file.
• Write—Permits updating or extending the records in the file.
• Execute—Applies to image execution and is therefore not applicable to a
Compaq COBOL program.
There are three categories of users:
• User—Owner of the file
• Group—Users in the same group as the owner
• Others—All other users
Compaq COBOL determines the access permission for newly created files in the
following manner:
1. The default access permissions are granted:
• User and Group are granted read and write access.
• Others are granted read access.
2. Then the file mode creation mask of the process creating the file is taken into
account.
Additional information on file permission can be found in the Tru64 UNIX man
pages for
chmod, ls, open,
and
umask
.
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Sharing Files and Locking Records 8–5