UniX Exercise 1

1. Write a command to print the ouput “Today is Tuesday, 5^th day of month, year”.

Sol.            date +”Today is %a, %d of %b, %Y”

2. Assume that files in a directory are “filename_dd_mm_yy”, write a command to list the files created today.

Sol.            ls *_`date +”%d_%m_%y”`

3. Write a command to copy a file x to y using cat.

Sol.            cat x > y

4. Write a command to copy the contents of 2 files into a third file.

Sol.            cat x y > z

5. Write a command to copy the contents of x, user input, y into a file.

Sol.            cat x - y > z

6. Write a command to copy the contents of x and y prefixing the file name before starting file contents.

Sol.            ls x > z; cat x >> z; ls y >> z; cat y >> z

                                          (Or)

                  (ls x; cat x; ls y; cat  y) > z

7. Write a command to generate the following into a file

Files of the directory on

           

Total files in the directory are

Sol.            (echo –e “Files of the directory `pwd` on `date +%D`\n\n”;

 ls -l;echo –e “\n\n Total files in the directory are `ls –l | wc –l`”) > z

8. Assume package name of each java program is in line 1, write a command to display all package names.

Sol.            head -1 *.java

9. Write a command to display top 3 files which were created recently.

Sol.            ls -ltr | head -4 | tail -3

                                          (Or)

ls -ltr | tail +2 | head -3

10. Write a command to display lines 23 to 44 of file y.

Sol.            head -44 y | tail +23

11. Write a command to count number of words in last but one line of file y.

Sol.            tail -2 y | head -1 | wc -w

12. Write a command to display 15^th line of every file in the current dir.

Sol.            cannot be solved with commands need to write shell script.

13. Write a command to display the total number of bytes used by all files of the current directory.

Sol.            wc –c * | tail -1

                              (or)

                 

                  cat * | wc -c

     

14. Write a command to copy file x to y only if y not exits.

Sol             ls y || cp x y

15. Write a command to convert all characters of file x to capitals.

Sol             cat x | tr “a-z” “A-Z”

                              (or)

                 

                  tr “a-z” “A-Z” < x

16. Write a command to count number of spaces in line 15 of file x.

Sol             head -15 x | tail -1 | tr –cd “ “ | wc -c

17. Write a command to convert all tabs to spaces of a file.

Sol             cat x | tr “\t” “ “

18. Write a command to join all lines of a file.

Sol             cat x | tr “\n” “ “

19. Write a command to join lines 15 & 24 of a file.

Sol             (head -15 x | tail -1; head -24 x | tail -1) | tr “\n” “ “

(or)

                  echo ‘head -15 x | tail -1` `head -24 x | tail -1`

20. Write a command to display machine hardware type.

Sol             uname –a | cut –d” “ –f6

21. Write a command to display file permissions and filename.

Sol             ls -l | tr -s " " | cut -d" " -f1,9

22. Write a command to display the file mask applied for file owner.

Sol             umask | cut –c 1

23. Write a command to display empno, empname and sal from emp.db.

Sol             cut -d"|" -f1-2,6 emp.db

24. Write a command to display the total time taken for the above query.

Sol             time cut -d"|" -f1-2,6 emp.db | tail -3 | head -1

25. Write a command to calculate total amount used by company as salaries.

Sol             echo `cut -d"|" -f6 emp.db | tail +3 | tr "\n" "+"` 0 | bc

26. Write a command to calculate total amount used by company as salaries along with the message “Total Salary of all employees is : ”.

Sol             echo -e "Total salary of all employess is  : \c";

echo `cut -d"|" -f6 emp.db | tail +3 | tr "\n" "+"` 0 | bc

27. Write a command to count number of employees in department 10.

Sol             cut -d"|" -f8 emp.db | grep -wc 10

28. Write a command to list all employees in the department in which SMITH is working.

Sol             cut -d"|" -f2,8 emp.db  | \grep -w `cut -d"|" -f2,8 emp.db  |

grep -w SMITH | cut -d"|" -f2