Basic C++ and Unix Questions and Answers - 14

C++ and Unix Operating System / OS Important mostly asked questions

1. Could you tell something about the Unix System Kernel? (from ITCO )
Ans. The kernel is the heart of the UNIX openrating system, it?s reponsible for controlling the computer?s resouces and scheduling user jobs so that each one gets its fair share of resources.

2. What are each of the standard files and what are they normally associated with? (from ITCO )
Ans. They are the standard input file, the standard output file and the standard error file. The first is usually associated with the keyboard, the second and third are usually associated with the terminal screen.

3. Detemine the code below, tell me exectly how many times is the operation sum++ performed ? (from ITCO )
for ( i = 0; i < 100; i++ )
for ( j = 100; j > 100 - i; j?)
sum++;
A3: (99 * 100)/2 = 4950
The sum++ is performed 4950 times.

4. Give 4 examples which belongs application layer in TCP/IP architecture? (from CISCO )
A4: FTP, TELNET, HTTP and TFTP

5. What?s the meaning of ARP in TCP/IP? (from CISCO )
A5: The "ARP" stands for Address Resolution Protocol. The ARP standard defines two basic message types: a request and a response. a request message contains an IP address and requests the corresponding hardware address; a replay contains both the IP address, sent in the request, and the hardware address.

6.What is a Make file?(Fujitsu)

Make file is a utility in Unix to help compile large programs. It helps by only compiling the portion of the program that has been changed.

7.What is deadlock? (Novell)

Deadlock is a situation when two or more processes prevent each other from running.Example: if T1 is holding x and waiting for y to be free and T2 holding y and waiting for x to be free deadlock happens.

8.What is semaphore? (Novell)

Semaphore is a special variable, it has two methods: up and down. Semaphore performs atomic operations, which means ones a semaphore is called it can not be inturrupted.

9.Is C an object-oriented language? (Microsoft)

C is not an object-oriented language, but limited object-oriented programming can be done in C.

10.Name some major differences between C++ and Java.

C++ has pointers; Java does not. Java is platform-independent; C++ is not. Java has garbage collection; C++ does not.

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Unix Technical Interview Questions 2008

Linux Admin Technical Interview Questions 4
Unix SQL Data Mining Interview Questions asked Latest 3
Open Source Linux Programming Interview Questions 2
Unix Linux Open Source OS Interview Questions 1

Unix / Linux Open Source Operating System and Applications - Technical Interview Questions for Developers and entry level or advanced designers for leading IT /ITES / Internet / Web 2.0 companies worldwide for recent 2007, 2008 placement papers for freshers / walkins or on campus interviews. Keep watching for more.

Linux Admin Technical Interview Questions

Interview questions for Linux admin

1. Advantages/disadvantages of script vs compiled program.

2. Name a replacement for PHP/Perl/MySQL/Linux/Apache and show main differences.

3. Why have you choosen such a combination of products?

4. Differences between two last MySQL versions. Which one would you choose and when/why?

5. Main differences between Apache 1.x and 2.x. Why is 2.x not so popular? Which one would you choose and when/why?

6. Which Linux distros do you have experience with?

7. Which distro you prefer? Why?

8. Which tool would you use to update Debian / Slackware / RedHat / Mandrake / SuSE ?

9. You’re asked to write an Apache module. What would you do?

10. Which tool do you prefer for Apache log reports?

11. Your portfolio. (even a PHP guest book may work well)

12. What does ‘route’ command do?

13. Differences between ipchains and iptables.

14. What’s eth0, ppp0, wlan0, ttyS0, etc.

15. What are different directories in / for?

16. Partitioning scheme for new webserver. Why?

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Unix SQL Data Mining Interview Questions asked latest

Unix sysadmin interview questions

1. How would you make the following SQL statement run faster? SELECT * FROM TABLEA WHERE COL1=’A’ AND COL2=’B';
A: Make sure that COL1 and COL2 have indexes.
Find out which condition will return less values and use that as the first conditonal.

2. What is Data Mining
A: Data Minig is the process of sifting through extremeley large amounts of Data to find trends or relevent information.

3. Name the Seven layers in the OSI Model.
A: Appication, Presentation, Session, Transport, Network, Data Link, Phyiscal

4. What is one way to view a unix network share on a Windows computer, within explorer
A: NFS, The Unix computer can be running a NFS Server Daemon.

5. How would you find all the processes running on your computer.
A: Unix, is ps -ef or ps -aux depending on version.

6. What is DHCP
A: DHCP is a way to dynamically assign IP address to computers. Dyanmic Host Configuration Protocol

7. What is HTTP Tunneling
A: HTTP Tunneling is a security method that encryptes packets traveling throught the internet. Only the intended reciepent should be able to decrypt the packets. Can be used to Create Virtual Private Networks. (VPN)

8. Scenario: You have 9 identical looking balls, however one ball is heavier than the others. You have two chances to use a balance. How do you find out which ball is the heaviest?
A: Split into groups of three, randomly choose two groups and use balance on them. If one group is heavier, then discard the other 6 balls. If the two groups are the same weight. The heavier ball must be in the group that was not on the scale. Now randomly choose two balls and test on balance. If they are the same weight, the heaviest ball is on one that was not tested. Else the heaviest ball is already known from the balance

Open Source Linux Programming Interview Questions

Unix and Linux Software programming Interview Questions 2008

1. What is the major advantage of a hash table? (Asked by Silicon Magic Corp. people) Answer: The major advantage of a hash table is its speed. Because the hash function is to take a range of key values and transform them into index values in such a way that the key values are distributed randomly across all the indices of a hash table.

2. What are the techniques that you use to handle the collisions in hash tables?(Asked by Silicon Magic Corp. people)

Answer: We can use two major techniques to handle the collisions. They are open addressing and separate chaining. In open addressing, data items that hash to a full array cell are placed in another cell in the array. In separate chaining, each array element consist of a linked list. All data items hashing to a given array index are inserted in that list.

3. In Unix OS, what is the file server? (Asked by Silicon Magic Corp. people)

Answer: The file server is a machine that shares its disk storage and files with other machines on the network.

4. What is NFS? What is its job?(Asked by Silicon Magic Corp. people)

Answer: NFS stands for Network File System. NFS enables filesystems physically residing on one computer system to be used by other computers in the network, appearing to users on the remote host as just another local disk.

5. What is CVS? List some useful CVS commands.(Asked by Silicon Magic Corp.people)

Anser: CVS is Concurrent Version System. It is the front end to the RCS revision control system which extends the notion of revision control from a collection of files in a single directory to a hierarchical collection of directories consisting of revision controlled files. These directories and files can be combined together to form a software release.
There are some useful commands that are being used very often. They are

cvs checkout
cvs update
cvs add
cvs remove
cvs commit

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Unix Linux Open Source OS Interview Questions

Unix / Linux Operating System progamming Interview Questions

1.What is LILO?

LILO stands for Linux boot loader. It will load the MBR, master boot record, into the memory, and tell the system which partition and hard drive to boot from.

2.What is the main advantage of creating links to a file instead of copies of the file?

A: The main advantage is not really that it saves disk space (though it does that too) but, rather, that a change of permissions on the file is applied to all the link access points. The link will show permissions of lrwxrwxrwx but that is for the link itself and not the access to the file to which the link points. Thus if you want to change the permissions for a command, such as su, you only have to do it on the original. With copies you have to find all of the copies and change permission on each of the copies.

3.Write a command to find all of the files which have been accessed within the last 30 days.

find / -type f -atime -30 > December.files

This command will find all the files under root, which is ‘/’, with file type is file. ‘-atime -30′ will give all the files accessed less than 30 days ago. And the output will put into a file call December.files.

4.What is the most graceful way to get to run level single user mode?

A: The most graceful way is to use the command init s.
If you want to shut everything down before going to single user mode then do init 0 first and from the ok prompt do a boot -s.

5.What does the following command line produce? Explain each aspect of this line.

$ (date ; ps -ef awk ‘{print $1}’ sort uniq wc -l ) >> Activity.log

A: First let’s dissect the line: The date gives the date and time as the first command of the line, this is followed by the a list of all running processes in long form with UIDs listed first, this is the ps -ef. These are fed into the awk which filters out all but the UIDs; these UIDs are piped into sort for no discernible reason and then onto uniq (now we see the reason for the sort - uniq only works on sorted data - if the list is A, B, A, then A, B, A will be the output of uniq, but if it’s A, A, B then A, B is the output) which produces only one copy of each UID.

These UIDs are fed into wc -l which counts the lines - in this case the number of distinct UIDs running processes on the system. Finally the results of these two commands, the date and the wc -l, are appended to the file "Activity.log". Now to answer the question as to what this command line produces. This writes the date and time into the file Activity.log together with the number of distinct users who have processes running on the system at that time. If the file already exists, then these items are appended to the file, otherwise the file is created.