The ‘genfstab’ command is an Arch Linux install script used to generate output suitable for addition to an fstab file. It can display an fstab compatible output based on either a volume label or a volume UUID. It is commonly used to generate an fstab file and automatically append a volume to it for automatic mounting.

Use case 1: Display an fstab compatible output based on a volume label

Code:

genfstab -L path/to/mount_point

Motivation: This use case is helpful when you want to display an fstab compatible output based on the volume label of a particular mount point. It allows you to easily view the necessary information required for adding the volume to the fstab file.

Explanation:

• genfstab: The command itself.
• -L: Specifies that you want to generate the output based on a volume label.
• path/to/mount_point: The path to the mount point for which you want to generate the fstab output.

Example Output:

LABEL=ARCH_ROOT / ext4 rw,relatime,data=ordered 0 1
LABEL=SWAP none swap defaults 0 0

Use case 2: Display an fstab compatible output based on a volume UUID

Code:

genfstab -U path/to/mount_point

Motivation: This use case is useful when you want to display an fstab compatible output based on the volume UUID of a specific mount point. It allows you to easily obtain the necessary information for adding the volume to the fstab file.

Explanation:

• genfstab: The command itself.
• -U: Specifies that you want to generate the output based on a volume UUID.
• path/to/mount_point: The path to the mount point for which you want to generate the fstab output.

Example Output:

UUID=123e4567-e89b-12d3-a456-426655440000 / ext4 rw,relatime,data=ordered 0 1
UUID=456e89b-123a-4564-2655-440000426655 none swap defaults 0 0

Use case 3: Generate an fstab file, requiring root permissions

Code:

genfstab -U /mnt >> /mnt/etc/fstab

Motivation: This use case is commonly used to generate an fstab file in the “/mnt/etc/fstab” location. It is typically executed during the Arch Linux installation process, as it allows the creation of the fstab file with the required root permissions.

Explanation:

• genfstab: The command itself.
• -U: Specifies that you want to generate the output based on a volume UUID.
• /mnt: The mount point for which you want to generate the fstab file.
• >>: Appends the output to the specified file.
• /mnt/etc/fstab: The path to the fstab file.

Example Output: No output is displayed on the screen. The generated fstab file is located at “/mnt/etc/fstab”.

Use case 4: Append a volume into an fstab file to mount it automatically

Code:

genfstab -U path/to/mount_point | sudo tee -a /etc/fstab

Motivation: This use case is useful when you want to append a specific volume to the fstab file in order to mount it automatically. The ‘sudo tee’ command allows writing to the /etc/fstab file as the root user.

Explanation:

• genfstab: The command itself.
• -U: Specifies that you want to generate the output based on a volume UUID.
• path/to/mount_point: The path to the mount point for which you want to generate the fstab output.
• |: Pipes the output of the ‘genfstab’ command to the ’tee’ command.
• sudo tee -a /etc/fstab: ’tee’ is used to write the output to the specified file with root permissions.

Example Output: No output is displayed on the screen. The specified volume is appended to the “/etc/fstab” file for automatic mounting.

Conclusion:

The ‘genfstab’ command is a handy tool for generating an fstab compatible output based on either volume labels or UUIDs. It simplifies the process of creating or appending volumes to the fstab file, which enables the automatic mounting of these volumes. Whether you need to view the output, create an fstab file, or append a volume to it, the ‘genfstab’ command provides the necessary functionality for managing fstab entries efficiently.