The Unix data storage facility is a collection of directories containing files and other directories. These files and directories are organized in a hierarchical structure with the root (/) directory as the starting point. Therefore, Unix data storage is organized in the form of an inverted tree, with directories as branches and files as leaves.
Metacharacters are characters or combinations of characters that can represent all or portions of directory names or filenames. With metacharacters, you can use a short phrase to represent a longer directory/file name or even a series of directory/file names. The three standard shells (Bourne, C, and Korn) support the metacharacters listed in Table 10.1.