Operational Bash Arithmetic Expressions Interview Questions & Answers:

1. Which built-in command performs integer arithmetic in bash shell?
a) let
b) get
c) set
d) none of the mentioned

a) let

2. Which expression use the value of the enclosed arithmetic expression?
a) $(())
b) $()
c) ${}
d) $[]

a) $(())

3. If a and b are 2 variables then the meaning of a<<=b is:
a) b = a << b
b) a = a << b
c) b = b << a
d) a = a << b

b) a = a << b

4. Which one of the following is bit-wise 'exclusive or' operator?
a) ^=
b) |=
c) !=
d) none of the mentioned

a) ^=

5. Which one of the following is not a valid operator in bash shell?
a) ||
b) ~
c) =<<
d) -=

c) =<<

6. What is the output of this program?
If:
1) #!/bin/bash
2) a=2
3) b=4
4) let c=a**b
5) echo $c
6) exit 0

Options:
a) 8
b) 16
c) 32
d) none of the mentioned

b) 16

Explanation:
'**' is the exponentation operator in bash shell.
Output:
root@ubuntu:/home/google#./test.sh
16
root@ubuntu:/home/google#

7. What is the output of this program?
#!/bin/bash
a=10; b=20
c=$((++a))
let a=c+a
echo $a
exit 0
a) 21
b) 22
c) program will generate an error message
d) none of the above

b) 22

8. What is the output of this program?
#!/bin/bash
a=10
b=$(( $a<0?10:$a<100 ))
echo $b
exit 0
a) 10
b) 20
c) 1
d) 0

c) 1
Firstly the '$a<0' condition has been checked. Because it is false hence the right hand side condition of the colon (:) has been checked and this is true so program output is 1.

9. What is the output of this program?
#!/bin/bash
a=10
b=$(( $a<0&&$a<100 ))
echo $b
exit 0
a) 10
b) 0
c) 1

b) 0
The condition '$a<0' is false so logical and operator provides the output 0.

10. What is the output of this program?
#!/bin/bash
a=1; b=2; c=3
d=$(( ++a**b*c++ + a ))
echo $d
exit 0

a) 14
b) 12
c) program will generate an error message
d) none of the mentioned

a) 14
The operators in decreasing order of precedence are ++, **, *, +.

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11. Which command sets up shorthand for command or command line?
a) set
b) alias
c) new
d) echo

b) alias

12. What is the function of bind command in bash shell?
a) defining new macros
b) defining new key bindings for existing commands
c) dumping the installed key bindings
d) all of the mentioned

d) all of the mentioned

13. The command 'compgen -c' shows:
a) all variable names
b) all system wide aliases
c) full list of all commands
d) none of the mentioned

c) full list of all commands

14. Which statement resumes the next iteration of a for, while, select, or until loop?
a) continue
b) break
c) complete
d) command

a) continue

15. Which command prints the directory stack?
a) cd
b) dirs
c) popd
d) pushd

b) dirs

16. The command 'disown -r':
a) removes all jobs
b) removes all running jobs
c) marks jobs to not receive SIGNUP when bash exits
d) marks all jobs

b) removes all running jobs

17. The command 'enable -n ':
a) enables the specified built-in command
b) disables the specified built-in command
c) print the status of the command
d) none of the mentioned

b) disables the specified built-in command

18. Which command can create environment variable?
a) export
b) set
c) read
d) none of the mentioned

a) export

19. Which command concatenate the specified argument into a single command, then execute the command?
a) fc
b) eval
c) exec
d) getopts

b) eval

20. The command 'hash':
a) manages a internal hash table
b) find and remember the full path name of the specified command
c) displays used command names and the number of hits
d) all of the mentioned

d) all of the mentioned

21. Which command runs the shell built-in command 'command' with the given argument?
a) builtin
b) caller
c) there is no command present for this purpose
d) none of the mentioned

a) builtin

22. After running this program, if you enter 1000, then what will be the output of the program?
#!/bin/bash
echo "Please enter a number"
read a
if [ $a -lt 100 ]; then
echo "It is less than 100";
elif [ $a -lt 1000 ]; then
echo "It is less than 1000"
else
echo "It is greater than 1000"
fi
exit 0
a) It is greater than 1000
b) It is less then 1000
c) It is equal to 1000
d) none of then mentioned

a) It is greater than 1000

23. What is the output of this program?
#!/bin/bash
echo "Which file do you want to check"
read x
until [ -e $x ]
do
echo "The file does not exist. Do you want to create? y/n"
read a
if [ $a = y ]; then
touch $x
echo "Your file has been created successfully."
fi
done
echo "The file is present in this directory"
exit 0

a) it checks the existance of your entered file in the present working directory
b) it creates the file if file does not exists
c) program runs untill you create the file
d) all of the mentioned

d) all of the mentioned

24. How can you come out of the loop in this program?
#!/bin/bash
read x
while [ $x != "hello" ]
do
echo "Try to come out of the loop"
read x
done
echo "Welcome"
exit 0
a) by entering "hello"
b) by entering anything except "hello"
c) it is not possible
d) none of the mentioned

a) by entering "hello"

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25. What is the output of this program?
#!/bin/bash
for i in 2 3 7
do
echo "ggl"
done
exit 0
a) 'ggl' will print 3 times
b) nothing will print
c) program will generate an error message
d) none of the mentioned

a) 'ggl' will print 3 times