operating systems exam

Question 1

Get root privilege for one command only

Answer 1

sudo <mycommand></mycommand>

Question 2

Update the repository.

Answer 2

sudo apt update

Question 3

Get an app from the repository

Answer 3

sudo apt install <name></name>

Question 4

Remove an app from the repository

Answer 4

sudo apt remove <name></name>

Question 5

Clear the screen

Answer 5

clear

Question 6

prints the full name (the full path) of current/working directory

Answer 6

pwd

Question 7

list the names and features of files and directories

Answer 7

ls

Question 8

list information about files and directories within the file system

Answer 8

ls -l

Question 9

change current working directory

Answer 9

cd

Question 10

prints the previously used directory and changes to it.

Answer 10

cd -

Question 11

to display the contents of a file

Answer 11

cat <filename></filename>

Question 12

o see the virtual memory swap file called swapfile in the root directory

Answer 12

ls –l /

Question 13

To see disk information

Answer 13

sudo fdisk -l

Question 14

what is an iso file

Answer 14

An ISO file is an exact copy of an entire optical disk such as a CD, DVD, or Blu-ray archived into a single file.

Question 15

display the contents of a directory in ascending order alphabetically

Answer 15

dir

Question 16

go back to the parent directory

Answer 16

cd..

Question 17

go back to the root directory

Answer 17

cd /

Question 18

sudo apt install <filename></filename>

Answer 18

installs an application

Question 19

display the free disc space of a specific file system.

Answer 19

df -l

Question 20

show information (manual) about a command

Answer 20

man

Question 21

switch to a different user

Answer 21

su

Question 22

edit files/creates files

Answer 22

nano

Question 23

copies file

Answer 23

cp

Question 24

removes file

Answer 24

rm

Question 25

moves file

Answer 25

mv

Question 26

check if server is up and running
eg ping www.rte.ie

Answer 26

ping

Question 27

create a file directory (folder)

Answer 27

mkdir <name></name>

Question 27

edits a file

Answer 27

gedit

Question 28

describe each directory
i. home
ii. /bin
iii. /etc
iv. /usr

Answer 28

home = is a directory for a particular user of the system and consists of individual file
bin = includes basic binaries that are required for the system’s basic function.
etc = contains system configuration information
usr = the location of user programs and files

Question 29

search and matches text patterns in files contained in the regular expressions.

Answer 29

grep

Question 30

run a program typed in a text file

Answer 30

bash

Question 31

display a line of text

Answer 31

echo

Question 32

display the last line of a file

Answer 32

tail

Question 33

display the first line of a file

Answer 33

head

Question 34

change file permissions

Answer 34

chmod

Question 35

chmod info (sorry its long i was too lazy to make more docs notes)

Answer 35

The chmod command in Linux is used to change the permissions of files and directories. “chmod” stands for “change mode”. Permissions in Linux determine who can read, write, or execute a file or directory. The chmod command allows you to modify these permissions for the owner of the file, members of the group associated with the file, and other users.

Here’s the basic syntax of the chmod command:

chmod [permissions] [file]

The [permissions] part specifies which permissions you want to set, and [file] is the name of the file or directory for which you want to change permissions.

Permissions are represented by three types:

User (Owner):

r (read): Allows the owner to read the file or directory.
w (write): Allows the owner to write to the file or directory.
x (execute): Allows the owner to execute the file (if it’s a program) or access the directory.
Group:

r: Allows members of the group to read the file or directory.
w: Allows members of the group to write to the file or directory.
x: Allows members of the group to execute the file (if it’s a program) or access the directory.
Others:

r: Allows other users (those who are not the owner or members of the group) to read the file or directory.
w: Allows other users to write to the file or directory.
x: Allows other users to execute the file (if it’s a program) or access the directory.
Each type of permission is represented by a number:

r (read) is represented by 4.
w (write) is represented by 2.
x (execute) is represented by 1.
To set permissions using chmod, you add up the numbers for each type of permission you want to grant. For example:

chmod 755 file.txt would give the owner of file.txt read, write, and execute permissions (7), and read and execute permissions to the group and others (5).
Remember, modifying permissions with chmod can have significant security implications, so it’s important to use it carefully and only grant the necessary permissions to users and groups.

Question 36

what does u , g and o stand for in chmod permissions

Answer 36

user -(owner)
group
other (everyone else)
eg. ugo+rwx would grant read, write, and execute permissions to the owner, the group, and others on a file or directory.

Question 37

what is linux

Answer 37

Linux is a free, open-source operating system that manages the communication between your software and hardware.

Question 38

What is Ubuntu?

Answer 38

Xubuntu is a version of Ubuntu that uses a different interface called XFCE, which is simpler and uses less computer resources .

Question 39

list the disk usage

Answer 39

du

Question 40

list the processes

Answer 40

ps

Question 41

Write entire content of the grep manual page into a file named hold, allowing you to review the manual’s contents at a later time using a text editor or another command like cat hold.

Answer 41

man grep > hold

Question 42

the name of a file where the output of the man grep command is being redirected and stored.

Answer 42

hold

Question 43

you have a left side program and a right side program. The pipe operator ‘|’ is between the two programs. The output data fro m the left side program will not be displayed on the terminal screen, instead it is redirected to the pipe.
Then, the right side program reads the data from the pipe as its input

Answer 43

cat hold | more

Question 44

Run every written line in the program with nano command.

Answer 44

bash (MyProgram)

Question 45

tail -8 passwd Displays the last 8 lines of the file passwd, typically located in the /etc directory. This file contains user account information.

Answer 45

tail -8 passwd

Question 46

what is a softlink

Answer 46

files that point to a file or directory in your system, but don’t mirror the other file’s data

Question 47

what is a hardlink

Answer 47

a direct reference to a file’s data on the disk. It has the same name, inode number, and permissions as the original file. You can create a hard link with the. ln. command, without any options.