Using Unix means being part of a global system for collaborative computing. The ability to connect with and perform interactive tasks on other Unix machines is built into Mac OS X and every other version of Unix in use today.
Most of the interactions you have with other Unix machines will fall into one of two categories: logging in to another machine to get a command-line interface on the remote machine, or copying files between your machine and a remote machine.
Technically speaking, the programs we describe in this chapter are not limited to interacting with Unix machines; the underlying requirement is simply that they understand the lingua franca of the Internet, TCP/IP. However, Unix is so prevalent that chances are, the system you connect to will be Unix based. The basics of interaction with non-Unix machines, as well as more advanced forms of interaction, such as setting up virtual private networks and automated (unattended) file transfers, are beyond the scope of this book. We will, however, guide you to places where you can learn more about what is possible and how to do it.