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UNIX INTERVIEW QUESTIONS ANSWERS PDF

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Linux, Windows etc. Here I have collected UNIX interview questions with their answers for your reference. If you require download UNIX Faqs in PDF format. UNIX command Questions Answers asked in Interview. UNIX or Linux operating system has become default Server operating system and for whichever. It is intended as a tutorial on the Unix, and commonly asked qestions in all interviews. Contains Important Unix Interview Questions with Answers and Unix FAQs.


Unix Interview Questions Answers Pdf

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unix interview questions with answers, unix shell scripting interview questions, unix commands, General UNIX interview questions, Some UNIX Interview. what is unix, unix shell, steps UNIX shell follows while processing a command, cmp & diff in UNIX, grep command, cat & more UNIX prompts. Unix and Linux Command Interview Questions and Answers .. I download all these UNIX interview questions and answers in PDF format?.

This symbol tells your shell to execute the given command in the background. How do you execute one program from within another? Ans: The system calls used for low-level process creation are execlp and execvp. The execlp call overlays the existing program with the new one , runs that and exits.

The original program gets back control only when an error occurs. What is IPC? What are the various schemes available? Ans: The term IPC Inter-Process Communication describes various ways by which different process running on some operating system communicate between each other. Various schemes available are as follows: Pipes: One-way communication scheme through which different process can communicate.

The problem is that the two processes should have a common ancestor parent-child relationship. However this problem was fixed with the introduction of named-pipes FIFO. Message Queues : Message queues can be used between related and unrelated processes running on a machine. The memory to be shared is mapped into the address space of the processes that are sharing. The speed achieved is attributed to the fact that there is no kernel involvement. But this scheme needs synchronization.

You can also use rsync command to answer this UNIX interview question or even sftp would be ok. How do you find which process is taking how much CPU? How do you check how much space left in current drive? By using "df" command in UNIX. For example "df -h. This is part of anyone day to day activity so I think this Unix Interview question will be to check anyone who claims to working in UNIX but not really working on it.

What is the difference between Swapping and Paging? Whole process is moved from the swap device to the main memory for execution.

Process size must be less than or equal to the available main memory. It is easier to implementation and overhead to the system. Swapping systems does not handle the memory more flexibly as compared to the paging systems.

Only the required memory pages are moved to main memory from the swap device for execution. Process size does not matter. Gives the concept of the virtual memory. It provides greater flexibility in mapping the virtual address space into the physical memory of the machine.

Allows more number of processes to fit in the main memory simultaneously.

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Allows the greater process size than the availablephysical memory. Demand paging systems handle the memory more flexibly. What is difference between ps -ef and ps -auxwww? This is indeed a good Unix Interview Command Question and I have faced this issue while ago where one culprit process was not visible by execute ps —ef command and we are wondering which process is holding the file.

How do you find how many cpu are in your system and there details?

When a program forks and the child finishes before the parent, the kernel still keeps some of its information about the child in case the parent might need it - for example, the parent may need to check the child's exit status. The process is dead but have not been removed from the process table. What is "chmod" command? In a file word UNIX is appearing many times?

How will you count number? How do you set environment variable which will be accessible form sub shell? How do you check if a particular process is listening on a particular port on remote host? How do you find whether your system is 32 bit or 64 bit?

Either by using "uname -a" command or by using "arch" command.

General UNIX interview questions with answers

How do you find which processes are using a particular file? By using lsof command in UNIX. It wills list down PID of all the process which is using a particular file. How do you find which remote hosts are connecting to your host on a particular port say ? By using netstat command execute netstat -a grep "port" and it will list the entire host which is connected to this host on port What is ephemeral port in UNIX?

Ephemeral ports are port used by Operating system for client sockets. There is a specific range on which OS can open any port specified by ephemeral port range.

If one process is inserting data into your MySQL database? How will you check how many rows inserted into every second? Purpose of this Unix Command Interview is asking about "watch" command in UNIX which is repeatedly execute command provided with specified delay. You have a tab separated file which contains Name, Address and Phone Number, list down all Phone Number without there name and Addresses?

CUT use tab as default separator so you can use cut -f3 filename. Your application home directory is full? How will you find which directory is taking how much space?

By using disk usage DU command in Unix for example du —sh. How do you find for how many days your Server is up? By using uptime command in UNIX You have an IP address in your network how will you find hostname and vice versa? This is a standard UNIX command interview question asked by everybody and I guess everybody knows its answer as well. These are very basic unix commands and you must know these commands if you are going to appear in a unix interview.

I have listed down 31 unix interview questions with answers which cover basic unix commands like ls, banner, cat, date, tee, who, man, head, pg, cmp, diff, grep, kill, echo, su etc. So lets have a look on following unix interview questions and commands. Construct pipes to execute the following jobs. Output of who should be displayed on the screen with value of total number of users who have logged in displayed at the bottom of the list. Contents of file1 and file2 should be displayed on the screen and this output should be appended in a file.

Name of cities should be accepted from the keyboard. This list should be combined with the list present in a file. Explain the following commands. It reads the standard input and sends it to the standard output while redirecting a copy of what it has read to the file specified by the user. The input from a pipe can be combined with the input from a file. In the above command the output from who becomes the std input to sort , meanwhile sort opens the file logfile, the contents of this file is sorted together with the output of who rep by the hyphen and the sorted output is redirected to the file newfile.

Which of the following commands is not a filter man , b cat , c pg , d head Ans: Explain the steps that a shell follows while processing a command. After the command line is terminated by the key, the shell goes ahead with processing the command line in one or more passes. The sequence is well defined and assumes the following order. The shell first breaks up the command line into words, using spaces and the delimiters, unless quoted. All consecutive occurrences of a space or tab are replaced here with a single space.

Variable evaluation: Command substitution: Any command surrounded by backquotes is executed by the shell which then replaces the standard output of the command into the command line.

Wild-card interpretation: Any word containing a wild-card is replaced by a sorted list of filenames that match the pattern. The list of these filenames then forms the arguments to the command. PATH evaluation: It finally looks for the PATH variable to determine the sequence of directories it has to search in order to hunt for the command. What difference between cmp and diff commands? It searches for the pattern, specified in the command line with appropriate option, in a file s.

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. Write a command to kill the last background job? Which command is used to delete all files in the current directory and all its sub-directories? What will the following command do? Is it possible to create new a file system in UNIX?

Is it possible to restrict incoming message? What is the use of the command "ls -x chapter[]" 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. If so, what is its use? With the help of this command you can find the disk capacity and free space of the disk.

Is it possible to count number char, line in a file; if so, How? Yes, wc-stands for word count. Name the data structure used to maintain file identification? How many prompts are available in a UNIX system? How does the kernel differentiate device files and ordinary files?

Kernel checks 'type' field in the file's inode structure. How to switch to a super user status to gain privileges? The system asks for password and when valid entry is made the user gains super user admin privileges. What are shell variables? Shell variables are special variables, a name-value pair created and maintained by the shell.

What is redirection? Directing the flow of data to the file or from the file for input or output. How to terminate a process which is running and the specialty on command kill 0? With the help of kill command we can terminate the process.

What is a pipe and give an example? A pipe is two or more commands separated by pipe char ' '.

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That tells the shell to arrange for the output of the preceding command to be passed as input to the following command. When a sequence of commands are combined using pipe, then it is called pipeline.

Explain kill and its possible return values. There are four possible results from this call: This implies that a process exists with the given PID, and the system would allow you to send signals to it. It is system-dependent whether the process could be a zombie.

General UNIX interview questions with answers

On some systems, the process could be a zombie. This means that either the process exists again, it could be a zombie or draconian security enhancements are present e. What is relative path and absolute path. Absolute path: Exact path from root directory. Relative path: Relative to the current path. How are devices represented in UNIX? It provides greater flexibility in mapping the virtual address space into the physical memory of the machine. Allows more number of processes to fit in the main memory simultaneously.

Allows the greater process size than the available physical memory. Demand paging systems handle the memory more flexibly. What is difference between ps -ef and ps -auxwww? This is indeed a good Unix Interview Command Question and I have faced this issue while ago where one culprit process was not visible by execute ps —ef command and we are wondering which process is holding the file.

How do you find how many cpu are in your system and there details? When a program forks and the child finishes before the parent, the kernel still keeps some of its information about the child in case the parent might need it - for example, the parent may need to check the child's exit status. To be able to get this information, the parent calls 'wait ' ; In the interval between the child terminating and the parent calling ' wait ' , the child is said to be a 'zombie' If you do 'ps', the child will have a 'Z' in its status field to indicate this.

The process is dead but have not been removed from the process table. What is "chmod" command? The line you see shows the permission for three different set of people: User is the currently logged in user, while group is for all other member which are part of certain group and others means anyone other than user and group member.

So in above line, user has only read permission, group members has write permissions and other people has only execute permission. If it is a directory then you need execute permission to go inside that directory. See here for more detailed answer. How do you set environment variable which will be accessible form sub shell?

How do you check if a particular process is listening on a particular port on remote host? To read more about telnet read networking command in UNIX. Either by using "uname -a" command or by using "arch" command. How do you find which processes are using a particular file? By using lsof command in UNIX. It wills list down PID of all the process which is using a particular file. How do you find which remote hosts are connecting to your host on a particular port say ? By using netstat command execute netstat -a grep "port" and it will list the entire host which is connected to this host on port What is nohup in UNIX?

An UNIX process started with nohup will not stop even if the user who has stared log off from system. What is ephemeral port in UNIX? Ephemeral ports are port used by Operating system for client sockets.

There is a specific range on which OS can open any port specified by ephemeral port range. If one process is inserting data into your MySQL database?

How will you check how many rows inserted into every second?

Purpose of this Unix Command Interview is asking about watch command in UNIX which is repeatedly execute command provided with specified delay. You have a tab separated file which contains Name, Address and Phone Number, list down all Phone Number without there name and Addresses?

CUT use tab as default separator so you can use. Your application home directory is full? How will you find which directory is taking how much space?

UNIX Interview Questions

By using disk usage DU command in Unix for example du —sh. By using uptime command in UNIX. You have an IP address in your network how will you find hostname and vice versa?

This is a standard UNIX command interview question asked by everybody and I guess everybody knows its answer as well. Please share any interesting UNIX command interview you have come across and I will add into this list. If you are going for any Unix interview on brokerage firm or stock trading company or any Investment bank you can have a quick look here, though most of questions you might already know but its good to review it.

Share to Twitter Share to Facebook. United States. Anonymous said May 16, at 3: May 16, at 7: May 17, at 1: May 17, at 2: May 17, at 3: July 26, at October 6, at 8: Thank you November 22, at January 17, at 2: March 9, at 5: Senthil September 19, at 8: June 28, at July 10, at January 24, at 7: April 4, at 8: August 29, at 2: December 18, at 6: January 29, at April 27, at May 12, at It is good article.

Keep it up. August 19, at 4: September 28, at 3: Newer Post Older Post Home. Subscribe to: Post Comments Atom.The system calls used for low-level process creation are execlp and execvp.

The regions swapped out will be present but only the occupied region slots but not the empty slots that were present before assigning. I have listed down 31 unix interview questions with answers which cover basic unix commands like ls, banner, cat, date, tee, who, man, head, pg, cmp, diff, grep, kill, echo, su etc.

System call results and other information from the OS are presented to the user through an interactive interface. Explain the steps that a shell follows while processing a command.

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