Introduction to Linux & the Command Line

Question 1

What is the history of Linux? Who created it?

Answer 1

Created by Linus Torvalds
1991
Student in Finland

Question 2

So who combines GNU with Linux?

Answer 2

Red Hat
Canonical
Debian
Slackware
Linux Family Tree (https://distrowatch.com/dwres.php?resource=family-tree)

Question 3

Which distributions should we be familiar with for the exam?

Answer 3

CentOS

Ubuntu

Question 4

How do we access the command line interface?

Answer 4

Boot direct to console
Terminal software:
 XTERM
Konsole
Gnome Terminal

Question 5

Is the CLI the same on all Linux distros?

Answer 5

/bin/sh
     -Generally links to another shell
Red Hat / CentOS
     -/bin/bash
Ubuntu
    -/bin/dash

Question 6

How do we execute commands in the CLI?

Answer 6

Typing them into the terminal.
*Single commands
ls
history
*Options/Arguments
uname
uname -a
shutdown -h now

Question 7

What are some common commands we may use?

Answer 7

ls
mkdir
cd
pwd
echo
touch
cp

Question 8

Can we edit files from within the CLI?

Answer 8

YES

• View
  
  • cat
  • more
  • less
• Edit
  
  • vim
  • nano
  • gedit

Question 9

Are there any other tips or tricks for the CLI?

Answer 9

Tab auto-complete

Question 10

When do we need super user privileges?

Answer 10

System-wide changes
Changes that affect other users
Configuring some services

Question 11

What is the easiest way to access super user privileges?

Answer 11

*su
   Substitute user
*su -
  Switch to root
   - loads normal environment
*su - (username)
   Switch to user

Function: Change user ID or become superuser

Question 12

What if I just want to perform a single command?

Answer 12

*sudo
Executes command as root
Password cached for five minutes by default

Question 13

Who is allowed to use the sudo command?

Answer 13

Administrators
*Users must be authorized to run sudo
In some distros (like Ubuntu) simply add ‘sudo’ group as a
secondary group
In others (like Red Hat) you must create your own group and
add it to /etc/sudoers

visudo =
dpezet ALL=(ALL)

Question 14

What command allows users to securely edit files?

Answer 14

• sudoedit
  
  • Useful when editing a single write-protected file
  • sudoedit /etc/hosts

Question 15

What does bash stand for?

Answer 15

Bourne Again Shell

Question 16

What is the ls command?

Answer 16

ls = list

Function: List information about the files (the current directory by default)

Question 17

What is the history command?

Answer 17

Displays a list of commands previously used in the terminal session.
history allows users to reuse any listed command without retyping it.

Question 18

What is the uname command?

Answer 18

The uname command is used to print basic system information. It is usually invoked with the -a option to display all available information.

Question 19

What is the mkdir command?

Answer 19

The mkdir command in Linux/Unix allows users to create or make new directories.

Question 20

What is the cd command?

Answer 20

The cd (“change directory”) command is used to change the current working directory in Linux and other Unix-like operating systems.

Question 21

What is the pwd command?

Answer 21

pwd stands for Print Working Directory. It prints the path of the working directory, starting from the root.

Question 22

What is the echo command?

Answer 22

echo command in linux is used to display a line of text/string that is passed as an argument .

Question 23

What is the touch command?

Answer 23

The touch command’s primary function is to modify a timestamp. Commonly, the utility is used for file creation, although this is not its primary function.

Question 24

What is the cp command?

Answer 24

The Linux cp command is used for copying files and directories to another location.

Question 25

What is the cat command?

Answer 25

The cat (short for “concatenate“) command is one of the most frequently used commands in Linux/Unix-like operating systems. cat command allows us to create single or multiple files, view content of a file, concatenate files and redirect output in terminal or files.

Question 26

What is the more command?

Answer 26

more command is used to view the text files in the command prompt, displaying one screen at a time in case the file is large (For example log files).

Question 27

What is the less command?

Answer 27

The less command is a Linux terminal pager that shows a file’s contents one screen at a time. It is useful when dealing with a large text file because it doesn’t load the entire file but accesses it page by page, resulting in fast loading speeds.

Question 28

What is the vim command?

Answer 28

Vim is a text editor that is an upgraded version of the Vi editor and is more compatible with Vi. The most usage of vi editors is to create a new file, edit an existing file, or just read a file.

Question 29

What is the nano command?

Answer 29

GNU nano is a simple terminal-based text editor. Though not as powerful as Emacs or Vim, it is easy to learn and use. Nano is ideal for making small changes to existing configuration files or for writing short plain text files.

Question 30

What is the gedit command?

Answer 30

gedit is the official text editor of the GNOME desktop environment.
While aiming at simplicity and ease of use, gedit is a powerful general purpose text editor. It can be used to create and edit all kinds of text files.

Question 31

What is the su command?

Answer 31

The su command is used to switch to another user, in other words change user ID during a normal login session (that is why it is sometimes referred to as switch (-) user by a number of Linux users).

Question 32

What is the sudo command?

Answer 32

sudo , which is an acronym for superuser do or substitute user do, is a command that runs an elevated prompt (permissions) without a need to change your identity.

Question 33

What is the visudo command?

Answer 33

The visudo command opens a text editor like normal, but it validates the syntax of the file upon saving. This prevents configuration errors from blocking sudo operations, which may be your only way of obtaining root privileges.

Question 34

What is the sudoedit command?

Answer 34

Sudoedit is a built-in command that allows users to securely edit files. According to the sudo man page, ‘sudoedit’ is equivalent to executing ‘sudo’ with the ‘-e’ command line option.