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

 The correct command to copy the contents of the directory /etc/, including all sub-directories, to /root/ is cp -r /etc/* /root. This command uses the cp command, which stands for copy, and is used to copy files and directories on Linux and Unix systems. The command also uses the following options and arguments123:

• The -r option, which stands for recursive, and tells cp to copy all files and sub-directories of the source directory. Alternatively, the -R option can be used, which has the same effect as -r.
• The /etc/* argument, which specifies the source directory and all its contents. The asterisk (*) is a wildcard character that matches any file or directory name. This argument tells cp to copy everything inside the /etc/ directory, but not the directory itself.
• The /root argument, which specifies the destination directory. This argument tells cp to copy the source files and sub-directories to the /root/ directory.

The other options are incorrect because they use different commands or syntax that do not copy the contents of the directory /etc/, including all sub-directories, to /root/. For example:

• Option A uses the copy command, which is not a valid Linux command. The correct command is cp.
• Option C uses the -v option, which stands for verbose, and tells cp to print verbose output. This option does not affect the copying process, but only the output. It also does not include the -r or -R option, which is necessary to copy the sub-directories.
• Option D uses the rcp command, which stands for remote copy, and is used to copy files between different hosts on a network. This command is not relevant for copying files on the same host.
• Option E uses the -R option, which is correct, but also uses the . argument, which is incorrect. The dot (.) is a special character that matches any single character. This argument tells cp to copy only the files and directories that have a dot in their name, which may exclude some files and directories that do not have a dot.

References: 1: Cp Command in Linux (Copy Files) | Linuxize 2: cp command in Linux with examples - GeeksforGeeks 3: How to Copy Files and Directories in the Linux Terminal

 A typical shell script is a text file that contains a series of commands or instructions that can be executed by a shell interpreter. A shell script usually has the executable permission bit set, which means that it can be run as a program by the user or another program. A shell script also starts with the two character sequence #!, which is called a shebang or a hashbang. This sequence tells the operating system which shell interpreter to use to run the script. For example, #!/bin/bash indicates that the script should be run by the bash shell. References:

• Linux Essentials - Linux Professional Institute (LPI) 1
• Linux Essentials - Linux Professional Institute Certification Programs 2

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

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

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

Section: (none)

 The correct device name that represents a hard disk partition is /dev/sda2. This device name follows the Linux convention for naming hard disk devices and partitions. According to this convention123:

• The first part of the device name indicates the type of the device. For example, /dev/hd* for IDE drives, /dev/sd* for SCSI, SATA, USB, or eSATA drives, /dev/nvme* for NVMe drives, etc.
• The second part of the device name indicates the order of the device as detected by the system. For example, /dev/sda is the first serial drive, /dev/sdb is the second serial drive, and so on.
• The third part of the device name indicates the number of the partition on the device. For example, /dev/sda1 is the first partition on the first serial drive, /dev/sda2 is the second partition on the first serial drive, and so on.

Therefore, /dev/sda2 means the second partition on the first serial drive, which is a valid hard disk partition. The other options are not valid hard disk partitions, because they do not follow the Linux convention. For example:

• /dev/ttyS0 is a serial port device, not a hard disk device4.
• /dev/sata0 is not a valid device name, because it does not specify the partition number. It should be something like /dev/sata0p1 or /dev/sata0p2, etc.
• /dev/part0 is not a valid device name, because it does not specify the device type or the partition number. It should be something like /dev/sdXp0 or /dev/hdXp0, etc.
• /dev/sda/p2 is not a valid device name, because it uses a slash (/) instead of a number to indicate the partition. It should be something like /dev/sda2 or /dev/sda3, etc.

References: 1: Hard drive/device partition naming convention in Linux - Unix & Linux Stack Exchange 2: Hard drive partition naming convention in Linux - Ask Ubuntu 3: C.4. Device Names in Linux - Debian 4: What is /dev/ttyS0? - Quora

Explanation

A symbolic link, also known as a symlink or soft link, is a special type of file that points to another file or directory by its name. A symbolic link can point to a file or directory on the same or different file system, as long as the target is accessible. For example, you can create a symbolic link to a file on a USB drive or a network share, as long as the device is mounted or the connection is established. However, if the target of the symbolic link is moved, renamed, or deleted, the link becomes broken and does not work. To create a symbolic link, you can use the ln command with the -s or --symbolic option, followed by the target name and the link name. For example, ln -s /mnt/usb/file.txt link.txt creates a symbolic link named link.txt that points to the file.txt on the USB drive mounted at /mnt/usb.

The other options are not true about links in a Linux file system. A symbolic link can point to a directory as well as a file. A hard link, which is a direct reference to the same data as another file, can only point to a file and not a directory. A hard link cannot span across different file systems, because it depends on the inode number, which is unique within a file system. When the target of the symbolic link is moved, the link is not automatically updated, but becomes broken. Any user can create hard links, as long as they have the permission to read and write the target file and the link directory.

References:

• Linux Essentials - Linux Professional Institute (LPI)
• Ln Command in Linux (Create Symbolic Links) | Linuxize

The correct statement about Free Software is that it may be modified by anyone using it. This is one of the four essential freedoms of Free Software, which are: the freedom to run the program as you wish, for any purpose; the freedom to study how the program works, and change it so it does your computing as you wish; the freedom to redistribute copies so you can help your neighbor; and the freedom to distribute copies of your modified versions to others1. Access to the source code is a precondition for these freedoms1.

The other statements are false for the following reasons:

• Free Software is not developed by volunteers only. It can be developed by anyone, including individuals, companies, organizations, or communities. Some Free Software developers are paid for their work, while others do it as a hobby or for social benefit1.
• Free Software does not have to be available free of charge. It can be sold or given away for any price. The term “free” refers to the users’ freedom, not the price of the software1. However, Free Software users have the freedom to redistribute copies, so they can obtain the software at no charge from someone who has a copy1.
• Free Software does not only run on Linux. It can run on any operating system that supports it, such as Windows, MacOS, BSD, or Android. Linux is an example of a Free Software operating system, but not the only one1.
• Free Software is not only distributed as a compiled binary. It can also be distributed as source code, or both. In fact, Free Software must provide access to the source code, otherwise the users cannot study or modify the software1.

References:

• What is Free Software? - GNU Project - Free Software Foundation

 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 /proc/ directory is a virtual file system that contains information about the system and the processes running on it. It is not a conventional file system that stores files on a disk, but rather a dynamic view of the kernel’s data structures. One of the features of the /proc/ directory is that it contains one subdirectory for each process running on the system, which is named after the process ID (PID). For example, the subdirectory /proc/1/ contains information about the process with PID 1, which is usually the init process. The process subdirectories contain various files that provide information about the process, such as its status, memory usage, open files, environment variables, command line arguments, and more. The /proc/ directory also contains a symbolic link called ‘self’, whichpoints to the process that is accessing the /proc/ file system. Therefore, the correct answer is D. One directory per running process.

The other options are incorrect because:

• A. One directory per installed program. This is not true, as the /proc/ directory does not contain information about installed programs, but only about running processes. Installed programs are usually stored in other directories, such as /bin/, /usr/bin/, /opt/, etc.
• B. One device file per hardware device. This is not true, as the /proc/ directory does not contain device files, but only virtual files that represent kernel data. Device files are usually stored in the /dev/ directory, which is another special file system that provides access to hardware devices.
• C. One file per existing user account. This is not true, as the /proc/ directory does not contain information about user accounts, but only about processes. User accounts are usually stored in the /etc/ directory, which contains configuration files, such as /etc/passwd/ and /etc/shadow/, that define the users and their passwords.
• E. One log file per running service. This is not true, as the /proc/ directory does not contain log files, but only information files. Log files are usually stored in the /var/log/ directory, which contains various files that record the activities of the system and the services.

References:

• The /proc Filesystem — The Linux Kernel documentation
• A Beginner’s Guide to the /proc File System in Linux - Tecmint
• Appendix E. The proc File System Red Hat Enterprise Linux 6 | Red Hat …
• Chapter 5. The proc File System Red Hat Enterprise Linux 4 | Red Hat …
• proc file system in Linux - GeeksforGeeks

The return value of a shell script after successful execution is 0. This is a convention followed by most UNIX and Linux commands, programs, and utilities. A return value of 0 indicates that the command or script completed successfully, without any errors. A return value of non-zero (1-255) indicates that the command or script failed, and the value can be interpreted as an error code. The return value of a command or script is stored in the special variable $? and can be used to test the outcome of a command or script123. For example, the following script will print a message based on the return value of the ls command:

#!/bin/bash ls if [ $? -eq 0 ]; then echo “ls command executed successfully” else echo “ls command failed” fi

References: 1: Exit and Exit Status - Linux Documentation Project 2: Linux Passwd Command Help and Examples 3: bash - Which is the best way to check return result? - Unix & Linux Stack Exchange

 The top command is a Linux command that shows the running processes on the system. It provides a dynamic real-time view of the system performance and resource usage. The top command can display various information about the processes, such as their process ID, user, priority, state, CPU and memory usage, command name, and more. The top command can also sort the processes by different criteria, such as CPU or RAM consumption, by using the interactive commands. The top command is useful for monitoring the system load and identifying the processes that are consuming the most resources. References:

• Linux Essentials Topic 104: The Linux Operating System, section 104.3: Basic features and commands of the Linux standard shells.
• Linux Essentials Topic 106: Security and File Permissions, section 106.4: Monitor and manage Linux processes.

The correct permissions for the /tmp directory are rwxrwxrwt, which means that the owner, group, and others have read, write, and execute permissions, and that the sticky bit is set. The sticky bit is a special permission that prevents users from deleting or renaming files that they do not own in a shared directory. The /tmp directory is used for storing temporary files that may be created by different users and processes, so it needs to be accessible and writable by all, but also protected from unauthorized deletion or modification of files. The rwxrwxrwt permissions can be set by using the chmod command with either the octal mode 1777 or the symbolic mode a+trwx. References: : [File system permissions] : [Sticky bit] : [chmod]

Linux passwords are not stored in plain text, but in a scrambled or encrypted form known as a hash. A hash is a one-way function that transforms a string of characters into a fixed-length value. The same input always produces the same hash, but it is impossible to reverse the process and recover the original input from the hash. This way, the system can verify the user’s password without exposing it to anyone who can read the file where the hashes are stored. The file that contains the password hashes is /etc/shadow, which is only readable by the root user or members of the shadow group. The passwd utility is used to change the user’s password, which updates the hash in the /etc/shadow file. References: Linux Essentials 1.6 Topic 105: Security and File Permissions, How to Change Account Passwords on Linux, Where is my password stored on Linux?

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

A web server is a program that listens for requests from web browsers and serves web pages, images, or other resources. Apache HTTPD and NGINX are two popular web servers that can run on Linux systems. They can handle multiple protocols, such as HTTP, HTTPS, FTP, and SMTP. Postfix, Curl, and Dovecot are not web servers, but they are related to web or network services. Postfix is a mail transfer agent (MTA) that can send and receive emails. Curl is a command-line tool that can transfer data from or to a web server. Dovecot is a mail delivery agent (MDA) that can store and retrieve emails from a local mailbox. References:

• Linux Essentials - Linux Professional Institute (LPI), section 1.2 Major Open Source Applications
• LPI Linux Essentials 010-160 - Testprep Training Tutorials, section 4.4 Your Computer on the Network

The su command stands for substitute user or switch user. It allows you to run a shell or a command as another user, usually the superuser or root. To use the su command, you need to know the password of the target user. For example, if you want to switch to the root user, you can type su - and enter the root password. This will give you a root shell, where you can execute commands with administrative privileges. To exit the root shell, you can type exit or press Ctrl-D. The su command is not the default shell of the root account, nor can it only be used by the root user. It can be used by any user who knows the password of another user. The su command does not change the name of the main administrator account, which is always root on Linux systems. The su command also does not lock the root account in specific time frames, although there are other ways to do that, such as using the pam_time module. References:

• Linux Essentials - Linux Professional Institute (LPI), section 5.1.1
• LPI Linux Essentials Study Guide: Exam 010 v1.6, 3rd Edition, chapter 9, page 219.

A recursive directory listing is a way of displaying the files and folders in a directory and all its sub-directories. The recursive option can be used with various commands, such as ls, find, or dir, to list the files recursively. For example, the command ls -R will list all the files and folders inthe current directory and any sub-directories, showing the hierarchy of the file system123 A recursive directory listing does not include the permissions, ownership, or file system details ofthe files, unless specified by other options. For example, the command ls -lR will list the files recursively and also show the permissions, ownership, size, and modification date of each file1 A recursive directory listing also does not include a preview of the content of each file, unless specified by other options. For example, the command ls -R --file-type will list the files recursively and also show the file type indicator, such as / for directories, * for executable files, @ for symbolic links, etc1 References: 1: ls (Unix) - Wikipedia 2: Recursively List all directories and files - Stack Overflow 3: Why is ls -R called “recursive” listing? - Ask Ubuntu

The correct command to create an archive file work.tar from the contents of the directory ./work/ is tar –cf work.tar ./work/. This command uses the -c option to create a new archive, the -f option to specify the file name, and the ./work/ argument to indicate the source directory. The other commands are incorrect for various reasons:

• A. tar --new work.tar ./work/ is incorrect because there is no --new option in the tar command. The correct option for creating a new archive is --create or -c.
• C. tar –create work.tgz –content ./work/ is incorrect because the -content option is not valid. The correct option for specifying the source files or directories is --files-from or -T. Also, the work.tgz file name implies compression, but the command does not use any compression option such as -z, -j, or -J.
• D. tar work.tar < ./work/ is incorrect because the tar command does not accept input redirection from the standard input. The correct way to use the tar command is to provide the options and arguments after the command name.
• E. tar work > work.tar is incorrect because the tar command does not produce output redirection to the standard output. The correct way to use the tar command is to use the -f option to specify the output file name. References: : tar command in Linux with examples - GeeksforGeeks : tar Command in Linux With Examples | phoenixNAP KB

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.

 In Linux, every file and directory is associated with an owner and a group. The owner is the user who created the file or directory, and the group is the group to which the owner belongs. Therefore, each file is owned by exactly one user and one group. This is true for option A. The other options are false for the following reasons:

• Option B: The owner of a file does not always have full permissions when accessing the file. The permissions are determined by the file mode, which can be changed by the owner or the root user. The file mode specifies the read, write, and execute permissions for the owner, the group, and others. The owner can have different permissions than the group or others.
• Option C: The user owning a file does not have to be a member of the file’s group. The owner can change the group ownership of the file to any group on the system, regardless of whether the owner belongs to that group or not. However, only the root user or a user with the CAP_CHOWN capability can change the group ownership to a group that the owner is not a member of.
• Option D: When a user is deleted, all files owned by the user do not disappear. The files remain on the system, but their owner is changed to an invalid user ID (UID). The files can still be accessed by the group or others, depending on the permissions. The files can also be reclaimed by the root user or a user with the CAP_CHOWN capability, who can change the owner to a valid user.
• Option E: The owner of a file can be changed once it is assigned to an owner. The owner can transfer the ownership to another user, or the root user or a user with the CAP_CHOWN capability can change the owner to any user on the system. The command to change the owner of a file is chown. References: 1: Chown Command in Linux (File Ownership) | Linuxize 2 3: Linux File Permissions and Ownership Explained with Examples 4 2: 3 Ways to Find File Owner in Linux - howtouselinux 1