Often abbreviated as UFS, the Unix File System provides data storage and organization for Unix and Unix-based operating systems. Based on the file system seen in Version 7 Unix, the file system has a maximum volume size and file system of 8 zebibytes.

Common UFS Implementations
Many software vendors use UFS in their proprietary Unix operating systems. This includes:

• SunOS / Solaris
• System V Release 4
• HP-UX
• Tru64 UNIX
• Illumos

While there is a certain level of cross-compatibility between these platforms, full compatibility is considered spotty.

Common System Directories
Although some implementations may contain additional (or fewer) system files, there are some files that are included in most Unix file systems.

• bin: An abbreviated for "binaries," this directory stores many commonly used executable commands.
• dev: This directory contains various files that pertain to specific devices within your system.
• etc: Various system configuration files are found in this directory.
• home: Files and user directories are contained within this directory.
• lib: An abbreviation for "library," this directory houses your system's library files.
• mnt: An abbreviation for "mounted," this directory contains files that pertain to your system's mounted devices.
• proc: Files that are needed for various system processes are contained here.
• root: This directory is reserved for files created and stored by the root user.
• sbin: An abbreviation for "system binaries," this directory contains system-specific executable commands. In the absence of an sbin directory, these files are typically found in the etc folder.
• tmp: This directory provides storage for temporary files.
• usr: Additional executable commands are stored in this directory.

Most of these directories are self-explanatory, but they can be confusing to a novice user. To further clarify their importance, it helps to understand some of the most common file types found in the UFS.

Common File Types
The UFS treats every component of your system as an individual file. This includes virtual elements like directories and actual files as well as physical components like hard drives and printers. Most Unix file systems, including the UFS, contain six default file types, or categories.

• Directories: These are similar to folders in Windows and Mac operating systems. Each Unix directory maintains an entry for every single file and directory in the system.
• Ordinary files: These files contain some amount of text, data, or program-specific coding.
• Special files: Physical devices such as printers and hard drives are represented by special files.
• Pipes: Various commands can be linked together in the Unix OS using a pipe. It's essentially a temporary file that maintains a one-way flow of information or data.
• Sockets: Unix sockets are used for inter-process communications on a localized scale, similarly to how network sockets are used online.
• Symbolic link: References to other files are contained with symbolic or soft links. It appears to the user as an ordinary file, but it points to another file on the system.

Now that you have a better understanding of the common system directories and file types, you're well on your way to learning the Unix file system.

You may read more about the Unix File System (UFS) in Wikipedia: Unix File System.