Practical UNIX and Internet Security, 3rd Edition

What Is a Deployment Environment?

Unix was developed in the 1970s to be an operating system for minicomputers that were being used simultaneously by several different people. Many of the features of the Unix environment can be traced back to this intended deployment environment.

In the three decades that have followed, Unix has been repurposed to many different kinds of deployment environments. One of the reasons for the operating system’s success is that the design necessary to satisfy the original deployment requirements provided the operating system with great flexibility.

Today Unix is widely used in at least five different deployment environments:

Multiuser, shared systems

This is the original Unix deployment environment—a single computer that is simultaneously shared by several people. Shared systems are still common in universities, in some businesses, and among some Internet service providers. Thin-client Unix systems such as Sun Microsystems’ SunRay systems make use of a shared system driving multiple client displays.

The key difference between the shared systems of the 1970s and the shared systems of today is merely size. In the 1970s, the typical shared Unix system had 32 or 64 KB of RAM, had a disk pack of perhaps 5 MB of storage, and comfortably supported between 3 and 5 simultaneous users. Today’s typical multiuser systems have between 64 MB and 4 GB of RAM, hundreds of GBs of disk storage, and multiple cooperating CPUs, and can comfortably support between 3 and 500 ...