Linux Environment Variables and Shell Scripting

Question 1

how to display a list of all the env variables

Answer 1

printenv or env

Question 2

what does echo $HOME do

Answer 2

The absolute path of the home directory

Question 3

what does echo $PATH

Answer 3

The value of the command search path.

Question 4

what does echo $PS1 RETURN

Answer 4

The value of the primary prompt.

Question 5

what does echo $PS2 RETURN

Answer 5

The value of the secondary prompt

Question 6

what does echo $PWD RETURN

Answer 6

The absolute path of the current work directory.

Question 7

WHAT DOES echo $SHELL RETURN

Answer 7

The absolute path of the login shell.

Question 8

WHAT DOES echo $USER RETURN

Answer 8

name of current user logged in

Question 9

Two processes connected by a pipe run in ________

Answer 9

parallel

Question 10

what does ls | wc mean

Answer 10

ls is the producer

wc is the consumer of this output

Question 11

how to look for all txt files

Answer 11

ls | grep txt

Question 12

how to count number of lines in linux

Answer 12

wc -l

Question 13

how to count number of characters in linux

Answer 13

wc -m

Question 14

how to count number of bytes in linux

Answer 14

wc -c

Question 15

how to view contents of a file

Answer 15

cat filename

Question 16

how to read input from key board and save to file

Answer 16

cat > filename

ctrl + d to stop

Question 17

how to sort data in file

Answer 17

sort < filename

Question 18

how to append output to a file

Answer 18

echo world&raquo_space; filename

Question 19

sort the file and save the output to another file

Answer 19

sort < data.txt > sortedData.txt

Question 20

what does output 116 mean when wc cmd is used

Answer 20

1 line
1 word
6 bytes

Question 21

what does cat hello.txt 1>data.bak 2>error.txt

Answer 21

if cat hello.txt has no error the output will be saved to data.bak

else it will be saved to error.txt

Question 22

how to quote meta characters

Answer 22

-using backslash (): echo \; hello
-using single quote (‘) echo ‘;hello’
-using double quote (“) echo “;hello”

Question 23

how to return “today’s date is 29 feb 2022”

Answer 23

echo “today’s date is $DATE”

or

echo “today’s date is DATE”

Question 24

make a name variable equal to student

Answer 24

NAME=student

echo $NAME (for checking)

Question 25

create an array FRUITS with
apple
green apple
orange

Answer 25

FRUITS[0]=apple
FRUITS[1]=”green apple”
FRUITS[2]=orange

echo ${FRUITS[*]}
or
echo ${FRUITS[@]}

Question 26

how to check length of the array

Answer 26

echo ${#FRUITS[@]}

Question 27

make an array with multiple values in 1 cmd

Answer 27

FRUIT_BASKET=(kiwi “dragon fruit” pear)

Question 28

make an array with specific index values

Answer 28

FRUIT_BASKET=([10]=kiwi [1]=”dragon fruit” [3]=pear)

Question 29

create 2 variables a and b and do a division using them

Answer 29

echo $(($a/$b))

Question 30

create a sales report and chart using brace expansion having the year and month

Answer 30

echo sales_{report, chart}_${date +%Y%m}

Question 31

how to check hostname

Answer 31

hostname

Question 32

how to check hostname and date on the same line

Answer 32

hostname; date

Question 33

write the hostname and date data to a fiel

Answer 33

(hostname; date) > file.txt

Question 34

create a hello.sh file with a hello variable

Answer 34

#!/bin/bash (specifies the shell to use to execute the script )
HELLO=”hello”
echo $HELLO

Question 35

!/bin/bash

echo “What is your name?”
read NAME
echo “hello” $NAME

what does this do

Answer 35

allows users to key in their name and will return

hello karthik

Question 36

Can you execute the script by “hello.sh” without specifying the path?

Answer 36

yes, Enter “PATH=:$PATH”and press enter

an empty entry means current directory