Unix/Linux Interview Questions and Answers

What is relative path and absolute path?
Absolute path : Exact path from root directory. Relative path : Relative to the current path.
How to count number char, line in a file?
by using wc-stands for word count. wc -c for counting number of characters in a file. wc -l for counting lines in a file.
What is du command do?

With the help of this command you can find the disk capacity and free space of the disk.

What is the use of the command 'ls -x chapter[1-5]'?
ls stands for list; so it displays the list of the files that starts with 'chapter' with suffix '1' to '5', chapter1, chapter2, and so on.

What will the following command do?
$echo *

It is similar to 'ls' command and displays all the files in the current directory.

Which command is used to delete all files in the current directory and all its sub-directories?
rm -r *

What is the use of "grep" command?

grep (Global Regular Expression Print) is a pattern search command. It searches for the pattern, specified in the command line with appropriate option, in a given file(s).
Syntax : grep [options] pattern [files]
Example : grep 99mx mcafile

What is a pipe and give an example?
Unix commands alone are powerful, but when you combine them together, you can accomplish complex tasks with ease. The way you combine Unix commands is through using pipes and filters. The symbol | is the Unix pipe symbol that is used on the command line. What it means is that the standard output of the command to the left of the pipe gets sent as standard input of the command to the right of the pipe. However, the pipe is different because it is used to pass the output of a command to another command- example: $ cat apple.txt | wc
What is the difference between cat and more command?
"Cat" displays file contents. If the file is large the contents scroll off the screen before we view it. So command "more" is like a pager which displays the contents page by page.

How do display the 10th, 11th and 12th line of a file in Unix?

Combining the two commands head and tail can give you the result -

$ head -12 <filename> | tail -3
Ex -

$ head -12 test.txt | tail -3

What is nohup command in unix?

Nohup stands for no hang up. It is a Unix command that is used to run another command. It tells Unix not to stop passed command once it has started, that will keep running until done.
When you execute a Unix job in the background( &, bg command), and logout from the session, then that process will get killed. It can avoid this by executing the job with nohup.
Nohup prevents the command from being aborted automatically when you log out or exit the shell.

# nohup sample.sh &

By default, standard output will be redirected to nohup.out file in the current directory. You can also redirect the output to an other file using the normal shell redirection.

# nohup sh sample.sh > sample-out.log &

Once a job is started or executed using the nohup command, stdin will not be available to the user.

What is inode?

An inode is a unique entry which by default gets created on a disk section for a file system. It contains the following information:

Location on the disk
User of the file
Size of the file
Group of the file
Device ID
File size
Date of creation
Owner of the file

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Apache Tomcat

What is the difference between Apache Tomcat server and Apache web server?


What is the full form of DOS?

Explain the use of help DOS Command?

How we can create a directory in DOS?






Pipes and Cistern

A tank can be filled by one tap in 10 minutes and by another in 30 minutes. Both the taps are kept open for 5 minutes and then the first one is shut off. In how many minutes more is the tank completely filled?


Assume that a sum of money is divided equally among n girls. Each girl will receive $60. If another girl is added to the group and the sum is divided equally among all the girls, each child girl gets a $50 share. What is the sum of money?

Problems on Trains

A 300 meter long metro train crosses a platform in a metro station in 39 seconds while it crosses a lamp post in 18 seconds. What is the length of the platform?

Problems on Ages

In a group of 7 people, the average age is found to be 17 years. Two more people joined with an average age 19 years. One person left the group whose age was 25 years. What is the new average age of the group?

Profit and Loss

Irvin sold a book at a profit of 12%. If Irvin had sold it for Rs 18 more, then 18% would have been gained. Find the cost price?


Non stick cooking utensils are coated with?

The group of metals Co, Ni, Fe may best called as?

General Knowledge of India

'Kanchipuram' is in which of the following states?

General Knowledge of World

In which year was Pulitzer Prize established?

Indian History

The roads of cities in the Indus Valley Civilization generally divided the city into?

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