Free LPI 102-500 Practice Exam with Questions & Answers | Set: 4

The tasks that are handled by a display manager like XDM or KDM are to start and prepare the desktop environment for the user and to handle the login of a user. A display manager is a software component that manages the graphical user interface of an operating system. It provides a login screen where the user can enter their credentials and choose their preferred desktop environment or window manager. After the user is authenticated, the display manager launches the selected desktop environment or window manager and sets up the graphical session. The display manager also handles the logout, shutdown, and reboot of the system.

The other options are incorrect because they are not tasks handled by a display manager:

B. Configure additional devices like new monitors or projectors when they are attached. This task is handled by the X server, which is the core component of the X Window System. The X server is responsible for communicating with the hardware devices, such as the keyboard, mouse, monitor, and graphics card. The X server can detect and configure new devices dynamically using tools like xrandr or xorg.conf.

D. Lock the screen when the user was inactive for a configurable amount of time. This task is handled by the screensaver program, which is a utility that runs in the background and activates when the user is idle for a certain period of time. The screensaver can display various animations or images on the screen, or it can blank the screen entirely. The screensaver can also lock the screen and require the user to enter their password to resume the session. The screensaver can be configured by the user using tools like xscreensaver or gnome-screensaver.

E. Create an X11 configuration file for the current graphic devices and monitors. This task is handled by the X server, which is the core component of the X Window System. The X server can create an X11 configuration file, which is a text file that contains the settings for the X server and the devices it communicates with. The X11 configuration file is usually located at /etc/X11/xorg.conf or /etc/X11/xorg.conf.d/. The X server can generate a default configuration file using the command Xorg -configure, or it can be edited manually by the user or the system administrator. References https://www.baeldung.com/linux/display-managers-explained

https://quizlet.com/185979426/lx0-104-flash-cards/

The xwininfo command is a utility for displaying information about windows on an X server. One of the information it displays is the depth of the window, which is the number of bits per pixel used to represent the color of the window. The depth of the root window, which is the background window of the X server, is the same as the color depth of the X server. To display the depth of the root window, one can use the command xwininfo -root and look for the line that says “depth of root window”. Alternatively, one can use the command xdpyinfo, which displays information about the X server, and look for the line that says “depths of root window”. References:

xwininfo(1) - Linux man page

xdpyinfo(1) - Linux man page

[LPI Linux Certification/Configure the X Window System, Xorg and …]

The xwininfo command is a utility for displaying information about windows in X. It can show various attributes of a window, such as its location, size, depth, border width, visual class, colormap, map state, and event masks. The -metric option specifies that all dimensions should be displayed in metric units (millimeters) rather than pixels. By issuing the xwininfo -metric command and then clicking on a window, the administrator can determine the geometry of that window, including the decorations, in millimeters. References:

xwininfo(1) — Arch manual pages

[command line -

The command that can be used to show the current color depth of the X Server is xwininfo. xwininfo is a command-line tool that provides information about X windows. When executed, it opens a small window and waits for the user to select a window by clicking on it. Then, it displays various characteristics about the window in question, such as its geometry, position, size, depth, class, name, id, and more. The depth value indicates the number of bits per pixel used to represent the colors of the window. xwininfo is part of the X Window System, which is a graphical user interface system for Unix-like operating systems. xwininfo can be useful for debugging, testing, or scripting purposes.

The other options are incorrect because they are either invalid commands or do not show the color depth of the X Server:

xcd is not a valid command in Linux. It may be confused with cd, which is used to change the current working directory.

xcdepth is not a valid command in Linux. It may be confused with xrandr, which is used to change the screen resolution and orientation.

xcolordepth is not a valid command in Linux. It may be confused with xcalib, which is used to load, alter, and query the color profile of the X display.

cat /etc/X11 is not a command, but a directory. cat is used to concatenate files and print them to the standard output. /etc/X11 is a directory that contains configuration files for the X Window System. However, these files do not necessarily show the current color depth of the X Server, as it may be overridden by other settings or options. References:

https://bing.com/search?q=command+to+show+color+depth+of+X+Server

https://x.org/releases/X11R7.5/doc/man/man5/xorg.conf.5.html

The correct SQL query to count the number of occurrences for each value of the field order_type in the table orders is:

SELECT order_type,COUNT(*) FROM orders GROUP BY order_type;

This query uses the SELECT statement to retrieve the values of the order_type field and the COUNT(*) function to count the number of rows for each order_type. The GROUP BY clause groups the rows by the order_type field, so that the count is calculated for each distinct value of order_type. The result of this query is a table with two columns: order_type and count, where each row shows the number of orders for a specific order_type.

The other options are incorrect for the following reasons:

A: This query uses a WHERE clause that is always true, since order_type=order_type for every row. Therefore, this query returns the same result as SELECT order_type,COUNT(*) FROM orders;, which is a table with one row that shows the total number of orders, regardless of the order_type.

C: This query is syntactically invalid, since the COUNT function cannot take a subquery as an argument. The correct way to use a subquery with COUNT is COUNT((SELECT order_type FROM orders));, which returns the total number of orders, regardless of the order_type.

D: This query uses the ORDER BY clause to sort the rows by the order_type field, but it does not group them by order_type. Therefore, this query returns the same result as SELECT COUNT(*) FROM orders;, which is a table with one row that shows the total number of orders, regardless of the order_type.

E: This query is syntactically invalid, since there is no such function as AUTO_COUNT in SQL, and the COUNT function cannot take a field name as an argument. The correct way to use COUNT with a field name is COUNT(order_type);, which returns the number of non-null values in the order_type field.

References:

[SQL COUNT Function]

[SQL GROUP BY Statement]

[SQL SELECT Statement]

The missing word is select, which is the keyword used to query data from a table in SQL. The select statement has the following syntax:

select column_list from table_name where condition;

The column_list can be one or more columns separated by commas, or an asterisk () to indicate all columns. The table_name is the name of the table that contains the data. The where clause is optional and specifies a condition to filter the rows. The count() function is an aggregate function that returns the number of rows in the table or in a group. Therefore, the complete statement is:

select count(*) from tablename;

This statement will return the number of rows in the table named tablename. References: SQL COUNT() Function - W3Schools, SQL COUNT: The Ultimate Guide To SQL COUNT Function - SQL Tutorial, The SQL Count Function Explained With 7 Examples.

The command that allows you to make a shell variable visible to subshells is export VARIABLE. This command turns the variable into a global or environment variable, which means it can be accessed by any child process or subshell that inherits the environment of the parent shell. The syntax of the export command does not require a dollar sign ($) before the variable name, unlike when referencing the value of the variable. The other commands are either invalid or do not affect the visibility of the variable to subshells. The set command can be used to assign values to variables, but it does not export them. The env command can be used to run a command in a modified environment, but it does not change the environment of the current shell. References:

[LPI Linux Essentials - Topic 105: Shells, Scripting and Data Management]

[LPI Linux Professional - Exam 102 Objectives - Topic 105: Shells and Shell Scripting]

What is a Subshell? - Linux Bash Shell Scripting Tutorial Wiki - nixCraft

What is Subshell in Linux? [Explained]

The #! followed by a file path is called a shebang or a hashbang. It is a special notation that tells the operating system which interpreter to use to execute the script. For example, if the first line of a script is #!/bin/bash, it means that the script will be run by the Bash shell, which is located at /bin/bash. Similarly, if the first line of a script is #!/usr/bin/python3, it means that the script will be run by the Python 3 interpreter, which is located at /usr/bin/python3. The shebang must be the very first line of the script, and it must start with #! without any spaces. The file path after the #! must be an absolute path, not a relative path or a symbolic link. The shebang allows the script to be executed as a standalone program, without specifying the interpreter explicitly. For example, if a script named hello.sh has a shebang of #!/bin/bash, and it has the executable permission, it can be run as ./hello.sh instead of bash hello.sh. The shebang also allows the script to be associated with a specific interpreter, regardless of the default interpreter of the system or the user. For example, if a script named hello.py has a shebang of #!/usr/bin/python3, it will always be run by Python 3, even if the system or the user has Python 2 as the default Python interpreter. The shebang is not a comment, although it looks like one. It is a special instruction that is only recognized by the operating system when the script is executed. It is ignored by the interpreter when the script is read. Therefore, the shebang does not indicate that the file at that location was used to make the script, or that the script provides identical functionality as the file at that location, or that the script will self-extract into a file at that location. The correct answer is that the program at that location will be used to process the script. You can learn more about the shebang here1 and here2. References:

1 2

The /etc/skel directory is used to keep a sample copy of files and directories for when a new user has a home directory created. The /etc/skel directory contains files and directories that are automatically copied over to a new user’s home directory when such user is created by the useradd or adduser command. The /etc/skel directory allows the system administrator to create a standard environment for all new users on the system. For example, the /etc/skel directory may contain a default .bashrc file that sets some aliases and environment variables for the new user, or a default .profile file that executes some commands at login. The /etc/skel directory may also contain subdirectories such as .ssh or .config that store configuration files for various applications or services. The name /etc/skel comes from the word “skeleton”, as it provides a basic structure for the new user’s home directory. References:

[Linux User Administration]

[Linux Directory Structure]

The /etc/skel directory contains files and directories that are used as a template for creating a new user’s home directory. The useradd command uses the -m (or --create-home) option to create the user home directory as /home/username and copy the files from /etc/skel to it. The files in /etc/skel are typically initialization files such as .bashrc, .profile, and .bash_logout that set the user’s environment variables, aliases, and other preferences. The system administrator can customize the /etc/skel directory to provide a consistent and convenient initial setup for new users. References: 

https://www.howtouselinux.com/post/create-new-user-with-home-directory-in-linux

https://linuxize.com/post/how-to-create-users-in-linux-using-the-useradd-command/