Chapter 4. Devices, Linux Filesystems, and the Filesystem Hierarchy Standard (Topic 2.4)

Filesystem management is among the most critical activities that you must perform to maintain a stable Linux system. In simple situations, after a successful installation, you may never have a problem or need to manage filesystem specifics. However, understanding how to configure and maintain Linux filesystems is essential to safely manage your system and to pass Exam 101. This section contains these Objectives:

Objective 1: Create Partitions and Filesystems

Most Linux distributions will automate initial filesystem creation on your system for you. However, subsequent management of partitions, particularly on large systems and multiboot configurations, requires specific knowledge. This Objective involves the creation of disk partitions using fdisk, and filesystem creation using mkfs. Weight: 3.

Objective 2: Maintain the Integrity of Filesystems

At one time or another, you will probably find yourself stuck with an ailing filesystem. It could be a small problem resulting from a system crash, or it could be a total disk failure. Whatever the cause, you must be prepared to work with fsck to repair problems. This Objective also covers the handy du and df commands, which will help you with monitoring filesystem properties. Weight: 5.

Objective 3: Control Filesystem Mounting and Unmounting

Under Linux, a filesystem is not available for use unless it is mounted. When the system boots, it mounts its filesystems according to instructions in the important /etc/fstab file. This Objective covers the management of this file, manual mounting of filesystems, and configuration of user-mountable removable filesystems. Weight: 3.

Objective 4: Set and View Disk Quotas

When running a system with multiple users, you may find some of them competing for disk space. Managing that problem gets much easier when you enforce disk quotas, which allocate finite amounts of space to individual user accounts. Setup and management of quotas is covered by this Objective. Weight: 1.

Objective 5: Use File Permissions to Control Access to Files

Linux file permissions are a critical part of any system's security policy. This Objective covers permissions on files and directories, including special modes. Weight: 3.

Objective 6: Manage File Ownership

File ownership is a fundamental part of the access control described in Objective 5. This Objective covers the management of user and group ownership. Weight: 2.

Objective 7: Create and Change Hard and Symbolic Links

The Linux filesystem allows the creation of filesystem links. Links allow multiple filenames to point to the same file, a handy way of having the same file appear in more than one place or under different names. This Objective covers both hard and soft (symbolic) links. Weight: 2.

Objective 8: Find System Files and Place Files in the Correct Location

Linux distributions share a common Filesystem Hierarchy Standard (FHS), which describes where files are located in the filesystem and how they are named. This Objective covers that standard, as well as methods of locating files. Weight: 2.