TCS Unix Assignment 2: Basics of Unix

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?

Answer:

1.To go home directory from se  =   cd ~

Here: cd = change directory, ~  = for home directory.

2.To navigate to subdirectory sdp  = cd training/level1/sdp

 

2. How will you copy a directory structure dir1 to dir2 ? (with all the subdirectories)

Answer: cp –R dir1 dir2

Here: cp = copy,    -R  =copy directories recursively.

 

3. How can you find out if you have the permission to send a message?

Answer:  ls -l

4. Find the space occupied ( in Bytes) by the /home directory including all its subdirectories.

Answer:  du -sb

Here: du  =  outputs the number of kb used by each subdirectory.

-s   =including subdirectory (total)  , -b  = bytes

 

5. What is the command for printing the current time in 24-hour format?

Answer:   date  +%R

Here : %R  = 24 hr format (hr:min)

 

6. What is the command for printing the year, month, and date with a horizontal tab between the fields?

Answer:   date  +%F

Here : %F  = Full date ;%Y-%M-%D

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.

Answer:

Cat > chapa Contents of file Ctrl+D           Cat > chapb Contents of file Ctrl+D

Cat > chapc Contents of file Ctrl+D           Cat > chapd Contents of file Ctrl+D

Cat > chape Contents of file Ctrl+D           Cat > chapA Contents of file Ctrl+D

Cat > chapB Contents of file Ctrl+D           Cat > chapC Contents of file Ctrl+D

Cat > chapD Contents of file Ctrl+D           Cat > chapE Contents of file Ctrl+D

Cat > chap01 Contents of file Ctrl+D           Cat > chap02 Contents of file Ctrl+D

Cat > chap03 Contents of file Ctrl+D           Cat > chap04 Contents of file Ctrl+D

Cat > chap05 Contents of file Ctrl+D           Cat > chap11 Contents of file Ctrl+D

Cat > chap12 Contents of file Ctrl+D           Cat > chap13 Contents of file Ctrl+D

Cat > chap14 Contents of file Ctrl+D           Cat > chap15 Contents of file Ctrl+D

 

Here: cat  =    to concatenate a file.

>    =    to redirect the output

8. With reference to question 7, What is the command for listing all files ending in small letters?

Answer:   find  . –name “*[a-z].*”

9. With reference to question 7, What is the command for listing all files ending in capitals?

Answer:   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?

Answer:   find . –name “*0?.*”

Here: ? = wildcard(will match exactly one character.)

11. With reference to question 7, What is the command for listing all files which end in small letters but not ‘a’ and ‘c’?

Answer:    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?

Answer:   $ grep -c programmer personnel

Here: -c = count

13. In the organisation mentioned in question 12 how can sed be used to print only the records of all employees who are programmers.

Answer:   $ sed -n “/programmer/p” personnel

Here: sed =stream editor

/ /p   =for printing pattern space

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

Answer:   $ sed -e “s/programmer/software professional/” personnel

Here: sed =stream editor

-e  = script

s/regexp/replacement     =for replacement

 

 

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

Answer:   $ 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?

Answer:   $ ps –e

Here:ps= displays information about the selection of active processes.

-e  = select all processes.