Question 1

What can be found in the /proc/ directory?

Accepted Answer

D

Explanation: 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’, which points 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. Reference: 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

Question 2

Which permissions are set on a regular file once the permissions have been modified with the command chmod 654 file.txt?

Accepted Answer

E

Explanation: The chmod command is used to change the permissions of files and directories. The permissions are represented by three sets of three characters, indicating the permissions for the owner, the group, and the others. Each character can be either r (read), w (write), x (execute), or - (no permission). The chmod command can use either symbolic or numeric mode to specify the permissions. In this question, the numeric mode is used, which consists of three digits from 0 to 7. Each digit is the sum of the permissions for each set, where r is 4, w is 2, and x is 1. For example, 7 means rwx, 6 means rw-, and 4 means r–. Therefore, the command chmod 654 file.txt sets the permissions as follows: The first digit 6 means rw- for the owner, which means the owner can read and write the file, but not execute it. The second digit 5 means r-x for the group, which means the group can read and execute the file, but not write it. The third digit 4 means r-- for the others, which means the others can only read the file, but not write or execute it. The resulting permissions are -rw-r-xr–, which is the correct answer. The other options are incorrect because they either have the wrong permissions or the wrong file type. A regular file does not have the d (directory) prefix, and a directory cannot have the - (no file type) prefix. Reference: Linux Essentials Version 1.6 Objectives: 4.1. Ownership and Permissions1 Linux Essentials Version 1.6 Exam Study Resources: Linux Essentials Manual - Chapter 8. Security and File Permissions - 8.1. Ownership and Permissions - 8.1.1. The chmod Command2 Linux Essentials Version 1.6 Exam Study Resources: Linux Essentials Manual - Appendix A. Answers to the Exercises - Chapter 8. Security and File Permissions - 8.1. Ownership and Permissions - Exercise 8.1.12

Question 3

Which of the following commands puts the lines of the file data.csv into alphabetical order?

Accepted Answer

B

Explanation: The sort command is used to sort the lines of a file or a stream of input according to a specified criterion, such as alphabetical order, numerical order, reverse order, etc. By default, the sort command sorts the lines in ascending alphabetical order, using the first character of each line as the key. For example, the command sort data.csv will sort the lines of the file data.csv in alphabetical order and display the output on the screen. If you want to save the sorted output to a new file, you can use the redirection operator (>) to specify the output file name. For example, the command sort data.csv > sorted_data.csv will sort the lines of the file data.csv in alphabetical order and save the output to a new file named sorted_data.csv. The other commands are either invalid or do not perform the sorting operation. The a…z command does not exist, the abc command is a text editor, the wc command counts the number of words, lines, and bytes in a file, and the grep command searches for a pattern in a file or a stream of input. Therefore, the correct answer is B. Reference: Linux Essentials - Linux Professional Institute (LPI), section 2.3.2 LPI Linux Essentials Study Guide: Exam 010 v1.6, 3rd Edition, chapter 4, page 95.

Question 4

Which of the following programs are web servers? (Choose two.)

Accepted Answer

Explanation: 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. Reference: 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

Question 5

The file script.sh in the current directory contains the following content:
#!/bin/bash echo $MYVAR
The following commands are used to execute this script:
MYVAR=value
./script.sh
The result is an empty line instead of the content of the variable MYVAR. How should MYVAR be set
in order to make script.sh display the content of MYVAR?

Accepted Answer

E

Explanation: The reason why the script.sh does not display the content of the variable MYVAR is that the variable is not exported to the environment of the script. When a script is executed, it runs in a separate process that inherits the environment variables from the parent process, but not the shell variables. A shell variable is a variable that is defined and visible only in the current shell session, while an environment variable is a variable that is exported to the environment and visible to all processes that run in that environment1. To make a shell variable an environment variable, we need to use the export command. The export command takes a shell variable name and adds it to the environment of the current shell and any subshells or processes that are created from it2. For example, to export the variable MYVAR with the value value, we can use: export MYVAR=value This will make the variable MYVAR available to the script.sh when it is executed, and the script will print the value of MYVAR as expected. Alternatively, we can also use the export command with the - n option to remove a variable from the environment, or with the -p option to list all the environment variables2. The other options are not valid ways to set MYVAR as an environment variable. The !MYVAR=value option is not a valid syntax for setting a variable in bash. The env MYVAR=value option will run the env command with the MYVAR=value argument, which will print the environment variables with the addition of MYVAR=value, but it will not affect the current shell or the script.sh3. The MYVAR=value option will set MYVAR as a shell variable, but not as an environment variable, so it will not be visible to the script.sh1. The $MYVAR=value option will try to set the variable whose name is the value of MYVAR to the value value, which is not what we want4. Reference: Linux Essentials Exam Objectives, Version 1.6, Topic 103.1, Weight 2 Linux Essentials Certification Guide, Chapter 3, Page 51-52 env(1) - Linux manual page Bash Variables - LinuxConfig.org

Question 6

Reverse DNS assigns hostnames to IP addresses. How is the name of the IP address 198.51.100.165 stored on a DNS server?

Accepted Answer

B

Explanation: 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. Reference: 1: Reverse DNS lookup - Wikipedia 1

Question 7

The current directory contains the following file:
-rw-r—r— 1 root exec 24551 Apr 2 12:36 test.sh
The file contains a valid shell script, but executing this file using ./test.sh leads to this error:
bash: ./test.sh: Permission denied
What should be done in order to successfully execute the script?

Accepted Answer

B

Explanation: The execute bit in Linux is a permission bit that allows the user to run an executable file or enter a directory. For regular files, such as scripts or binaries, the execute bit must be set for the user to run them. For directories, the execute bit allows the user to access the files and subdirectories inside. Therefore, to successfully execute the script test.sh, the execute bit should be set in the file’s permissions. This can be done by using the chmod command with the +x option, for example: chmod +x test.sh. The other options are either irrelevant or incorrect. The file’s extension does not affect its executability, only its association with a program. The user executing the script does not need to be in the exec group, as long as the user has the execute permission on the file. The SetUID bit is a special permission bit that allows the user to run the file as the file’s owner, regardless of the user’s identity. This is not necessary for executing the script, and may pose a security risk. The #!./test.sh syntax is invalid, as the #! is used to specify the interpreter for the script, not the script itself. Reference: Linux Essentials Version 1.6 Objectives1, Topic 1.4: Command Line Basics, Subtopic: Basic Shell Commands Linux Essentials Version 1.6 Exam Preparation Guide2, Section 1.4: Command Line Basics, Page 16 Execute vs Read bit. How do directory permissions in Linux work?3

Question 8

Which command displays file names only and no additional information?

Accepted Answer

A

Explanation: The ls command is used to list the files and directories in a given path. By default, the ls command displays only the file names, without any additional information. However, the ls command can also take various options to modify its output. For example, the -l option tells ls to display the long format, which includes the file permissions, owner, group, size, date, and name. The -h option tells ls to display the file sizes in a human-readable format, such as KB, MB, GB, etc. The -a option tells ls to display all files, including the hidden ones that start with a dot (.). The -n option tells ls to display the numeric user ID and group ID instead of the user name and group name. Therefore, the only option that does not add any additional information to the file names is the -a option. The command ls -a will display all the file names in the current directory, including the hidden ones, but nothing else. Reference: Linux Essentials - Linux Professional Institute (LPI), section 2.1.1 2.1 Lesson 1 - Linux Professional Institute Certification Programs, slide 6.

Question 9

What command displays manual pages? (Specify ONLY the command without any path or parameters.)

Accepted Answer

Explanation: The command that displays manual pages for Linux commands is the man command. The man command is used to display the manual pages for a given command or topic. For example, to view the manual page for the ls command, you can type: man ls This will open the manual page for the ls command in a pager, which allows you to scroll and search through the text. You can also specify the section number of the manual page if there are multiple pages with the same name. For example, to view the manual page for the passwd command in section 1, you can type: man 1 passwd The man command is one of the most useful and important commands for learning and using Linux. It provides detailed information about the syntax, options, arguments, examples, and other aspects of a command or topic. You can also use the --help option to get a brief summary of the usage and options of a command. For example, to get a quick help for the man command, you can type: man --help To learn more about the man command and how to use it effectively, you can refer to the following resources: Linux Essentials Exam Objectives, Version 1.6, Topic 103.1, Weight 2 Linux Essentials Certification Guide, Chapter 3, Page 51-52 How to Access Manual Pages for Linux Commands - Linux Tutorials - Learn Linux Configuration How to Easily Read a Linux Man Page - Make Tech Easier

Question 10

What parameter of ls prints a recursive listing of a directory's content? (Specify ONLY the option name without any values or parameters.)

Accepted Answer

Explanation: 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. Reference: Use ls Command Recursively - Linux Handbook How to List Files Recursively in Linux command line

Question 11

When typing a long command line at the shell, what single character can be used to split a command across multiple lines?

Accepted Answer

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

Question 12

FILL BLANK What keyword is used in a shell script to begin a loop? (Specify one keyword only, without any additional information.)

Accepted Answer

Explanation: The keyword for is used in a shell script to begin a loop that iterates over a list of items or a range of numbers. The syntax of the for loop is as follows: for in do done The variable is assigned to each element of the in turn, and the are executed for each iteration. The can be a sequence of words, numbers, filenames, or other values. If the is omitted, the for loop will iterate over the positional parameters ($1, $2, …). The do and done keywords mark the beginning and the end of the loop body, respectively. The for loop is one of the three types of loops in shell scripting, along with the while and until loops. Reference: 1: Looping Statements | Shell Script - GeeksforGeeks 1 2: unix - Shell script "for" loop syntax - Stack Overflow 2 3: For Loop Shell Scripting - javatpoint 3

Question 13

Which of the following outputs comes from the command free? https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/LPI_010-160/page_6_img_1.jpg

Accepted Answer

E

Explanation: :

Question 14

Which of the following commands output the content of the file Texts 2.txt? (Choose two.)

Accepted Answer

Explanation: 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’ Reference: 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

Question 15

What is true about the su command?

Accepted Answer

C

Explanation: 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. Reference: 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.

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