Q:1 What is Linux ?

Ans: Linux is an operating system based on UNIX, and was first introduced by Linus Torvalds. It is based on the Linux Kernel, and can run on different hardware platforms manufactured by Intel, MIPS, HP, IBM, SPARC and Motorola.


Ans: Unix originally began as a propriety operating system from Bell Laboratories, which later on spawned into different commercial versions. On the other hand, Linux is free, open source and intended as a non-propriety operating system for the masses.

Q:3 What is BASH?

Ans: BASH is short for Bourne Again SHell. It was written by Steve Bourne as a replacement to the original Bourne Shell (represented by /bin/sh). It combines all the features from the original version of Bourne Shell, plus additional functions to make it easier and more convenient to use. It has since been adapted as the default shell for most systems running Linux.

Q:4 What is Linux Kernel?

Ans: The Linux Kernel is a low-level systems software whose main role is to manage hardware resources for the user. It is also used to provide an interface for user-level interaction.

Q:5 What is LILO?

Ans: LILO is a boot loader for Linux. It is used mainly to load the Linux operating system into main memory so that it can begin its operations.

Q:6 What is the advantage of open source?

Ans: Open source allows you to distribute your software, including source codes freely to anyone who is interested. People would then be able to add features and even debug and correct errors that are in the source code. They can even make it run better, and then redistribute these enhanced source code freely again. This eventually benefits everyone in the community.

Q:7 What is umask ?

Ans: umask stands for ‘User file creation mask’, which determines the settings of a mask that controls which file permissions are set for files and directories when they are created.

Q:8 How to set the umask permanently for a user?

Ans: To set this value permanently for a user, it has to be put in the appropriate profile file which depends on the default shell of the user.

Q:9 How to change the default run level in linux ?

Ans: To change the run level we have to edit the file “/etc/inittab” and change initdefault entry ( id:5:initdefault:). Using ‘init’ command we change the run level temporary like ‘init 3’ , this command will move the system in runlevl 3.

Q:10 How to share a directory using nfs ?

Ans: To share a directory using nfs , first edit the configuration file ‘/etc/exportfs’ , add a entry like ‘/ (Options)’ and then restart the nfs service.

Q:11 What are the default ports used for SMTP,DNS,FTP,DHCP,SSH and squid ?

Ans: Service Port
SMTP   25
DNS     53
FTP      20 (data transfer) , 21 ( Connection established)
DHCP   67/UDP(dhcp server) , 68/UDP(dhcp client)
SSH        22
Squid     3128