Linux Interprocess communications

                               

  Linux Interprocess communications

B. Scott Burkett, scottb@intnet.net v1.0, 29 March 1995

6.1 Introduction

The Linux IPC (Inter-process communication) facilities provide a method for multiple processes

to communicate with one another. There are several methods of IPC available to

Linux C programmers:

• Half-duplex UNIX pipes

• FIFOs (named pipes)

• SYSV style message queues

• SYSV style semaphore sets

• SYSV style shared memory segments

• Networking sockets (Berkeley style) (not covered in this paper)

• Full-duplex pipes (STREAMS pipes) (not covered in this paper)

These facilities, when used effectively, provide a solid framework for client/server development

on any UNIX system (including Linux).

6.2 Half-duplex UNIX Pipes

6.2.1 Basic Concepts

Simply put, a pipe is a method of connecting the standard output of one process to the

standard input of another. Pipes are the eldest of the IPC tools, having been around since

the earliest incarnations of the UNIX operating system. They provide a method of one-way

communications (hence the term half-duplex) between processes.

This feature is widely used, even on the UNIX command line (in the shell).

ls | sort | lp