010-160 Linux Essentials Certificate Exam - version 1.6 Question and Answers

To remove a directory, you need to use a command that can delete directories, not just files. The rm command can only remove files by default, unless you use the -r option, which stands for recursive. This option tells rm to delete the directory and all of its contents, including subdirectories and files. The rmdir command can also remove directories, but only if they are empty. If the directory contains any files or subdirectories, rmdir will fail and display an error message. Therefore, the correct commands to remove Downloads, assuming it is empty, are rmdir Downloads and rm -r Downloads. The other commands are either invalid or do not work on directories. References:

• Linux Essentials - Linux Professional Institute (LPI), section 2.3.1
• LPI Linux Essentials Study Guide: Exam 010 v1.6, 3rd Edition, chapter 4, page 93.

When a user account is deleted, the files owned by that user are not automatically deleted from the file system, unless they are in the user’s home directory. The files residing outside the home directory will remain unchanged, but they will have an invalid owner. The owner of a file is identified by a numeric user ID (UID), which is mapped to a user name by the /etc/passwd file. When a user is deleted, the corresponding entry in the /etc/passwd file is removed, but the UID of the file is not changed. Therefore, when listing the file’s details, the UID of the former owner is shown instead of the user name. For example, if the user alice with UID 1001 is deleted, and she owns a file named report.txt in the /tmp directory, the output of ls -l /tmp/report.txt will look something like this:

-rw-r–r-- 1 1001 users 1024 Nov 20 14:11 /tmp/report.txt

The user root is not set as the new owner of the file, nor is the file moved to /lost+found or removed from the file system. The /lost+found directory is used to store files that are recovered from a corrupted file system after running the fsck command, not from deleted user accounts. The file system check does not affect the ownership or permissions of the files, unless there is a serious inconsistency that needs to be fixed. References:

• Linux Essentials - Linux Professional Institute (LPI), section 5.2.1
• 5.2 Lesson 1 - Linux Professional Institute Certification Programs, slide 6.

 A bus is a communication system that transfers data between components inside a computer or between computers. There are different types of buses that serve different purposes. The RAM bus connects the CPU with the main memory, the NUMA bus connects multiple processors in a multiprocessor system, the CPU bus connects the CPU with other components on the motherboard, and the Auto bus is a fictional bus that can transform into a robot. The SATA bus is the correct answer because it is a type of bus that can connect hard disk drives with the motherboard. SATA stands for Serial Advanced Technology Attachment and it is a standard interface for connecting storage devices such as hard disk drives, solid state drives, and optical drives. SATA offers faster data transfer rates, lower power consumption, and improved cable management compared to older interfaces such as IDE and SCSI. References: : [Bus (computing)] : [Transformers: Robots in Disguise (2015 TV series)] : [Serial ATA]3) : [SATA vs. IDE: What’s the Difference?]

 The dmesg command is used to display the messages from the kernel that are stored in a ring buffer. A ring buffer is a fixed-size data structure that overwrites the oldest entries when it is full. Therefore, the dmesg command might not display older information because it was overwritten by newer information. The dmesg command is useful for troubleshooting system issues and checking hardware information. The dmesg command is not used to trace the execution of a command, send messages to user sessions, or output the system journal. Those functions are performed by other commands such as strace, write, and journalctl respectively. References: : [dmesg] : [Ring buffer] : [strace] : [write (Unix)] : [journalctl]4)

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

 The sort command is used to sort the lines of a text file or the output of another command in alphabetical, numerical, or other order. The sort command has the following syntax: sort [options] [file…]. The file argument is the name of one or more files to be sorted. If no file is given, the sort command reads from the standard input, which is usually the keyboard or the output of another command.

The | (pipe) symbol is used to connect the output of one command to the input of another command. This allows the creation of pipelines of commands that process data sequentially. The pipe symbol has the following syntax: command1 | command2. The command1 argument is the name of the first command, whose output is sent to the input of the second command. The command2 argument is the name of the second command, which receives the output of the first command as its input.

Therefore, the command export-logs | sort sorts the output of the export-logs command in alphabetical order. The export-logs command is assumed to be a custom command that exports some logs to the standard output. The sort command receives the output of the export-logs command as its input and sorts it according to the default criteria, which is the first character of each line. The sorted output is then displayed on the screen or can be redirected to a file or another command.

The other options in the question are incorrect because they use the wrong symbols to connect the commands. The < (input redirection) symbol is used to read the input of a command from a file instead of the keyboard. The > (output redirection) symbol is used to write the output of a command to a file instead of the screen. The & (background) symbol is used to run a command in the background, which means the command does not wait for user input and allows the user to run other commands simultaneously. The <> (bidirectional redirection) symbol is used to read and write the input and output of a command from and to the same file. None of these symbols can be used to sort the output of the export-logs command. References:

• Linux Essentials Version 1.6 Objectives: 3.2. Searching and Extracting Data from Files1
• Linux Essentials Version 1.6 Exam Study Resources: Linux Essentials Manual - Chapter 9. The Power of the Command Line - 9.2. Searching and Extracting Data from Files - 9.2.1. The sort Command2
• Linux Essentials Version 1.6 Exam Study Resources: Linux Essentials Manual - Chapter 9. The Power of the Command Line - 9.3. Turning Commands into a Script - 9.3.1. Pipes and Redirection2
• Linux Essentials Version 1.6 Exam Study Resources: Linux Essentials Manual - Appendix A. Answers to the Exercises - Chapter 9. The Power of the Command Line - 9.2. Searching and Extracting Data from Files - Exercise 9.2.12
• Linux Essentials Version 1.6 Exam Study Resources: Linux Essentials Manual - Appendix A. Answers to the Exercises - Chapter 9. The Power of the Command Line - 9.3. Turning Commands into a Script - Exercise 9.3.12

Most commands on Linux can display information on their usage by running the command with the option -h or --help. This option shows a brief summary of the command syntax, options, arguments, and examples. For example, running ls -h or ls --help will display the usage information for the ls command, which lists files and directories. The -h or --help option is a standard convention for most Linux commands, and it is useful for learning how to use a command or checking its available options. However, some commands may not support this option, or may use a different option to display usage information. In that case, you can use the man command to access the manual page for the command, which provides more detailed information on the command usage, description, options, arguments, examples, and references. For example, running man ls will display the manual page for the ls command. The man command is one of the applications covered in the Linux Essentials certification program from the Linux Professional Institute (LPI). References:

• Linux Essentials - Linux Professional Institute (LPI)
• Linux Commands Cheat Sheet: Beginner to Advanced - GeeksforGeeks

 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

 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

The command pwd stands for “print working directory”. It will print the absolute path of the current working directory to the terminal. For example, if we are currently in the /home/user/directory, it will print out that exact path1. The pwd command is useful for finding out where we are in the file system hierarchy and for verifying the location of files and directories2.

The other options are not commands that show the absolute path to the current working directory. The who command shows the users who are currently logged in to the system3. The cd … command changes the current working directory to the parent directory of the current one2. The ls -l command lists the files and directories in the current working directory in a long format, which shows the permissions, ownership, size, date, and name of each file and directory2. The cd ~/home command changes the current working directory to the /home directory under the user’s home directory, which may or may not exist2. References:

• Linux Essentials Exam Objectives, Version 1.6, Topic 103.1, Weight 2
• Linux Essentials Certification Guide, Chapter 3, Page 51-52
• How to Get the current directory in Linux - howtouselinux
• How To Find The Absolute Path Of A File Or Directory In Linux - systranbox

A Linux distribution is a collection of software that is based on the Linux kernel and can be installed on a computer or a device to create a functional operating system. A Linux distribution typically includes the Linux kernel, a set of system utilities and libraries, a graphical user interface (GUI), a package manager, and various applications and services. A Linux distribution may also include additional software or features that are specific to the distribution’s goals, target audience, or philosophy. For example, some Linux distributions are designed for desktop users, while others are optimized for servers, embedded systems, or security. Some Linux distributions are based on other Linux distributions, while others are developed independently. Some Linux distributions are free and open source, while others are proprietary or commercial. Some Linux distributions are popular and widely used, while others are niche or experimental. Some examples of Linux distributions are Ubuntu, Fedora, Debian, Mint, Arch, and Red Hat. References:

• Linux Essentials Topic 101: System Architecture, section 101.1: Determine and configure hardware settings.
• Linux Essentials Topic 102: Linux Installation and Package Management, section 102.1: Design hard disk layout.
• Linux Essentials Topic 103: GNU and Unix Commands, section 103.1: Work on the command line.
• Linux Essentials Topic 104: The Linux Operating System, section 104.1: Boot the system.
• Linux Essentials Topic 105: The Power of the Command Line, section 105.1: Use text streams and filters.
• Linux Essentials Topic 106: Security and File Permissions, section 106.3: Modify file and directory permissions.
• What is a Linux distribution? - Linux.com
• Linux distribution - Wikipedia
• Best Linux Distributions For Everyone in 2023 - It’s FOSS

The backslash character () is used to escape the meaning of the next character in a command line. This means that the next character is treated as a literal character, not as a special character. For example, if you want to use a space in a file name, you can use a backslash before the space to prevent the shell from interpreting it as a separator. Similarly, if you want to split a long command line across multiple lines, you can use a backslash at the end of each line to tell the shell that the command is not finished yet. The shell will ignore the newline character and continue reading the next line as part of the same command. For example, you can write:

ls -l/home/user/Documents

instead of:

ls -l /home/user/Documents

Both commands will produce the same output, but the first one is easier to read and type. References:

• Linux Essentials - Linux Professional Institute (LPI), section 2.1.2
• 2.1 Command Line Basics - Linux Professional Institute Certification Programs, slide 7.

DHCP stands for Dynamic Host Configuration Protocol. It is a protocol that provides quick, automatic, and central management for the distribution of IP addresses within a network. It also configures other network information, such as the subnet mask, default gateway, and DNS server information, on the device1. DHCP uses a client/server architecture, where a DHCP server issues unique IP addresses and automatically configures the devices that request them2. DHCP allows devices to move freely from one network to another and receive an IP address automatically, which is helpful with mobile devices1.

The other options are not protocols used for automatic IP address configuration. NFS stands for Network File System, which is a protocol that allows a user to access and modify files over a network as if they were on their own computer. LDAP stands for Lightweight Directory Access Protocol, which is a protocol that provides access to a centralized directory service that stores information about users, groups, computers, and other resources on a network. SMTP stands for Simple Mail Transfer Protocol, which is a protocol that enables the sending and receiving of email messages over a network. DNS stands for Domain Name System, which is a protocol that translates domain names into IP addresses and vice versa. References:

• Linux Essentials Exam Objectives, Version 1.6, Topic 105.1, Weight 4
• What Is DHCP? (Dynamic Host Configuration Protocol) - Lifewire
• Dynamic Host Configuration Protocol (DHCP) | Microsoft Learn
• Dynamic Host Configuration Protocol - Wikipedia
• How does AutoIP work? - Barix
• [Network File System - Wikipedia]
• [Lightweight Directory Access Protocol - Wikipedia]
• [Simple Mail Transfer Protocol - Wikipedia]
• [Domain Name System - Wikipedia]

 The correct commands to output the content of the file Texts 2.txt are A and E. These commands use the cat command, which stands for concatenate, to display the content of one or more files. The cat command can take one or more filenames as arguments and print their content to the standard output (usually the terminal screen)12. The commands A and E use different ways to deal with the space character in the filename. The space character is a special character in Linux that separates words and commands. To prevent the shell from interpreting the space as a word separator, the commands A and E use either of the following methods34:

• Option A uses single quotes (') around the filename to preserve the literal value of the space character. This tells the shell to treat the filename as a single argument and pass it to the cat command. For example: cat ‘Texts 2.txt’
• Option E uses a backslash () before the space character to escape its special meaning. This tells the shell to ignore the space as a word separator and treat it as part of the filename. For example: cat Texts\ 2.txt

The other options are incorrect because they use different syntax that do not output the content of the file. For example:

• Option B uses a double dash (–) before the filename to indicate the end of options. This is usually used to prevent the shell from interpreting a filename that starts with a dash (-) as an option. However, in this case, the filename does not start with a dash, so the double dash is unnecessary and will cause the command to fail. For example: cat – Texts 2.txt
• Option C uses vertical bars (|) around the filename to indicate a pipe. A pipe is a way of connecting the output of one command to the input of another command. However, in this case, there is no command before or after the pipe, so the pipe is meaningless and will cause the command to fail. For example: cat |Texts 2.txt|
• Option D uses single quotes (') and a backslash () together around the filename. This is redundant and will cause the command to fail. The single quotes already preserve the literal value of the space character, so the backslash is not needed. Moreover, the backslash inside the single quotes will be treated as part of the filename, not as an escape character. For example: cat ‘Texts\ 2.txt’

References: 1: How to Use Linux Cat Command (With Examples) - phoenixNAP 2: Cat command in Linux with examples - GeeksforGeeks 3: How to escape spaces in path during scp copy in Linux? - Stack Overflow 4: How to handle spaces in file names when using xargs on find results? - Ask Ubuntu

The commands man ls and info ls are used to get information on the proper use of ls. The man command displays the manual page for a given command, which contains a description, synopsis, options, examples, and other details. The info command displays the info page for a given command, which is similar to the manual page but may have more information and hyperlinks. The option ls, usage ls, and manual ls commands are not valid commands in Linux and will result in an error message. References:

• Linux Essentials Exam Objectives, Version 1.6, Topic 103.1, Weight 2
• Linux Essentials Certification Guide, Chapter 3, Page 51-52
• Ls Command in Linux (List Files and Directories) | Linuxize

The main difference between hard disk drives (HDDs) and solid state drives (SSDs) is the way they store and access data. HDDs use a spinning disk (platter) and a moving head to read and write data, while SSDs use flash memory chips that have no moving parts. This makes SSDs faster, quieter, and more durable than HDDs, but also more expensive and less spacious. HDDs and SSDs are both I/O devices that can be used to boot the system and store data, but they have different advantages and disadvantages depending on the use case. References:

• Difference between Hard Disk Drive (HDD) and Solid State Drive (SSD)
• Hard Disk Drive (HDD) vs. Solid State Drive (SSD): What’s the Difference?
• How to Check Whether Your Disk Is an SSD or HDD on Linux

The passwd command in Linux is used to change the password of a user account. A normal user can run passwd to change their own password, and a system administrator (the superuser) can use passwd to change another user’s password, or define how that account’s password can beused or changed1. The passwd command can also be used to lock or unlock a user account. Locking a user account means disabling the user’s ability to log in to the system, while unlocking a user account means restoring the user’s ability to log in. To lock a user account, the passwd command can be used with the -l option, followed by the username. To unlock a user account, the passwd command can be used with the -u option, followed by the username12. The passwd command cannot be used to change a user’s username, create a new user account, or create a new user group. These tasks require different commands, such as usermod, useradd, orgroupadd345. References: 1: Linux Passwd Command Help and Examples 2: Passwd command in Linux: 8 Practical Examples 3: usermod(8) - Linux man page 4: useradd(8) - Linux man page 5: groupadd(8) - Linux man page

 The DNS record types that hold an IP address are the A and AAAA records. These records are used to map a domain name to an IP address of the host, which is necessary for establishing a connection between a client and a server. The A record holds a 32-bit IPv4 address, while the AAAA record holds a 128-bit IPv6 address. For example, the A record for www.example.com could be:

www.example.com. IN A 192.0.2.1

This means that the domain name www.example.com resolves to the IPv4 address 192.0.2.1. Similarly, the AAAA record for www.example.com could be:

www.example.com. IN AAAA 2001:db8::1

This means that the domain name www.example.com resolves to the IPv6 address 2001:db8::1.

The other options are incorrect because:

• NS records are used to specify the authoritative name servers for a domain. They do not hold an IP address, but a domain name of the name server. For example, the NS record for example.com could be:

example.com. IN NS ns1.example.com.

This means that the name server ns1.example.com is authoritative for the domain example.com.

• MX records are used to specify the mail exchange servers for a domain. They do not hold an IP address, but a domain name of the mail server and a preference value. For example, the MX record for example.com could be:

example.com. IN MX 10 mail.example.com.

This means that the mail server mail.example.com has a preference value of 10 for receiving email for the domain example.com.

• CNAME records are used to create an alias for a domain name. They do not hold an IP address, but another domain name that the alias points to. For example, the CNAME record for www.example.com could be:

www.example.com. IN CNAME example.com.

This means that the domain name www.example.com is an alias for the domain name example.com.

References:

• DNS Record Types: Defined and Explained - Site24x7
• List of DNS record types - Wikipedia

RPM stands for RPM Package Manager (formerly known as Red Hat Package Manager), which is a powerful, command-line package management tool developed for the Red Hat operating system. It is now used as a core component in many Linux distributions such as CentOS, Fedora, Oracle Linux, openSUSE and Mageia1. RPM can install, uninstall,and query individual software packages, but it cannot manage dependency resolution like YUM2. YUM is another package management tool that is based on RPM and can handle dependencies automatically. YUM is the primary package management tool for installing, updating, removing, and managing software packages in Red Hat Enterprise Linux2. Therefore, the correct answer is B. rpm, as it is the underlying package management tool used in Red Hat-based Linux systems. References:

• Linux package management with YUM and RPM | Enable Sysadmin
• Chapter 13. Package Management Tool Red Hat Enterprise Linux 5 | Red Hat Customer Portal
• Difference Between YUM and RPM | 2DayGeek

The correct command to change the ownership of the file doku.odt to a new owner named tux is chown tux doku.odt. This command uses the chown command, which stands for change owner, followed by the name of the new owner and the name of the file as arguments. The chown command allows you to change the user and/or group ownership of a given file, directory, or symbolic link12. The other options are incorrect because they use different commands or syntax that do not change the ownership of the file. For example:

• Option A uses the chmod command, which stands for change mode, and is used to change the permissions of files and directories, not the ownership3.
• Option B uses the newuser command, which is used to create a new user account, not to change the ownership of a file4.
• Option D uses the transfer command, which is not a valid Linux command.
• Option E uses the passwd command, which is used to change the password of a user account, not the ownership of a file5.

References: 1: Chown Command in Linux (File Ownership) | Linuxize 2: chown command in Linux with Examples - GeeksforGeeks 3: Chmod Command in Linux (File Permissions) | Linuxize 4: newusers(8) - Linux man page 5: passwd(1) - Linux man page

These are the three most common service models offered by public cloud providers12. They differ in the level of abstraction and control they provide to the customers.

• Platform as a Service (PaaS) is a service model where the public cloud provider offers a ready-to-use platform for developing, testing, and deploying applications. The provider manages the underlying infrastructure, such as servers, storage, network, and operating system, while the customer only needs to focus on the application code andconfiguration. Examples of PaaS include Google App Engine, IBM Cloud Foundry, and Microsoft Azure App Service12.
• Infrastructure as a Service (IaaS) is a service model where the public cloud provider offers access to fundamental compute, network, and storage resources on demand over the public Internet or through dedicated connections. The provider manages the physical hardware and virtualization layer, while the customer has full control over the configuration and management of the virtual machines, operating system, and applications. Examples of IaaS include Google Compute Engine, IBM Cloud Virtual Servers, and Microsoft Azure Virtual Machines12.
• Software as a Service (SaaS) is a service model where the public cloud provider offers ready-to-use software applications that run on the provider’s infrastructure and are accessible through a web browser or a mobile app. The provider manages the entire software stack, including the infrastructure, platform, and application, while the customer only needs to pay for the usage or subscription of the service. Examples of SaaS include Google Workspace, IBM Watson, and Microsoft Office 36512.

References:

• What is Public Cloud | IBM
• What Is a Public Cloud? | Google Cloud