HP NonStop G-Series - Manual (Page 52)

Managing Files With TACL
Guardian User’s Guide — 425266-001
3 -2
Introduction to Files in Guardian
Introduction to Files in Guardian
On a Compaq NonStop™ Kernel system, a file on the Guardian operating system can
be:
•
Disk files, which can contain data, code, or text
•
Nondisk devices, such as terminals, printers, or tape drives
•
Processes (programs that are running)
You always refer to a file by its file name. For disk files, the user or process who creates
the file gives it a name. Nondisk devices have assigned names in the system. Processes
can be named by their creator or can be assigned a name by the operating system.
A disk file name includes the file’s node, volume, subvolume, and file identifier. File
names for devices other than disks and processes begin with a dollar sign ($) followed
by one to five alphanumeric characters. For example:
$DAISY (a printer name)
$CMON (a process name)
$CD55 (a process name)
\WEST.$DATA.SEND.MSGS (a disk file name)
Types of Disk Files
You can create disk files to store databases, coded programs, or text. For most uses, you
should create the specific type of file that best suits your purpose. Even if you do not
create your own files, you might work with various types of files and need to perform
FUP operations on those files.
Enscribe, the NonStop™ Kernel database record manager, supports four disk file types:
•
Unstructured files
•
Key-sequenced files
•
Entry-sequenced files
•
Relative files
An unstructured file is an array of bytes of data. The organization of an unstructured file
is determined by its creator; unstructured files often contain program code or text.
The other file types are all structured files. A structured file is designed to contain a
database. The database contains logical records (individual sets of data about separate
items or people). Each type of structured file uses a different structured organization.
The ENSCRIBE Programmer’s Guide describes the three types of structured files.
When you create a file, you can use FUP to specify the structure of the file. You select
the file structure to match the type of data you want to store in the file.
Section 8, Using
FUP for Advanced File Management , demonstrates how to select file characteristics and
create both structured and unstructured files with FUP.