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The UNIX File System Structure

The Hierarchical File Structure

The file system of the UNIX and Linux operating systems is hierarchical in nature, and is frequently called a tree-structured file system because it resembles an upside down tree. At the beginning of this inverted tree is the root directory, which is typically called root.

The root directory is represented by the / (forward slash) character. All other files and directories on the system, regardless of what physical storage device they may reside on, are located below the root directory. The following diagram is a visual representation of the file system structure:





Absolute and Relative Pathnames

A file or directory (a container for one or more files) in the file system can be referenced by either its absolute or relative pathname. The absolute pathname is the path to a file or directory starting at the root directory (/). The relative pathname is the path to a file or directory starting from, or in relation to, your current location (directory) in the file system.

To understand this better, let's look at a file named myfile2 that is located in /home/jdoe/docs




The absolute pathname to myfile2 would be:

/home/jdoe/docs/myfile2

If you are currently in the /home/jdoe directory, the relative path to myfile2 would be:

docs/myfile2

Notice how there is no / prior to the docs directory. If a / was included, this would indicate an absolute path from the root directory and myfile2 would not be found because there is not a docs directory immediately below the root directory.

Read the NEXT article in this series - Standard UNIX & Linux Operating System Directories