Unix questions asked in aptitude and inteviews for MCA,BCA,ME,BE,M.Tech AND B.Tech

Unix Aptitude Questions


1.Display the first line of a file is using the "head" command.
$> head -1 file.txt


2.Display the first 2 records of the file using the "head" command.
$> head -2 file.txt


3.Another way can be by using "sed" command.
Sed is a very powerful text editor which can be used for various text manipulation purposes like this.
$> sed '2,$ d' file.txt
The 'd' parameter basically tells "sed" to delete all the records from display from line 2 to last line
of the file (last line is represented by $ symbol). It does not actually delete those lines from the file,
it just does not display those lines in standard output screen. So you only see the remaining line which is the 1st line.


4.Display the last line of a file using "tail" command.
$> tail -1 file.txt


5.Display the last line of a file using "sed" command.
$> sed -n '$ p' test
'$' stands for the last line of the file. So '$ p' basically prints (p for print) the last line in standard output screen. '-n' switch takes sed to silent mode so that sed does not print anything else in the output.


6.Display n-th line of a file.
$> sed –n ' p' file.txt
   indicates actual line number whose content is to be displayed. So if you want to print the 8th line, the command will be
$> sed –n '8 p' test


7.Display n-th line of a file using "head"and "tail" command.
$> head -  file.txt | tail -1
You need to replace with the actual line number. So if you want to print the 8th line, the command will be
$> head -8 file.txt | tail -1


8.Remove the first line or header from a file?
$> sed '1 d' file.txt
It just prints out all the lines except the first line of the file on the standard output. It does not really change the file in-place.


9.Delete the first line from the file itself.
there are two ways to do it :-
i)Either you can redirect the output of the file to some other file and then rename it back to original file.
$> sed '1 d' file.txt > new_file.txt
$> mv  new_file.txt  file.txt

ii) Use an inbuilt  "sed switch '–i' which changes the file in-place.
$> sed –i '1 d' file.txt


10.Remove the last line or trailer from a file in Unix script?
$> sed –i '$ d' file.txt


11.How to remove certain lines from a file in Unix?
To remove content  from line    to line  from a given file :-
$> sed –i '5,7 d' file.txt
The above command will delete line 5 to line 7 from the file file.txt

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10th 3i InfoTech Academic Books Accenture ACIO ActiveX ADT Agricultural AIEEE Air Force Algebraic Amdocs Android Answers Application Development Aptitude Aptitude Questions Architectures ASP ATOS B.Sc B.Tech.B.E. Bank Exam BCA BE Board Exam Books break-continue Business Plan C C Programming C# C++ Campus campus interview Candidate profile Capgemini Career CDS Certification CET Challenge Circle Cisco class code Cognizant communication Company Company Profile Competitive Exams computer Computer Networks concentric circles constructor Course Credit Suisse CSS CTS Data Structure DBMS DC Deloitte difficult interview questions dimensions Distributed Computing do while dotNet Download ds Dynamic Web Development e-Admit card Educational engineering entertainment Even Odd Events exam schedule exception for loop fresher GATE general Discussion general knowledge Get Placed Government Job Hall Ticket HCL how to answer How to Prepare HR HR Interview HSC hypertext preprocessor IB IBM IBPS IIT Indian Army Information infosys Intelligence Bureau Internship interview Experience interview questions Interview Tips IntroC IntroC# IntroJava IntroPHP IT J2EE J2ME Java JavaScript jobs Language Books Language Tutorial Languages limit number of objectsJava Limit the number of objects being created in JAVA Linux Linux Administrator Linux Developer Logical Questions loops M Tech M.E. M.Tech M.Tech AND B.Tech Management Management Skills Matrices MBA mca ME microsoft mistakes Mixture Mobile Computing mock questions mock test MySql naukri NDA OOP opening Operating System Oracle paper Persistent PHP php programming php string variables PL/SQL Placement placement guide Placement Paper Placement Process preparing for placement presentation probability Problems Professional program Programming Project Engineer project idea Projects Puzzle qualities Question of the day Questions Quiz Question Recruitment Recruitment Pattern Requirement Result Resume Reviews Screen Sizes Scripting Session Skills Software Software Engineering solved papers Source Code Speed time and distance SQL SSC story Stress Interview Study Material study tips submit resume Synonym TCS Tech Mahindra tech news Technical Books Technical Interview Testing thank you letter Thought Time Table TutC++ Unix questions asked in aptitude and inteviews for MCA UPSC verbal Web Designing Web Developer Website Development What to read while loop Wipro Writing Resume