101-500 Exam Dumps : LPIC-1 Exam 101, Part 1 of 2, version 5.0

The timeout option in a GRUB Legacy configuration file is used to define the amount of time (in seconds) that the GRUB menu will be shown to the user before booting the default entry. The timeout option is usually located in the /boot/grub/menu.lst file. For example, timeout 10 will display the GRUB menu for 10 seconds. To disable the timeout and wait for user input indefinitely, the value of timeout can be set to -1. To boot immediately without displaying the menu, the value of timeout can be set to 0. The other options are not valid for the GRUB Legacy configuration file. References:

• GRUB Legacy - ArchWiki
• How do I set the grub timeout and the grub default boot entry?
• How to Remove the Timeout From GRUB Menu

The export command is a Bash built-in command that exports environment variables and functions for use in other shell sessions1. Environment variables are named values that affect the behavior of applications and processes2. For example, the PATH variable stores a list of directories where executable programs are located, and the LANG variable sets the language and locale of the system2. By using the export command, you can make these variables available to any child process spawned by the current shell1. For example, if you want to set the EDITOR variable to vim for all subshells, you can run:

export EDITOR=vim

The export command can also be used to export functions, which are blocks of code that can be reused by invoking their name3. For example, if you want to create and export a function that prints “Hello world”, you can run:

hello () { echo “Hello world”; } export -f hello

Then, you can call the hello function in any subshell or script that inherits the environment from the current shell.

The other options are not related to the export command. Option A refers to the mount command, which attaches a filesystem to a directory4. Option B refers to the command substitution feature, which runs a command in a subshell and replaces it with its output5. Option C refers to the history command, which displays the command history of the current shell. Option E refers to the exportfs command, which maintains the table of exported NFS shares.

References:

• [LPI Linux Essentials - 1.3 Basic Editing]
• [LPI Linux Essentials - 1.4 I/O Redirection]
• [LPI Linux Essentials - 1.5 Manage Simple Partitions and Filesystems]
• Linux export Command with Examples - phoenixNAP
• bash - What does "export" do in shell programming? - Stack Overflow
• How to Use Export Command in Linux [Explained for Beginners]
• mount(8) - Linux manual page
• Command Substitution - Bash Reference Manual
• [history(3) - Linux manual page]
• [exportfs(8) - Linux manual page]

The apt-get subcommand that installs the newest versions of all currently installed packages is dist-upgrade. The dist-upgrade subcommand performs the same function as the upgrade subcommand, which is to install the latest versions of the packages that are already installed on the system, but it also intelligently handles the dependencies and removes the obsolete packages if necessary. The dist-upgrade subcommand is useful when upgrading the entire system to a new release or distribution12.

The other options are either invalid or do not perform the desired task. The auto-update subcommand does not exist, and the update subcommand only updates the list of available packages from the repositories, but does not install any packages. The full-upgrade subcommand is an alias for the dist-upgrade subcommand, so it performs the same function, but it is not the standard name for the subcommand. The install subcommand installs new packages or specific versions of packages, but it does not upgrade all the currently installed packages. References:

• Linux Essentials - Linux Professional Institute Certification Programs1
• Exam 101 Objectives - Linux Professional Institute2
• APT-GET Command in Linux {Detailed Tutorial With Examples} - phoenixNAP3
• How do I get help on apt-get’s install subcommand?
• APT Cheat Sheet | Packagecloud Blog