Chapter 16 shows you the basics of using the command line instead of the Finder for getting around and manipulating files and directories. But nobody would use Terminal if all it could do was move files around. Terminal, like Unix, is much more powerful than that.
This chapter, which assumes that you're already familiar with the Unix commands introduced in Chapter 16, offers guided tutorials for performing more specialized tasks—some of which you can't do in the Finder. These procedures, and the commands you need to perform them, are also starting points for further learning.
Permissions is a largely invisible, but hugely important, Mac OS X and Unix feature. The behind-the-scenes permissions setting for a file or folder determines whether or not you're allowed to open it, change it, or delete it. Permissions are the cornerstone of several important Mac OS X features, including the separation of user accounts and the relative invulnerability of the operating system itself.
You can get a good glimpse at the permissions settings of a file or folder in the Get Info box; see Section 12.10.1 for a discussion. But even there, you're not seeing all of the permission settings Unix provides, and every now and then, you might want to. Suppose, for example, that you're a teacher in charge of a computer lab containing 25 Macs. On each computer, you've created Standard accounts (see Chapter 12) for five students, for a total of 125 ...