TCS Pre-ILP Unix Assignment


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I know many TCS placed students who are doing their Pre ILP would have searched for this all over Internet. To an extent I feel that it was good that I could not find it online, for a reason that I could get better used to Unix. I strongly recommend each and every one of you reading this to Please try the commands atleast ONCE. Otherwise you are going to be in real trouble at TCS. These basic commands would become part of your life once you Join, and you have to get used to it. There is no excuse for anyone to not know atleast the basic concepts, and in the highly competitive field you will be Pushed down. So take a look at the following for just a hint, or a reference. Myself not sure if the answers are right, thanks a ton to Gibu for helping me out with the solutions. As always, suggestions are welcome. I have created a Group for TCS Pre ILP 2011, please do join, and be a part of Family.
Warning To who ever is going to copy paste and submit the same copy as below, Answers can vary depending on thoughts. There is more than one way for a solution, please do NOT blindly Copy Paste.


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Assignment 1

Question 1:
Write a command to list all the files inside a folder i.e. if there is a folder inside a folder then it should list all files inside the sub-folder which is inside the folder to be listed.
Ans : ls -R

Question 2:
Search all the files which contains a particular string, say “include” within a folder.
Ans: grep include ./*

Question 3:
Rename all the files within a folder with suffix “Unix_” i.e. suppose a folder has two files a.txt and b.pdf than they both should be renamed from a single command to Unix_a.txt and Unix_b.pdf
Ans: for f in *.*; do mv “$f” Unix_”$f”; done

Question 4:
Rename all files within a folder with the first word of their content(remember all the files should be text files. For example if a.txt contains “Unix is an OS” in its first line then a.txt should be renamed to Unix.txt
Ans: for f in *.txt; do d="$(head -1 "$f") ;x=”$(cut -d " " -f1 $f)”  ; mv $f $x; done

Question 5:
Suppose you have a C project in a folder called “project”, it contains .c and .h files, it also contains some other .txt files and .pdf files. Write a Linux command that will count the number of lines of your text files. That means total line count of every file. (remember you have to count the lines in .txt files only)
Ans: wc –l *.txt

Question 6 :
Rename all files which contain the sub-string 'foo', replacing it with 'bar' within a given folder.
Ans:  for i in ./*foo*;do mv -- "$i" "${i//foo/bar}";done

Question 7:
Show the most commonly used commands from “history”. [hint: remember the history command, use cut, and sort it]
Ans: history|sort|cut –d-10 -n

Assignment 2

1.Create a tree structure named ‘training’ in which there are 3 subdirectories – ‘level 1’,’ level2’ and ‘cep’. Each one is again further divided into 3. The ‘level 1’ is divided into ‘sdp’, ‘re’ and ‘se’. From the subdirectory ‘se’ how can one reach the home directory in one step and also how to navigate to the subdirectory ‘sdp’ in one step? Give the commands, which do the above actions?
Ans :  To navigate from ‘se’ to home – cd ~
          To navigate directly to sdp – cd training/level1/sdp

2.How will you copy a directory structure dir1 to dir2 ? (with all the subdirectories)
Ans : cp –R dir1 dir2

3.How can you find out if you have the permission to send a message?
Ans :  ls -l

4.Find the space occupied ( in Bytes) by the /home directory including all its subdirectories.
Ans : du -sb 

5.What is the command for printing the current time in 24-hour format?
Ans : date ‘+%R’

6.What is the command for printing the year, month, and date with a horizontal tab between the fields?
Ans : date ‘+%F’

7.Create the following files: chapa, chapb, chapc, chapd, chape, chapA, chapB, chapC, chapD, chapE, chap01, chap02, chap03, chap04, chap05, chap11, chap12, chap13, chap14, and chap15.
Ans:
Cat > chapa
Contents of file
Ctrl+D

Cat > chapb
Contents of file
Ctrl+D

Cat > chapc
Contents of file
.
.
.
Cat> chap15
Contents of file
Ctrl+D

8.With reference to question 7, What is the command for listing all files ending in small letters?
Ans : find . –name “*[a-z].*”

9.With reference to question 7, What is the command for listing all files ending in capitals?
Ans : find . –name “*[A-Z].*”

10.With reference to question 7, What is the command for listing all files whose last but one character is 0?
Ans: find . –name “*0?.*”

11.With reference to question 7, What is the command for listing all files which end in small letters but not ‘a’ and ‘c’?
Ans : find . –name “*[b d-z].*”

12.In an organisation one wants to know how many programmers are there. The employee data is stored in a file called ‘personnel’ with one record per employee. Every record has field for designation. How can grep be used for this purpose?
Ans : $ grep -c programmer personnel

13.In the organisation mentioned in question 12 how can sed be used to print only the records of all employees who are programmers.
Ans : $ sed -n "/programmer/p" personnel

14.In the organisation mentioned in question 12 how can sed be used to change the designation ‘programmer’ to ‘software professional’ every where in the ‘personnel’ file
Ans : $ sed -e "s/programmer/software professional/g" personnel

15.Find out about the sleep command and start five jobs in the background, each one sleeping for 10 minutes.
Ans: $ sleep 10 & sleep 10 & sleep 10 & sleep 10 & sleep 10 &

16.How do you get the status of all the processes running on the system? i.e. using what option?
Ans : $ ps -e