O'Reilly logo

Advanced Programming in the UNIX® Environment, Third Edition by Stephen A. Rago, W. Richard Stevens

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

3. File I/O

3.1. Introduction

We’ll start our discussion of the UNIX System by describing the functions available for file I/O—open a file, read a file, write a file, and so on. Most file I/O on a UNIX system can be performed using only five functions: open, read, write, lseek, and close. We then examine the effect of various buffer sizes on the read and write functions.

The functions described in this chapter are often referred to as unbuffered I/O, in contrast to the standard I/O routines, which we describe in Chapter 5. The term unbuffered means that each read or write invokes a system call in the kernel. These unbuffered I/O functions are not part of ISO C, but are part of POSIX.1 and the Single UNIX Specification.

Whenever we describe ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required