Accessing Files Programmer's Guide (32650-90885)

16 Chapter1
Introduction
Disk Files and Device Files
Program examples illustrating various ways to write data from your program to a file are
described in chapter 8, "Writing to a File."
Program examples illustrating various ways to read data from a file are described in
chapter 9, "Reading From a File."
A special method of accessing a file, called update access, is discussed in chapter 10,
"Updating a File."
You can access a file mapped directly through memory loads and stores, thus bypassing the
overhead associated with accessing the file through file system intrinsics. Chapter 11,
"Accessing a File Using Mapped Access" describes mapped access of a file and the
applications where mapped access may increase your program's performance.
There are special considerations you must take into account when you are accessing a file
that is being shared concurrently by others. Chapter 12 ,"Sharing a File" discusses file
sharing methods available to you.
Associated with each account, group, and individual file, is a set of security provisions that
specifies any restrictions on files in that account or group, or to that particular file. These
provisions are discussed in chapter 13, "Maintaining File Security."
MPE/iX provides a number of commands and intrinsics that enable you to obtain
information about your files. You can use the commands and intrinsics described in
chapter 14, "Getting File Information" for a variety of purposes.
The HP Pascal/iX program examples found in appendix A, "HP Pascal/XL Program
Examples" are provided to help you better understand how to use file system intrinsics to
perform file access tasks.