Macintosh Terminal Pocket Guide

Structure of the Filesystem

The OS X filesystem is a hierarchy, or tree, of folders and files, as in Figure 1-5. At the top is a folder called the root directory. Below the root are several folders you might recognize, like Applications, and others that might be less familiar, like bin and etc. These folders-within-a-folder are called subdirectories. Each subdirectory may itself contain other files and subdirectories, and so on, into infinity.

Figure 1-5. The OS X filesystem (partial). The root directory is at the top. The PDF file’s full path is /Users/smith/Desktop/manual.pdf

This filesystem view is not the same one you see in Finder windows. The Finder hides some folders from you, such as etc, because they contain operating system files that most users don’t need to access. It also displays disks and certain folders more prominently, such as Applications, by listing them on the left-hand side of Finder windows. This is just the user-friendly illusion of the desktop. The filesystem tree in Figure 1-5 is the reality.

Folders and Directories

The words “folder” and “directory” are synonyms: they both mean a container for files (and other folders) on your Mac. When using the Finder, people almost always say “folder,” but when using a command line (as in the Terminal and shell), the word “directory” is more common. In this book, we use the terms “directory” and “subdirectory” often.

Each ...