Ubuntu Interview Questions for freshers experienced :-
1. What is Ubuntu ?
Ubuntu is a computer operating system based on the Debian Linux distribution and distributed as free and open source software, using its own desktop environment. It is named after the Southern African philosophy of ubuntu (“humanity towards others”).Ubuntu is designed primarily for use own personal computers, although a server edition also exists.
2. Why Ubuntu is safe and not affected by viruses?
- It does not support malicious e-mails and contents, and before any e-mail is opened by users it will go through many security checks
- Ubuntu uses Linux , which is a super secure O.S system
- Unlike other O.S, countless Linux users can see the code at any time and can fix the problem if there is any
Generally, Malwares and viruses are coded to take advantage of weakness in Windows
3. What is Unity in Ubuntu ? How can you add new entries to the launcher?
- In Ubuntu, Unity is the default windows manager. On left side of the Ubuntu it introduces the launcher and Dash to start programs.
- In order to add new entries to the launcher you can create a file name like .desktop and then drag file on the launcher.
4. How to enable root loging in Ubuntu?
The command which enables root loging is
#sudo sh-c ‘echo “greater-show-manual-login=true” >>/etc/lightdm/lightdm.conf’
5. How to enable startup sound in Ubuntu?
To enable startup sound in Ubuntu
Click control gear and then click on Startup Applications
In the Startup Application Preferences window, click Add to add an entry
Then fill the information in comment box like Name, Command and Comment
/usr/bin/canberra-gtk-play—id= “desktop-login”—description= “play login sound”
Logout and then login once you are done
6. How you can reset Unity Configuration?
To reset the unity configuration the simplest way to do is to hit open a Terminal or hit Atl-F2 and run the command # unity –reset
7. How to access Terminal?
To access terminal , you have to go under Application Menu -> Accessories -> Terminal .
You can also open it with shortcut key Ctrl+Alt+T.
8. How you can create a folder in Ubuntu using Terminal?
To create a folder in Ubuntu, you have to use command mkdir. It will be something like these : ~$ mkdir Ubuntu_rules
9. How you can view the text file in Ubuntu using Terminal?
To view the text file in Ubuntu, go to the specific folder where the text files are located by using the command cd and then type less filename.txt.
10. How to enable curl on Ubuntu LAMP stack?
To enable curl on Ubuntu , first install libcurl, once done use following command sudo/etc/init .d /apache2 restart or sudo service apache2 restart.
11. How you can find a file in Ubuntu using Terminal?
To find a file in Ubuntu you have to use command, find . –name “process.txt” . It will look for the current directory for a file called process.txt.
12. What is the quicker way to open an Ubuntu terminal in a particular directory?
To open Ubuntu terminal in a particular directory you can use custom keyboard short cut. To do that, in the command field of a new custom keyboard , type genome – terminal – – working – directory = /path/to/dir.
13. What is the meaning of “export” command in Ubuntu?
Export is a command in Bash shell language, when you try to set a variable, it is visible or exported to any subprocess started from that instance of bash. The variable will not exist in the sub-process without the export command.
14. How to uninstall the libraries in Ubuntu?
To uninstall the libraries in Ubuntu, you can use command sudo apt – get remove library_name
15. How you can run an Ubuntu program in the background simultaneously when you start your Ubuntu Server?
By using nohup. It will stop the process receiving the NOHUP signal and thus terminating it you log out of the program which was invoked with. & runs the process in the background.
16. How you can get the current color of the current screen on the Ubuntu desktop?
You can open the background image in The Gimp (image editor) and then use the dropper tool to select the color on the specific point. It gives you the RGB value of the color at that point.
17. What is the purpose of using libaio package in Ubuntu?
Libaio is Linux Kernel Asynchronous I/O (A/O). A/O allows even a single application thread to overlap I/O operations with other processing, by providing an interface for submitting one or more I/O requests in one system call without waiting for completion. And a separate interface to reap completed I/O operations associated with a given completion group.
18. How you create launchers on desktop in Ubuntu?
To create launchers on desktop in Ubuntu you can use
ALT+F2 then type “ gnome-desktop-item-edit –create-new~/desktop “, it will launch the old GUI dialog and create a launcher on your desktop
19. How to color the Git console in Ubuntu?
To color the Git console in Ubuntu you can use the command git config—global color.ui auto. In the command, the color.ui variable sets the default value for variable such as color.diff and color.grep.
20. How you can append one file to another in Ubuntu Linux?
To append one file to another in Ubuntu Linux you can use command cat file2 >> file 1. The operator >> appends the output of the named file or creates the file if it is not created. While another command cat file 1 file 2 > file 3 appends two or more files to one.
21. What is the use of behaviour tab in Ubuntu?
Through behaviours tab you can make many changes on the appearance of desktop
- Auto hide the launcher : You can use this option to reveal the launcher when moving the pointer to the defined hot spot.
- Enable workspaces: By checking this option you can enable workspace
- Add show desktop icon to the launcher: This option is used to display the desktop icon on the launcher
22. What is the command to calculate the size of a folder?
To calculate the size of a folder use the command du –sh folder1.
23. What is a folder in Ubuntu ?
There is no concept of Folder in Ubuntu. Everything including your hardware is a FILE
24. How can you find status of a process using Ubuntu ?
Use the command
ps ux
25. How can you check the memory status ?
You can use the command
free -m to display output in MB
free -g to display output in GB
26. What Components Have Been Released By Ubuntu For Their For Their Cloud Strategy?
Ubuntu till date has released three components, they are named as :
- Ubuntu Server Edition on Amazon EC2 (IaaS)
- Ubuntu enterprise cloud powered by Eucalyptus (IaaS)
- UbuntuOne(SaaS)
- The first two components are targeted for the infrastructure layer of the computer stack. And
- UbuntuOne is meant for the software layer also known as Software as a service (SaaS).
27. List Out A Few Of The Uses Of The Private Cloud Concept:
The private cloud concept has a variety of usage scenarios. Some of them are :
It enables an organization to rapidly develop and also prototype cloudware applications. Also this can be done behind a firewall enabling the creation/development of privacy sensitive applications such as classified data handling.
Being an elastic platform it enables the use of high performance applications whose load can be fluctuating. The system is based on aggregated peak loads of different applications at a single point of time.
By using private cloud concept the organization can assign a pool of hardware inside the firewall henceforth enabling it to be assigned to the users by a common gui to speed up the process.
UNIX/XENIX Interview Questions
28. What Does Private Cloud Offer In Building An Infrastructure?
Private cloud offers complete set of development tools and easy to configure panel where you can customize and deploy prototype applications.
- It keeps the private sensitive application separate and hidden from the world.
- It provides the provision to create high performance applications and include the concept of elasticity.
- It uses a firewall and keeps all the resources in a pool that separates them with other resources that are made public.
29. What Are Elements Included In Ubuntu Cloud Architecture?
The elements that are included in ubuntu cloud architecture are:
- Cloud controller: it is the main controller that controls the communication between two nodes and allows the system to communicate with each other.
- Walrus Storage controller: It controls the storage of the data and resource at one place for easy access.
- Elastic block storage controller: it uses the elasticity concept and allow the resources to scale up as the demand rises. This block consists of dynamic resources.
- Cluster controller: it controls the cloud clusters which are made up of mady nodes and contains the configuration of all the nodes from a single point.
- Node controller: it consists of the hardware resources that is being provided to the web or to the user through cluster controller.
30. What is The Function Of Walrus Storage Controller?
Walrus storage controller uses SOAP API that are compatible with its architecture.
Its main function is:
- To store the machine images that can be used by the cloud controller
- To access and store the data from anywhere.
- It provides file level storage system and doesn’t provide the locking of a file. It doesn’t allow concurrent file to change the status of a single file that is getting modified by the user.
- It saves the state of the images.
31. What Are The Tasks Performed By Node Controller?
Node controller consists of the hardware settings and configuration for the image machines. It performs the tasks that are requested by cluster controller and reply to the queries.
It performs the following tasks:
- Verify and authenticate the user request.
- Allow user to download the image from the cache and use it.
- Create a virtual network interface for easy communication between machines.
- Start an instance of a virtual machine that can be accessed by the user.
32. What Was The Requirement Of The Initial Addition Of Node Controller?
The initial addition of Node Controller required a password to exchange the cryptographic keys from the lower controller to the upper one. After the password is exchanged, all operations rely on the trust provided by these keys in the communications between the controllers.
33. How Does Networking Play An Important Role In Security?
To prevent eavesdropping on network traffic from a machine run by one user to the machines run by other users, networking plays an important role in security.
Following networking modes are available at set-up time, depending on the level of security:
- SYSTEM Mode
- STATIC Mode
- MANAGED Mode
- MANAGED-NOVLAN Mode
34. What are the Different Types Of Actors Involved In Authentication And Authorization?
There are two types of actors that are required for authentication and authorization:
User or administrator of the system who has the rights to start and stop the instances of the system.
Components of the systems that are required to be present to fully utilize the requests.
The authentication on ubuntu cloud is being performed by X509 certificate that consists of cryptographic keys for authentication and secure communications between all the actors.
35. What are the Steps Involved In Authenticating and Authorizing The User?
To authenticate and authorize the user there are two steps involved:
- User should have access to the cloud controller account and access to its user interface.
- Administrative rights to the user to create their own policies.
The registered users get a access key that gives the certificate and the query information to the user which can be used to authorize the user’s status.
The authentication will vary for each user to access the cloud and its service. To authenticate the user a password will be given to access the web console and retrieve their certificate and query key. Cloud controller verifies the authentication only at the first time but the authorization is verified at each level.
36. What are the Three Levels of Machine Instance isolation?
The three levels that are included in instance isolation:
Networking isolation: it keeps the overall security of the ubuntu cloud system and keeps the network isolated from the user sight so that there will be less security issues.
OS isolation: it keeps the user away from the operating system changes. It provides Mandatory Access control (MAC) system that includes default scripts to provide the isolation from the user to the Operating system.
Hypervisor based machine isolation: it doesn’t allow the user to know what kind of hypervisor is used to provide the services which users have asked for. It provides intrinsic properties to hide its existence from the users of the cloud.
37. What are the Features Included in Ubuntu Enterprise Cloud?
Ubuntu enterprise cloud includes many features that are not being provided with the other cloud platforms:
- It is EC2 compatible cloud platform that is built on ubuntu server.
- It provides complete built in cloud solution to manage the on-demand functionality.
- It provides the features of on-demand access and increases the EC2 functionality.
- It provides privacy policies and isolation from the hardware devices.
- It provides an easy way to scale the public providers and avoid lock-in whenever possible.
38. How to Identify Ethernet Interfaces in Ubuntu Cloud?
Ethernet interfaces are the part of the networking and it is automatically identified by the system using different naming conventions. It is represented by ethX, where X= any numeric value. The default interface of the system is named as eth0 and it will go on after this.
To identify the Ethernet interface the command that is used:
ifconfig -a | grep eth
eth0
Link encap:Ethernet
HWaddr 00:15:c5:4a:16:5aThe command will show all the interfaces that are associated with the system.
39. What are the Limitations/demerits of Ubuntu Cloud?
Cloud computing has a few disadvantages, some of them are:
Security and privacy: The data in ubuntu cloud have many instances with a third party which many users may not prefer. Cloud servers store sensitive information which must be protected at all costs. There is a vulnerability of unauthorized access.
Loss of control (dependency): In cloud computing the cloud service providers play a major role more maintenance and fixing of the cloud. Being a third party an organization has less control over it. And once a cloud is established migrating to another CSP is not an easy task.
Costs: Although in the long run cloud computing is cheap but being a new technology the improvements and research involved makes it quite expensive. To incorporate this technology many changes may be require including the development of software.
Integration and knowledge: As most of the functions are provided by a CSP getting to understand the system from an organizational point of view is tough. Also integration with existing systems is hard to achieve.
40. How ip addressing is Managed on Ubuntu Cloud?
The IP addressing is an essential part of networking and to establish an ubuntu cloud it has to be configured correctly and the default gateway has to be mentioned for communication with other network or same network. To configure the IP addressing the command that can be used is ip, ifconfig and route. These are the commands that allow the configuration of the networking.
To set the configuration use the following command:
sudo ifconfig eth0 10.0.0.100 netmask 255.255.255.0
Through this IP address can be set and configured temporarily to save it permanently ifconfig file has to be modified.
41. Whether your video card can run Unity how would you know?
When you use command /usr/lib/nux/unity_support_test-p it will give detailed output about Unity’s requirements and if they are met, then your video card can run unity.
42. How can I create launchers on my desktop?
The old GUI dialog is still available if you still want to use this:
Using ALT+F2 type ” gnome-desktop-item-edit –create-new ~/Desktop ”
This will launch the old GUI Dialog and create a launcher on your Desktop:
take the image from http://askubuntu.com/questions/64222/how-can-i-create-launchers-on-my-desktop
gnome-desktop-item-edit is installed automatically if you have installed gnome-shell/gnome-fallback. It is also installed automatically if you have previously installed gnome-tweak-tool.
Alternatively, you can install the old gnome-panel without much of the bulk:
sudo apt-get install –no-install-recommends gnome-panel