1. What is UNIX?
It is a portable operating system that is designed for both efficient multi-tasking and multi-user functions. Its portability allows it to run on different hardware platforms. It was written in C and lets the user do processing and control under a shell.
2. What is Wild-Card Interpretation?
A command line includes wild-card characters such as ‘*’ or ‘?’. They are substituted by the shell with an organised list of files whose pattern matches the input command. Wild-card fonts set up a list of files for processing instead of having it stipulated one at a time.
3. What are the main features of UNIX?
- Machine independent
- Multi-user operations
- Unix Shells
- Hierarchical file system
- Pipes and filters
- Background processors
- Development tools.
4. Describe links and symbolic links in UNIX?
The second name for a file called a Link. It is used to assign more than one name for a file. It is not valid to assign more than one name to a directory or to link filenames on different computers.
General command ‘– ln filename1 filename2’
A symbolic link is the files that use to contain only the name of other files include in it. Directed to the files pointed by it is the operation of the symbolic link.
General command ‘– ln -s filename1 filename2’.
5. What is the best way of viewing this course?
You have to just watch the course from beginning to end. Once you go through all the videos, try to answer the questions in your own words. Also mark the questions that you could not answer by yourself. Then, in second pass go through only the difficult questions. After going through this course 2-3 times, you will be well prepared to face a technical interview in Unix topic.
6. What is a Kernel?
The kernel is the UNIX operating system master program that controls the computer’s resources assigning them to different users and carrying out different tasks. However, the Kernel doesn’t have direct dealing with a user. It begins a separate interactive program called a shell for each user when they log on.
7. 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.
8. How are devices represented in UNIX?
All devices are represented by files called special files that are located in/dev directory. Thus, device files and other files are named and accessed in the same way. A ‘regular file’ is just an ordinary data file in the disk. (Oracle Unix Interview Questions)
9. How will you run a process in background? How will you bring that into foreground and how will you kill that process?
For running a process in background use “&” in command line. For bringing it back in foreground use command “fg jobid” and for getting job id you use command jobs, for killing that process find PID and use kill -9 PID command. This is indeed a good Unix Command interview questions because many of programmer not familiar with background process in UNIX.
10. 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. By using nslookup command in UNIX, you can read more about convert IP Address to hostname in Unix here.
I hope this UNIX command interview questions and answers would be useful for quick glance before going for any UNIX or Java job interview. 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.
11. What is the description for Kernel?
Kernel is the master program with UNIX operating system that controls the resources of the computer. The resources allocation to different users and tasks handle by this section. Kernel do not have direct communication with the user and it starts separate interactive program call shell to each user when login to the system.
12. What is mean by Super User?
The user with access to all files and commands within the system is called super user. Generally, super user login is to root and the login is secured with the root password.
13. What is process group?
A collection of one or more processes is called process group. There is a unique process id for each process group. The function “getpgrp” returns the process group ID for the calling process.
14. Describe fork() system call?
The command use to create a new process from an existing process is called fork().The main process is called parent process and new process id called child process. The parent gets the child process id returned and the child gets 0. The returned values are used to check which process which code executed.
The returned values are used to check which process which code executed.
15. What are the Filters?
A Filter refers to a program that can get input from typical input, perform an operation on the output and write results to standard output. A Filter is also any program that can be used between two other programs in a pipeline.
16. What is nohup in UNIX?
Nohup is a special command which is used to run process in background, but it is slightly different than & which is normally used for putting a process in background. An UNIX process started with nohup will not stop even if the user who has stared log off from system. While background process started with & will stop as soon as user logoff.
What type of buffer is supported by Unix.
Un-Buffered. (Oracle Unix Interview Questions)
17. How do you check if a particular process is listening on a particular port on remote host?
By using telnet command for example “telnet hostname port”, if it able to successfully connect then some process is listening on that port. To read more about telnet read networking command in UNIX.
18. What is difference between HardLink and SoftLink in UNIX?
I have discussed this Unix Command Interview questions in my blog post difference between Soft link and Hard link in Unix.
19.How do you find which process is taking how much CPU?
By using “top” command in UNIX, there could be multiple follow-up UNIX command interview questions based upon response of this because “TOP” command has various interactive options to sort result based upon various parameter.
20. What is Zombie process in UNIX? How do you find Zombie process in UNIX?
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.)
Zombie : The process is dead but have not been removed from the process table.
21. 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.
22. What are Key Features of the Korn Shell?
The features are:
• Job control
• Command Aliasing.
• String manipulation capabilities.
• Built-in Integer Arithmetic.
• History mechanism with a built-in editor that copies emacs or VI.
23. What are the topics covered in this course?
We cover a wide range of topics in this course. We have questions on Unix commands, concepts etc. (Oracle Unix Interview Questions)
24. What is a single user system?
A personal computer with an operating system which was designed to operate by a single user at a given time. Single user system becomes more popular since low-cost hardware and availability of wide range of software to perform difference tasks.
25. Explain the following sentence?
It is not advisable to use root as the default login.
Ans) The root account is very important and it can leads to system damage easily with abusive usage. So that the securities that normally apply to user accounts are not applicable to the root account.
26. What is the FIFO?
FIFO (First In First Out) is also called named pipes and it is a special file for date transient. Data is read only in the written order. This is use to inter-process communications, where data write to one end and reads from another end of the pipe.
27. What is the utilization of interfaces?
An interface takes after a class in which none of the strategies have been executed—the system marks are there, yet the body of each methodology is void. To use an interface, another class must realize it by giving a body to most of the procedures contained in the interface. Interfaces can give a layer of reflection to your code. They isolate specific execution of a system from the declaration for that procedure. In this manner, you can have unmistakable use of a methodology in perspective of your particular application.
28. What are the responsibilities of a shell?
- Program Execution
- Input/output redirection
- Filename and variable substitution
- Pipeline hookup
- Environment control
- Integrated programming language.
29. What is the UNIX command to list files/folders in alphabetical order?
The ‘ls –l’ command is used to list down files and folders in alphabetical order. When you use ‘ls –lt’ is list down files /folders sorted with modified time. (Oracle Unix Interview Questions)
30. What are the different file types available with UNIX?
Character special files
Block special files
31. Describe the term directory in UNIX?
A specialized form of a file that maintains a list of all the files which include in it is called a directory. Each file assigns to a directory.
32. What is called Shell?
The interface between user and system called a shell. Shell accepts commands and set them to execute for user operations.
33. What is the level of questions in this course?
This course contains questions that are good for a Fresher to an Architect level. The difficulty level of question varies in the course from a Fresher to an Experienced professional.
34. How do I separate development from production environment?
Depending on requirements for the availability of the application, the size of the user population and other factors you can decide how to divide the development environment from the production environment.
For certain applications, it is acceptable to combine the development server with the deployment server, as long as the end users understand that sometimes the application is not available.
Other applications may require two (development and production) or even three (development, test and production) servers.
In Application Express applications can be moved from environment to environment using an export and import facility for application definitions.
With one server available to run the database and Application Express, you can still separate the development version of an application from its production version by using two workspaces accessing separate schemas.
In this case one workspace will be used by developers and the other will be the workspace in which the application is deployed in production.
35. What is Inode?
An inode is an entry on a section of the disk set which is set aside for a file system. The inode holds nearly all the information about a file. It includes:
• The place on the disk where the file starts.
• Who owns the file.
• The size of the file.
• When the file was last used.
• When the file was last changed.
• What the various read, write and execute permissions are.
An Online Course in UNIX Fundamentals.
Online IT Courses offers a course in UNIX fundamentals. You will get technical knowledge on how to organise, install and manage UNIX. You will learn to:
• Organise UNIX
• Configure and manage devices.
• Make use of the command line.
• Add groups and users.
• Set up a firewall.
A Prerequisite – having technical knowledge of operating systems is a bonus.
Target Audience – System Administrator.
Limitless access to their IT professionals’ community.
Available consultants to advise you about the study and career options.
Certified teachers with profound knowledge.
Access to the platform.
When you feel confident enough to start a career in the field put together your resume and prepare for the interview by studying the UNIX interview questions. You are also able to get qualifications. UNIX is quite logical, so knowledge of basic commands and a little imagination will get you through the interview. Hopefully, this will lead to a rewarding career.
36. Is it Possible to See Information About a Process While it is Being Executed?
Every process is uniquely recognised by a process identifier. It is possible to view details and status concerning a process by using the ‘ps’ command. (Oracle Unix Interview Questions)
37. What are the different type of variables used in a Shell Script?
In a shell script we can use two types of variables :
System-defined variables are defined or created by Operating System(Linux) itself. These variables are generally defined in Capital Letters and can be viewed by “set” command.
38. What is session?
A Session is a collection of one or more process group. A process establish a new session by calling setsid function. This function return process groupid ok.
39. 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.
40. What is ‘ps’ command for?
The ps command prints the process status for some or all of the running processes. The information given are the process identification number (PID),the amount of time that the process has taken to execute so far etc.
41. What is RAW datatype?
RAW data type is used in storing values in binary data format. The maximum size of a RAW in a table is 32767 bytes. (Oracle Unix Interview Questions)
42. You have a tab separated file which contains Name, Address and Phone Number, list down all Phone Number without there name and Addresses?
To answer this Unix Command Interview question you can either you AWK or CUT command here. CUT use tab as default separator so you can use
cut -f3 filename.
43. What is “chmod” command?
chmod command is used to change permission of a file or directory in UNIX. The line you see shows the permission for three different set of people : user, group and others. 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. Each group has three permissions rwx stands for read, write and execute and they are written as user_group_others. 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.
44. How do you check how much space left in current drive?
By using “df” command in UNIX. For example “df -h .” will list how full your current drive is. 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.
45. What is the kernel in UNIX?
Kernel is the name of Operating System in UNIX. It is the kernel Job to keep each process anduser separate and to regulate to access the system hardware
46. Write command to list all the links from a directory?
In this UNIX command interview questions interviewer is generally checking whether user knows basic use of “ls” “grep” and regular expression etc. You can write command like: ls -lrt | grep “^l”
47. What is the fastest query method to fetch data from the table?
You can use ROWID to fetch Row from the table. The use of ROW ID is the fastest query method for fetching data from the table.
48. How do you see command line history in UNIX?
Very useful indeed, use history command along with grep command in UNIX to find any relevant command you have already executed. Purpose of this Unix Command Interview Questions is probably to check how familiar candidate is from available tools in UNIX operation system.
49. What is difference between ps -ef and ps -auxwww?
UNIX interview questions answers, UNIX Linux questionsThis 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.
ps -ef will omit process with very long command line while ps -auxwww will list those process as well.
50. How will this course help me?
By attending this course, you do not have to spend time searching the Internet for Unix interview questions. We have already compiled the list of the most popular and the latest Unix Interview questions.