101-500 Exam Results

 The Logical Volume Manager (LVM) is a tool that allows the creation and management of logical volumes on Linux systems. Logical volumes are partitions that can span multiple physical disks and can be resized or deleted without affecting the rest of the system. Some of the benefits of using LVM are:

• To dynamically change the size of logical volumes. LVM allows the user to increase or decrease the size of a logical volume without having to repartition the disk or reboot the system. This can be useful for allocating more space to a volume that is running out of space, or freeing up space from a volume that is not needed anymore.
• To create snapshots. LVM allows the user to create a snapshot of a logical volume, which is a copy of the volume at a certain point in time. Snapshots can be used for backup purposes, as they can be restored to the original volume if needed. Snapshots can also be used for testing purposes, as they can be mounted as read-only or read-write volumes without affecting the original volume.
• To dynamically create or delete logical volumes. LVM allows the user to create or delete logical volumes on the fly, without having to repartition the disk or reboot the system. This can be useful for creating temporary volumes for specific purposes, or deleting volumes that are no longer needed.

LVM cannot be used for the following purposes:

• To create RAID 9 arrays. RAID 9 is not a valid RAID level, and LVM does not support RAID functionality. RAID is a technique that uses multiple disks to provide redundancy, performance, or both. RAID can be implemented at the hardware level, by using a RAID controller, or at the software level, by using tools such as mdadm or dmraid. LVM can work on top of RAID devices, but it cannot create them.
• To encrypt logical volumes. LVM does not provide encryption functionality. Encryption is a technique that protects data from unauthorized access by using a secret key to transform the data into an unreadable form. Encryption can be implemented at the disk level, by using tools such as dm-crypt or LUKS, or at the file system level, by using tools such as eCryptfs or EncFS. LVM can work on top of encrypted devices, but it cannot encrypt them.

References:

• LPI Linux Essentials - Topic 3: Command Line Operations
• LPI Linux Essentials - Topic 4: User Interfaces and Desktops
• LPI Linux Essentials - Topic 5: Administrative Tasks
• LPI Linux Essentials - Topic 6: Essential System Services
• LPI Linux Essentials - Topic 7: Networking Fundamentals
• LPI Linux Essentials - Topic 8: Security Fundamentals
• LPI Linux Essentials - Topic 9: Basic Scripting
• LPI Linux Essentials - Topic 10: IT Explorations
• LPI Linux Essentials - Topic 11: Finding Your Way on a Linux System
• LPI Linux Essentials - Topic 12: The Power of the Command Line
• LPI Linux Essentials - Topic 13: The Linux Operating System
• LPI Linux Essentials - Topic 14: Security and File Permissions
• LPI Linux Essentials - Topic 15: Basic Linux System Administration
• LPI Linux Essentials - Topic 16: Quotas
• LPI Linux Essentials - Topic 17: Managing Users and Groups
• LPI Linux Essentials - Topic 18: Ownership and Permissions
• LPI Linux Essentials - Topic 19: Special Permissions and Attributes

 The dpkg-reconfigure command is used to reconfigure an already installed package. It asks configuration questions for the package, just as if the package were being installed for the first time. This can be useful if the user wants to change some settings or options for the package without reinstalling it. The dpkg-reconfigure command can also be used to fix a broken package configuration or to restore the default settings. References:

• dpkg-reconfigure(8) - Linux man page
• Linux Professional Institute: Exam 101 Objectives

After modifying GNU GRUB’s configuration file, which is usually located at /etc/default/grub, the command that must be run for the changes to take effect is grub-install12. The grub-install command is used to install GRUB on a device or partition, and to update the boot sector and the core image of GRUB3. The command takes the following basic syntax:

$ grub-install [options] install_device

The install_device argument specifies the device or partition where GRUB should be installed, such as /dev/sda or /dev/sda1. The options can be used to control various aspects of the installation, such as the target platform, the boot directory, the force mode, the verbosity level, etc3.

The grub-install command also invokes the grub-mkconfig command, which generates the GRUB configuration file (usually located at /boot/grub/grub.cfg) based on the settings in /etc/default/grub and the scripts in /etc/grub.d4. The grub-mkconfig command can also be run separately to update the GRUB configuration file without reinstalling GRUB on the device or partition4.

The other options in the question are not correct because:

• A. kill -HUP $(pidof grub): This command would send the hangup signal (HUP) to the process ID (PID) of grub, which is a command-line interface for GRUB. This would not update the GRUB configuration file or install GRUB on the device or partition.
• C. grub: This command would run the command-line interface for GRUB, which allows the user to interact with GRUB and execute various commands. This would not update the GRUB configuration file or install GRUB on the device or partition, unless the user explicitly runs the appropriate commands within the interface.
• D. No action is required: This option is false, because modifying the /etc/default/grub file alone does not affect the GRUB configuration file or the GRUB installation. The user needs to run either grub-install or grub-mkconfig to apply the changes.

References:

1: How to Update Grub on Ubuntu and Other Linux Distributions - It’s FOSS 2: How to Configure the GRUB2 Boot Loader’s Settings 3: Ubuntu Manpage: grub-install - install GRUB on a device 4: [GNU GRUB Manual 2.06: Invoking grub-mkconfig] : [GNU GRUB Manual 2.06: Invoking grub] : [kill(1) - Linux manual page] : [pidof(8) - Linux manual page] : [grub(8) - Linux manual page]