linux practical - shell commands

Question 1

how to check the version of the bash shell

Answer 1

echo $SHELL

Question 2

how to change the password in linux

Answer 2

passwd

Question 3

how do you clear the terminal

Answer 3

clear

Question 4

who do you display who is the current login user in the terminal

Answer 4

whoami

the login user name is also displayed on the terminal prompt

Question 5

how to display the current system date

Answer 5

date

eg output:
Tue Sep 15 12:00:29 SGT 2022

Question 6

Display the Day of the Week

Answer 6

Format: %A
Example: date +%A
Output: Tuesday

Question 7

Display the Day of the Month

Answer 7

Format: %d
Example: date +%d
Output: 14

Question 8

Display the Month

Answer 8

Format: %B
Example: date +%B
Output: January

Question 9

Display the Year

Answer 9

Format: %Y
Example: date +%Y
Output: 2022

Question 10

Flashcard: Change Date Separator
Format: 2023 - 01 - 14

Answer 10

example: %Y-%m-%d
Output: 2022-01-14
Description: In this example, the date separator is changed from default ‘/’ to ‘-‘

Question 11

Display the Timezone

Answer 11

Format: %Z
Example: date +%Z
Output: EST

Question 12

Display the Day of the Week (abbreviated)

Answer 12

Format: %a
Example: date +%a
Output: Tue

Question 13

Flashcard: Display the Month (numerical)

Answer 13

Format: %m
Example: date +%m
Output: 01

Question 14

Display the current year in a different format (YY)

Answer 14

Command: date +%y
Description: Display the current year in the format of YY (Year)

Question 15

Why the date command failed run when the format string does not have the single or
double quotes

Answer 15

When a format string contains spaces, it should be quoted by single or double quotes.

Question 16

how to display the current calendar of the month

Answer 16

cal

Question 17

display the calendar for 2023

Answer 17

cal 2023

Question 18

how to display a calendar with monday as the first date

Answer 18

cal -m

Question 19

how to display the calendar for may 2023

Answer 19

cal 5 2023

Question 20

how to display current, previous and next date

Answer 20

cal -3

Question 21

how to display the specific date on cal

Answer 21

cal 12 8 2022

will display 12 august 2022 on the calendar

Question 22

how to display the current month and the next 2 months

Answer 22

cal -3 2 2023

Question 23

Perform mathematical calculations

Answer 23

Command: bc -l
Example: 2+2
Output: 4
Description: bc -l can be used to perform mathematical calculations, like addition, subtraction, multiplication, division, and more. You can also use mathematical functions such as log, sin, cos, sqrt and more.

Question 24

how to Define variables to do maths calculation

Answer 24

Command: bc -l
Example: a=3; b=4; a*b
Output: 12

Example: sqrt(2)
Output: 1.41

Question 25

how can commands be embedded within a string

Answer 25

Commands can be embedded within a string with "$(command)" or using backquotes to quote the command. echo "hello `whoami`" echo "hello "$(whoami)

Question 26

what does the man command do ?

Answer 26

the man manual command provides information about commands. man date gives you more information about the man command

Question 27

Interpreting command syntax in man pages: what is []

Answer 27

Arguments are optional example: [+FORMAT]

Question 28

Interpreting command syntax in man pages: what is ...

Answer 28

Represents a list example: [file ...]

Question 29

Interpreting command syntax in man pages: what is |

Answer 29

or example: [-u|--utc|--universal]

Question 30

Interpreting command syntax in man pages: what is -

Answer 30

Any combination of available options in any order example: [ -hlwsqv]

Question 31

what is the whatis command used for ?

Answer 31

The whatis command is used to display a short description of the command.

Question 32

why is information for commands after installation not shown immediately

Answer 32

The whatis command uses a database for searching. Information may not be available for commands immediately after installation as the database is updated nightly.

Question 33

how to scroll command history

Answer 33

Up and down arrow key

Question 34

Repeat a command by the command history number

Answer 34

!n

Question 35

Repeat the last command.

Answer 35

!!

Question 36

how to display a list of commands executed

Answer 36

run the history command

Question 37

how to logout from account

Answer 37

logout command

Question 38

how to logout from shell

Answer 38

exit command

Question 39

how to add user in linux

Answer 39

adduser guest

Question 40

difference between su - guest and su guest

Answer 40

The difference between "su guest" and "su - guest" is that the latter includes the option "-". The "-" option is used to switch to the new user and also to change to that user's home directory, and it also execute the target user's profile and environment files.