Basic linux interview questions

1)How do you find out what’s your shell? – echo $SHELL
2)What’s the command to find out today’s date? – date

 

3)How do you find out the current directory you’re in? – pwd

4)How do you find out your own username? – whoami/who am i

5)How do you send a mail message to somebody? – mail surendra@linuxnix.com -s ‘Your subject’ -c ‘test@gmail.com‘

 

6)What’s the command to find out users on the system? – who/users

7)How do you remove a file? – rm

8)How do you remove a – rm -rf

9)How do you count words, lines and characters in a file? – wc

10)How do you search for a string inside a given file? – grep string filename

 

11)How do you search for a string inside a directory? – grep string *

12)How do you search for a string in a directory with the subdirectories recursed? – grep -r string *

13)What are PIDs? – They are process IDs given to processes. A PID can vary from 0 to 65535.

14)How do you list currently running process? – ps

15)How do you stop a process? – kill pid

 

16)How do you find out about all running processes? – ps -ag

17)How do you stop all the processes, except the shell window? – kill 0

18)How do you fire a process in the background? – ./process-name &

19)How do you refer to the arguments passed to a shell script? – $1, $2 and so on. $0 is your script name.

20)What’s the conditional statement in shell scripting? – if {condition} then … fi

 

21)How do you do number comparison in shell scripts? – -eq, -ne, -lt, -le, -gt, -ge

22)How do you test for file properties in shell scripts? – -s filename tells you if the file is not empty, -f filename tells you whether
the argument is a file, and not a directory, -d filename tests if the argument is a directory, and not a file, -w filename tests for writeability, -r filename tests for readability, -x filename tests for excitability

23)How do you do Boolean logic operators in shell scripting? – ! tests for logical not, -a tests for logical and, and -o tests for logical or.

24)How do you find out the number of arguments passed to the shell script? – $#

25)What’s a way to do multilevel if-else’s in shell scripting? – if {condition} then {statement} elif {condition} {statement} fi

26)How do you write a for loop in shell? – for {variable name} in {list} do {statement} done

 

27)How do you write a while loop in shell? – while {condition} do {statement} done

28)How does a case statement look in shell scripts? – case {variable} in {possible-value-1}) {statement};; {possible-value-2}) {statement};; esac

29)How do you read keyboard input in shell scripts? – read {variable-name}

30)How do you define a function in a shell script? – function-name() { #some code here return }

31)How does getopts command work? – The parameters to your script can be passed as -n 15 -x 20.Inside the script, you can iterate through the getopts array as while getopts n:x option, and the variable $option contains the value of the entered option.

		 

 

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Surendra Anne

Mr Surendra Anne is from Vijayawada, Andhra Pradesh, India. He is a Linux/Open source supporter who believes in Hard work, A down to earth person, Likes to share knowledge with others, Loves dogs, Likes photography. He works as Devops Engineer with Taggle systems, an IOT automatic water metering company, Sydney . You can contact him at surendra (@) linuxnix dot com.

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