File Systems

Although all the files in your Linux system are connected into one overall directory tree, parts of that tree may reside on different storage devices such as hard drives or CD-ROMs. Files on a particular storage device are organized into what is referred to as a file system. A file system is a formatted device, with its own tree of directories and files. Your Linux directory tree may encompass several file systems, each on different storage devices. On a hard drive with several partitions, you would have a file system for each partition. The files themselves are organized into one seamless tree of directories, beginning from the root directory. For example, if you attach a CD-ROM to your system, a pathname will lead directly from the root directory on your hard disk partition's file system to the files in the CD-ROM file system.

Tip

With Linux, you can mount file systems of different types, including those created by other operating systems, like Windows, IBM OS, Unix, and SGI. Within Linux a variety of files systems is supported, including several journaling systems like ReiserFS and ext3.

A file system has its files organized into its own directory tree. You can think of this as a subtree that must be attached to the main directory tree. The tree remains separate from your system's directory tree until you specifically connect it. For example, a floppy disk with Linux files has its own tree of directories. You need to attach this subtree to the main tree on your hard drive partition. Until they are attached, you cannot access the files on your floppy disk.