If you take a look at /etc/passwd file‘s content, you‘ll find out that
the first column is a user name,
the third column is UID
and the last column is its default shell.
Long-long ago this file used to store password HASH. But nowadays not everyone even remember that as it‘s not so anymore.

The Raspberry Pi does not come with an OS because it doesn‘t contain an onboard hard drive of flash memory for storage. The OS and user files are all stored on a micro SD card that is inserted into the board itself.

The export command is a built-in Bash shell command that exports environmental variables as child processes.
The question scenario reproduced in screenshot. The solution emphasized:

Screenshot with the last command output as an illustration:

q‘ stands for quit. So, this is the key to exit the less viewer (as well as many others programs in Linux terminal)

Red Hat Enterprise Linux (RHEL) is an upstream source for CentOS (from Community Enterprise Operating System).

Every command returns an exit status. A successful command returns a 0, while an unsuccessful one returns a non-zero value that usually can be interpreted as an error code.

On Linux the superuser account is root, which always has UID=0

During installation, Linux takes the first hard disk found and assigns it the value sda.
If we have multiple partitions in the hard disk, the system consecutively appended a number starting from sda1  to sda15. In a single hard disk, we can only have a maximum of 15 partitions.
So, /dev/sda2 should represents a second hard disk partition

To check the answer out just run (for one-line help about top)
whatis top
and then (to launch top with sorting by %CPU column)
top -o %CPU
in Linux terminal.
And you‘ll find everything out yourself.

The only correct statement is
Each file is owned by exactly one user and one group.
which can be proved by the output of ls -l command

Both disk types can fail due to physical damage.
Ordinarily Hard disk drives can store many times as much data as Solid state disks.
So.
Hard disks have a motor and moving parts, solid state disks do not. (True)
Solid state disks provide faster access to stored data than hard disks. (True)

LTS stands for Long Term Support. And the question implies several years of maintenance (which is relatively Long Term). So, Ubuntu LTS suits the goal.
And Red Hat is a particularly reliable distro of Linux suitable for deployment as a server.

To make sure that passwords are kept in HASHed form, we can take a look at /etc/shadow file:

Private web browsing does not forbid printing of web pages.
You can login to website while working in private browser.
Other assertions are true.

Hint: rpm stands for Red-Hat Package Management

We execute a bash script by writing its path, like
./test.sh
or by passing its name as an argument when launching bash directly, like
bash test.sh

First, to search for the files in Linux terminal we use find command. Then, we define the directory where we‘re going to do our search. And then, after the ‘-name‘ option we can specify the filename or pattern.
For more into type man find in the console.

The command for a user creation is useradd. The ‘-m‘ option in it is used to declare the necessity of home directory creation. Don‘t forget about the root privileges when using this command.
You can find additional help by typing useradd –help in the command line.

The /usr/share/doc is the folder, where you can find the documentation files for programs installed on your system.
The /etc folder comprises all system-wide configuration files and some shell scripts that are executed during the system boot.
The /var contains files that are of variable content, so their content is not static and it constantly changes, like log files.

The trick in this question is the space within the file name (before the 2 digit), which forces us to use whether the quotes or the left slash to mention our file.
Correct commands are emphasized on the screenshot:

Commonly used record types:
A (Host address)
AAAA (IPv6 host address)
ALIAS (Auto resolved alias)
CNAME (Canonical name for an alias)
MX (Mail eXchange)
NS (Name Server)
PTR (Pointer)
SOA (Start Of Authority)
SRV (location of service)
TXT (Descriptive text)
So, for this question the correct answers should be A and AAAA.

-R option of ls command lists subdirectories recursively. Please, pay attention, that the ‘R‘ letter is uppercase (letters case is extremally important in Linux).
You can find more help on this question by typing ‘ls –help’ in Linux console.

Apache and Nginx are the most famous Linux web servers.

1. A symbolic link can point to a file or to a directory.
2. A hard link can only point to a file and never to a directory (opposite to offered answer).
3. When the target of the symbolic link is moved, the link breaks.
4. A symbolic link can point to a file on another file system (TRUE STATEMENT).
5. A user is not forbidden to create hard links by default.
You can find more info on links topic by typing ln –help or man ln in the terminal

The command that changes the ownership of the files is chown (acronym for ‘change owner‘).
Its correct syntax is this:
chown [user] [target_file]
Don‘t forget sudo prefix.

When we read some variable (like PATH), we have to use the dollar sign in front of it.
When we change a variable, we don‘t use the dollar sign.
So.
export PATH=/new/dir:$PATH is correct
This option PATH=/new/dir:PATH is almost the working one if only it had the dollar sign on the left PATH=/new/dir:$PATH

Paid of Free software is about conditions of its use.
It has nothing to do with tech docs, nor programming languages, nor list of libraries.

All code samples but one have syntax error in bash shell.

/var contains variable data files. This includes spool directories and files, administrative and logging data, and transient and temporary files. Some portions of /var are not shareable between different systems.

The correct syntax for the zip command is this:
zip [output_file_name] [input_files_list]

tar command is used for archiving files.
-x option — for extracting files from an archive
-z option — to filter the archive through gzip
-f option — to work with files
-c option — to create a new archive
More help you can find by typing tar –help in the command line.

The key in this question is the first column in the directory content, which is -rw-r–r–
There we can see that the file doesn‘t have an executing privilege. And this is the reason for the resulting error.
So, to solve this we have to add the execution permission for the file (to the owner of the file, at least).
The solution could look like: chmod u+x test.sh
The case is reproduced in screenshot:

The two dots statement is the designation of the parent directory.
So, by running that command a user should go first one level up and then to Documents directory there.
Proof from the console (the cd command added for illustration):

Because CentOS Linux was derived from Red Hat Enterprise Linux sources, users migrating to Red Hat can continue to use many of the same techniques and elements with minimal training, while also gaining more features, tools, support, and value.

So, the tar is an archiving utility. And its‘ -c, -f options allow us to create a new archive.

Mainly there‘re two signs indicating the current type of privileges. It‘s the $ symbol, used for ordinary user, and the # sumbol, used for the root.

DHCP stands for Dynamic Host Configuration Protocol. It is the correct answer.
It is a client/server protocol that automatically provides an Internet Protocol (IP) host with its IP address and other related configuration information such as the subnet mask and default gateway.
NFS is Network File System protocol.
STMP is Simple Mail Transfer Protocol
DNS is Domain Name System
LDAP is Lightweight Directory Access Protocol

Yes. You can define a loop in a shell script by using for keyword.
For more help type man bash in Linux terminal

host is DNS lookup utility. You can prove it by launching man host command (which is a user manual for host command).
Other answers are made up commands or commands, used for other purposes.

pwd stands for print working directory
So, all that this command does is it outputs the current location.

The /etc/passwd file stores vital information about users such as username, home directory, etc.
The /etc/group file is a text file that defines the groups on the system.

The man command is an interface to the system reference manuals
For more info type man man in Linux console or type whatis man.

The process identifier (a.k.a. process ID or PID) is a positive natural number used by most operating systems to uniquely identify an active process. So, among the offered answers there is only one positive natural number.

Nothing happens to the file itself (like deletion or moving, or changing the owner).
The scenario implemented on screenshot:

Reverse DNS is a DNS lookup of a domain name from an IP address. While a regular DNS request resolves an IP address from a domain name, rDNS does the opposite, hence the name reverse.
A PTR record is used to perform reverse DNS lookups. Pointer records are configured within Address and Routing Parameter Area (in-addr.arpa) domains. If there is no PTR record set up, a reverse DNS lookup is unsuccessful.
So for correct answer just reverse the numbers in IP address.

You have the capability to change the file permissions by using numbers (3 numbers from 0 to 7). Where
first number sets permissions for the file owner,
second number sets permissions for the file group,
third number sets permissions for everyone else.
6 => rw- [read, write, not execute]
5 => r-x [read, not write, execute]
4 => r– [read, not write, not execute]
Long story short:

The easiest (and the most obvious) way to check the answer is to launch free command in Linux terminal.

sort is the command, used for arranging lines in an alphabetical order

I‘d personally love it to be a autobus. But, no. It‘s The SATA bus
The red cable in the picture is an implementation of it:

Linux hardware drivers are about its kernel, not computer BIOS, not user‘s programs

This directory contains mostly files that are required temporarily. Many programs use this to create lock files and for temporary storage of data. Which means that it‘s the best for it to have the maximum privileges by default. It is actually the default shared directory (with set up sticky bit, btw).

The asterisk symbol is the alias for any string (any file name in our case).
The question mark (?) is the alias for only one sign/letter.

In cloud computing, the cloud service provider owns, manages and maintains the assets; the customer consumes them via an Internet connection, and pays for them on a subscription or pay-as-you-go basis.
So in Linux this idea is implemented by provider-specific configuration file.

The tar command is an archiving utility.
-g option handles new GNU-format incremental backup
-b option BLOCKS x 512 bytes per record
So -z and -j options handle archiving in tar utility.
You can find more help on this question by typing ‘tar –help’ in Linux console.

The ‘-l‘ optoin in the ls command is used for a long listing format (so-called table view), which has a lot of extra info about files and folders. So, correct answer should not use -l option.
While ‘-a‘ option stands for ‘all‘ (include in the output the entries starting with the dot).

This question is about some general programming concepts. It starts from the for loop, which goes through all the files with the ‘txt’ extension. And within the loop’s body, what it does is only outputs the file name. So, in the correct answer, we will have only the names of the files that have this extension.

The man command is used to call the full user manual for other commands.
The info command is kind of the same, but also has basic hyperlinking features and a simpler markup language to use.
So, these are the commands used to get information on the proper use of any other command.

There‘s no restrictions for executable file location in Linux.
It‘s a good and common practice to start the script file with the two character sequence #! (which is called ‘shebang‘). Though it can be run without shebang.
A script cannot run without an executable permission bit set.
A script is not compiled code, it‘s a mere text file.

Obviously, ‘proc‘ stands for process.
On this screenshot these blue numbers are the folders for the running processes: