Systems level I/O - How to make systems talk to each other

A core aspect of writing system software is to write it in a way that it can communicate with other software. These can be distributed systems in the cloud or on multiple servers, but also multiple systems on a single machine interacting with each other. To work together, systems have to exchange information with each other. There are a few different ways of doing this, which we are going to learn about in this section. All ways use some form of input/output (I/O), which refers to the process of copying data from external devices to main memory (input) or from main memory to external devices (output) [Bryant03].

In this chapter, we will learn about how to perform I/O with various external devices, such as the disk, a network or a terminal. In addition to that, we will learn about ways that the operating system provides to exchange signals between processes running on the same machine.

Here is the roadmap for this chapter:

• 6.1. The file abstraction
• 6.2. Network communication
• 6.3. Interprocess communication using signals and shared memory
• 6.4. Command line arguments, environment variables and program exit codes