010-160 Exam Dumps - LPI Linux Essentials Questions and Answers

 The correct command to set the variable USERNAME to the value bob is USERNAME=bob. This command assigns the string bob to the variable name USERNAME, using the equal sign (=) as the assignment operator. There is no space around the equal sign, and the variable name and value are case-sensitive. This command sets a shell variable, which is only valid in the current shell session. To make the variable an environment variable, which can be inherited by child processes and subshells, you need to use the export command, such as export USERNAME=bob. The other commands are not valid for setting variables in Linux. The set command is used to set orunset shell options and positional parameters, not variables. The $ sign is used to reference the value of a variable, not to assign it. The == sign is used for comparison, not assignment. The var keyword is not used in Linux, but in some other programming languages. The <= sign is used for redirection, not assignment. References:

• Linux Essentials - Linux Professional Institute (LPI)
• How to Set and List Environment Variables in Linux | Linuxize

CentOS is a Linux distribution that is based on the source code of Red Hat Enterprise Linux (RHEL). It is a free and open-source community-supported OS that provides an enterprise-level computing platform. CentOS is fully compatible with RHEL and can run the same applications and packages. Therefore, CentOS allows the team members to apply as much of their Red Hat Enterprise Linux knowledge as possible for their hobby project. References:

• Linux Essentials Version 1.6 Objectives1, Topic 1.1: Linux Evolution and Popular Operating Systems, Subtopic: Linux Distributions
• Linux Essentials Version 1.6 Exam Preparation Guide2, Section 1.1: Linux Evolution and Popular Operating Systems, Page 7
• CentOS Website3, About CentOS Linux
• Red Hat Enterprise Linux derivatives - Wikipedia4

The distribution’s package repository is the preferred source for the installation of new applications in a Linux based operating system. A package repository is a collection of software packages that are maintained by the distribution and can be easily installed, updated, or removed using a package manager. Package repositories offer several advantages, such as:

• They ensure compatibility and stability with the system and other packages.
• They provide security updates and bug fixes for the packages.
• They reduce the risk of malware or corrupted files.
• They simplify the dependency management and configuration of the packages.

The other sources are not preferred because they may not offer these benefits and may cause problems with the system. The vendor’s version management system, the vendor’s website, or a CD-ROM disk may contain packages that are not compatible with the distribution or may conflict with other packages. A retail store may not have the latest or the most suitable packages for the system. References:

• Linux Essentials - Linux Professional Institute (LPI), section 1.3 Installing, Updating and Removing Software Packages
• LPI Linux Essentials Study Guide: Exam 010 v1.6, 3rd Edition, chapter 4 Working on the Command Line, section 4.2 Managing Software
• Table of Contents - Linux Professional Institute Certification Programs, section 1.3 Installing, Updating and Removing Software Packages

 Reverse DNS lookups query DNS servers for a PTR (pointer) record; if the server does not have a PTR record, it cannot resolve a reverse lookup. PTR records store IP addresses with their segments reversed, and they append “.in-addr.arpa” to that. For example, if a domain has an IP address of 192.0.2.1, the PTR record will store the domain’s information under 1.2.0.192.in-addr.arpa. In IPv6, the latest version of the Internet Protocol, PTR records are stored within the “.ip6.arpa” domain instead of ".in-addr.arpa."1 Therefore, the name of the IP address 198.51.100.165 is stored in the PTR record for 165.100.51.198.in-addr.arpa. References: 1: Reverse DNS lookup - Wikipedia 1

The last command in Linux is used to display the list of all the users logged in and out since the file /var/log/wtmp was created1. The output of the last command shows the username, the terminal, the IP address, the login time and date, and the duration of the session for each record2. The option E is the only one that matches this format. Theother options are not related to the last command. Option A shows a list of commands executed by a user. Option B shows the password change information for a user. Option C shows the last login information for a user. Option D shows the mount information for a filesystem. References:

• Linux Essentials Version 1.6 Objectives3, Topic 1.4: Command Line Basics, Subtopic: Basic Shell Commands
• Linux last Command Tutorial for Beginners (8 Examples)4
• Linux Essentials Version 1.6 Exam Preparation Guide, Section 1.4: Command Line Basics, Page 16

The -R parameter of the ls command prints a recursive listing of a directory’s content, meaning that it will list not only the files and directories in the current directory, but also the files and directories in all the subdirectories12. For example, if you have a directory structure like this:

/home/user/├──dir1│├──file1│└──file2└──dir2├──file3└──file4

You can use the command ls -R /home/user/ to list all the files and directories recursively, and the output will look like this:

/home/user/: dir1 dir2

/home/user/dir1: file1 file2

/home/user/dir2: file3 file4

The -R parameter is also known as the --recursive option, which is the long form of the same parameter12. You can use either -R or --recursive to achieve the same result.

References:

• Use ls Command Recursively - Linux Handbook
• How to List Files Recursively in Linux command line

 Linux hardware drivers are software components that enable the Linux kernel to communicate with various devices, such as keyboards, mice, printers, scanners, network cards, etc. Drivers are either compiled into the Linux kernel or are loaded as kernel modules. Kernel modules are pieces of code that can be loaded and unloaded into the kernelon demand. They extend the functionality of the kernel without requiring to rebuild or reboot the system. Drivers that are compiled into the kernel are always available, but they increase the size and complexity of the kernel. Drivers that are loaded as kernel modules are only available when needed, but they require a matching version of the kernel and the module. Linux supports a large number of hardware devices, thanks to the efforts of the open source community and some vendors who provide drivers for their products. However, some devices may not have a driver available for Linux, or may require a proprietary driver that is not included in the Linux distribution. In such cases, the user may need to install the driver manually from the vendor’s website or from a third-party repository. References:

• Linux Essentials - Linux Professional Institute (LPI), section 2.2.1
• LPI Linux Essentials Study Guide: Exam 010 v1.6, 3rd Edition, chapter 3, page 67.

The /etc/passwd file is a plain text-based database that contains information for all user accounts on the system. It is owned by root and has 644 permissions. The file can only be modified by root or users with sudo privileges and readable by all system users. Each line of the /etc/passwd file contains seven comma-separated fields, representing a user account. The fields are as follows:

• Username: The string you type when you log into the system. Each username must be a unique string on the machine. The maximum length of the username is restricted to 32 characters.
• Password: In older Linux systems, the user’s encrypted password was stored in the /etc/passwd file. On most modern systems, this field is set to x, and the user password is stored in the /etc/shadow file.
• User ID (UID): The user identifier is a number assigned to each user by the operating system to refer to a user. It is used by the kernel to check for the user privileges and grant access to system resources. The UID 0 is reserved for the root user and cannot be assigned to any other user.
• Group ID (GID): The user’s group identifier number, referring to the user’s primary group. When a user creates a file, the file’s group is set to this group. Typically, the name of the group is the same as the name of the user. User’s secondary groups are listed in the /etc/group file.
• User ID Info (GECOS): This is a comment field. This field contains a list of comma-separated values with the following information: User’s full name or the application name, Room number, Work phone number, Home phone number, Other contact information.
• Home directory: The absolute path to the user’s home directory. It contains the user’s files and configurations. By default, the user home directories are named after the name of the user and created under the /home directory.
• Login shell: The absolute path to the user’s login shell. This is the shell that is started when the user logs into the system. On most Linux distributions, the default login shell is Bash.

Therefore, the correct answers are B, C, and E. The user’s storage space limit (A) is not stored in the /etc/passwd file, but in the /etc/quota file. The encrypted password (D) is not stored in the /etc/passwd file, but in the /etc/shadow file. References:

• Linux Essentials Topic 104: The Linux Operating System, section 104.4: Runlevels and Boot Targets.
• Linux Essentials Topic 106: Security and File Permissions, section 106.1: Basic security and identifying user types.
• Linux Essentials Topic 106: Security and File Permissions, section 106.2: Creating users and groups.
• Understanding the /etc/passwd File | Linuxize
• Understanding the /etc/passwd File - GeeksforGeeks
• passwd(5) - Linux manual page - man7.org
• Understanding /etc/passwd file in Linux - DEV Community

The zip command is used to create compressed archive files that can contain one or more files or directories. The zip command takes the name of the archive file as the first argument, followed by the names of the files or directories to be included in the archive. You can also use wildcards to match multiple files or directories with a common pattern. For example, the command zip poems.zip *.txt will create the ZIP archive poems.zip containing all files in the current directory whose names end in .txt. The other commands are either invalid or do not perform the desired operation. The command zip *.txt > poems.zip will try to create an archive for each file ending in .txt and redirect the output to poems.zip, which is not a valid archive file. The command zcat *.txt poems.zip will try to decompress and concatenate the contents of the files ending in .txt and poems.zip, which is not a valid ZIP file. The command zip cfz poems.zip *.txt will fail because the options c, f, and z are not valid for the zip command. The command cat *.txt | zip poems.zip will try to read the contents of the files ending in .txt from the standard input and create an archive named poems.zip, but this will not preserve the file names or attributes of the original files. References:

• Linux Essentials - Linux Professional Institute (LPI), section 3.1.1
• 3.1 Archiving Files on the Command Line - Linux Professional Institute Certification Programs, slide

 A private web browser window is a mode of browsing that prevents the browser from saving your browsing history, cookies, and other site data, or information entered in forms. However, it does not prevent websites, your employer or school, or your internet service provider from tracking your online activity. The main differences between a private web browser window and a regular web browser window are:

• Private web browser windows do not store cookies persistently. Cookies are small files that websites use to store information on your device, such as your preferences, login status, or tracking data. In a regular web browser window, cookies are stored until they expire or you delete them. In a private web browser window, cookies are deleted when you close all private windows.
• Private web browser windows do not keep records in the browser history. The browser history is a list of web pages that you have visited in the past. In a regular web browser window, the browser history is saved and can be accessed by anyone who uses the same device or profile. In a private web browser window, the browser history is not saved and cannot be viewed by anyone.
• Private web browser windows do not send regular stored cookies. When you visit a website in a regular web browser window, the browser sends any cookies that are stored for that website. This allows the website to recognize you and provide personalized content or services. When you visit a website in a private web browser window, the browser does not send any cookies that are stored in regular windows. This prevents the website from identifying you or linking your activity across different sessions.

References: Browse in private - Computer - Google Chrome Help, Browse InPrivate in Microsoft Edge - Microsoft Support, Private Browsing: What Is It and How to Use It | Edge Learning Center