Chapter 1,2 - Installing Red Hat Enterprise Linux, Using Essential Tools

Question 1

What is Linux?

Answer 1

Linux is a free operating system. That means that the source code of all programs is available for free. However, some enterprise Linux distributions are sold as commercial products, with bundled support and maintenance, which is the case for RHEL 8

Question 2

What are the two free alternatives to Redhat?

Answer 2

CentOS 8

Fedora

Question 3

What is a Repository?

Answer 3

A repository is the installation source used for installing software. If you are using free software such as CentOS, correct repositories are automatically setup, and no further action is required. If you are using Red Hat Enterprise Linux with a subscription, you’ll need to use the Subscription Manager software to get
access to repositories.

Question 4

What is the default file system RHEL 8 uses?

Answer 4

RHEL 8 by default uses the XFS file system. This file system cannot be shrunk; it can only be expanded. Therefore, it is sometimes a better choice to use Ext4.

Question 5

What is a Shell?

Answer 5

The shell is the default working environment for a Linux administrator. It is the environment where users and administrators enter commands that are executed by
the operating system.

Question 6

Which is the most common shell used?

Answer 6

Different shells for Linux are available, but Bash is the most common shell.

Question 7

What are the 3 basic parts of a command?

Answer 7

the command, its options, and its arguments.

Question 8

What are the 3 different kind of commands?

Answer 8

Aliases - An alias is a command that a user can define as needed
Internal Commands - An internal command is a command that is a part of the shell itself and, as such,
doesn’t have to be loaded from disk separately
External Commands - An external command is a command that exists as an executable file on the disk of the computer

Question 9

Where are the external commands looked at when executed?

Answer 9

the $PATH variable.

Question 10

To find out which exact command the shell is using and from where is it being loaded?

Answer 10

which command

Question 11

What are the I/O redirection file descriptor numbers?

Answer 11

NAME - FILE DESCRIPTOR
STDIN - 0
STDOUT - 1
STDERR - 2

Question 12

How do you redirect STDERR to the same destination as STDOUT?

Answer 12

2>&1

eg. ls whuhiu > errout 2>&1

Question 13

What is a device file in Linux?

Answer 13

A device file on Linux is a file that is used to access specific hardware. eg.
HDD - /dev/sda, the console of your server is known as /dev/console or /dev/tty1

Question 14

Which command to show a list of all commands in the Bash history?

Answer 14

history

Question 15

How to execute a command with a specific number from history?

Answer 15

!number

Question 16

How to execute the last command that starts with “sometext”?

Answer 16

!sometext

Question 17

which command to clear the current history?

Answer 17

history -c

Question 18

How to remove the complete Bash history?

Answer 18

type “history -w” immediately after using “history -c”

Question 19

What are the vi or vim editor options?

Answer 19

vim Command = Explanation
/text = Searches for text from the current cursor position forward.
?text = Searches for text from the current cursor position backward.
^ = Goes to the first position in the current line.
$ = Goes to the last position in the current line.
!ls = Adds the output of ls (or any other command) in the current file.
:%s/old/new/g =Replaces all occurrences of old with new.

Question 20

Which is the option to delete a line in vi or vim editor?

Answer 20

:dd

Question 21

What does the environment configuration file “/etc/profile” contain?

Answer 21

This is the generic file that is processed by all users upon login

Question 22

What does the environment configuration file “/etc/bashrc” contain?

Answer 22

This file is processed when subshells are started

Question 23

What does the environment configuration file “~/.bash_profile” contain?

Answer 23

In this file, user-specific login shell variables can be defined

Question 24

What does the environment configuration file “~/.bashrc” contain?

Answer 24

In this user-specific file, subshell variables can be defined

Question 25

What is a login shell and what is a sub shell?

Answer 25

A login shell is the first shell that is opened for a user after the user has logged in. From the login shell, a user may run scripts, which will start a subshell of that
login shell.

Question 26

what is the use of “/etc/motd” and “/etc/issue”?

Answer 26

Messages in /etc/motd display after a user has successfully logged in to a shell. Another way to send information to users is by using /etc/issue. The contents of this file display before the user logs in.

Question 27

Which command to use to find information in man pages or search the man pages?

Answer 27

you can search the mandb database by using

“apropos” or “man -k”

Question 28

What are the different categorizations of man pages?

Answer 28

1: Executable programs or shell commands
5: File formats and conventions
8: System administration commands

Question 29

Which command to use to update the mandb database?

Answer 29

mandb