Question

Task 1: Getting familiar with Unix commands

Questions:

1. How do you remove a directory and all of its contents, including any subdirectories and files, without using rmdir repeatedly?         [5 Points]
2. Go to your home directory (i.e. /home/) and enter the following command: ls -ali
   Explain the output. You need to clearly what each column specifies, what are the values in each column means. Also explain how it is different from: ls -li    [5 Points]
3. How will you copy directory (not an empty directory) from one location to another? [5 Points]
4. Consider a file which consist of:
   
   12
   21
   113
   54
   213
   4
   23
   
   How do you sort the numbers in ascending order? [5 Points]
5. Consider the contents of 3 files as:

file1 Cherries Jackfruit Apples Fig Honeydew Blueberries

file2 Boysenberries Grapes Pineapple Eggfruit Cucumbers

file3 Dates Elderberry Apricots Entawak Cantaloupe Bananas

1. You need to sort all the fruits from the 3 files in descending order and save the content in the file4. All these operations have to be done in a single line.                                           [5 Points]
2. You need to sort all the fruits from the 3 files in descending order, sort them and then save all the occurrences of the word “Apple” along with their index in file4. All these operations have to be done in a single line.                                           [5 Points]

The contents of file4 for case(a) and (b) are as follows:

Pineapple Jackfruit Honeydew Grapes Fig Entawak Elderberry Eggfruit Dates Cucumbers Cherries Cantaloupe Boysenberries Blueberries Bananas Apricots Apples

1:Pineapple 17:Apples

Answer 1

1) rm -r
   Above command will remove all the contents of the directory recursively including all
   of its subdirectories and files.

2)  
   root@tryit-gorgeous:~# ls -ali                                                                                                                       
   total 0                                                                                                                                              
   1838 drwx------ 1 root root 24 Aug 30 07:04 .                                                                                                      
      261 drwxr-xr-x 1 root root 150 Aug 30 07:03 ..                                                                                                     
   19488 drwxr-x--- 1 root root   6 Aug 30 07:03 .config                                                                                                
   19492 drwxr-xr-x 1 root root   0 Aug 30 07:04 hello
                                                                                                  
   root@tryit-gorgeous:~# ls -li                                                                                                                        
   total 0                                                                                                                                              
   19492 drwxr-xr-x 1 root root 0 Aug 30 07:04 hello

   Output meaning of above line :

   19492 : inode number

   d : first character after inode number represents the type of file.
       'd' for directory.

   rwxr-xr-x   :   these nine characters represent permission of current item.
                   first three represent permission for file's owner, next three
                   permission for members of file group, and last three permission for others.
                   r : read permission ; w : write permission ; x : execute permission
                  
   1 : this number represents number of hard links to this item.

   root : this field represent the item's owner. in this case 'root'

   root : this field represnt the group this item belongs, in this case 'root'

   0 : size of item in blocks

   Aug 30 07:04 :   this field represent date and time when item was last modified

   hello : this field represent name of the item, in this case 'hello'

   The only difference in between 'ls-ali' and 'ls-li' is the use of 'a' option in first
   command. Which lists all the items including entries starting with '.' also.
   In this case items with name '.', '..' and '.config' are also listed when first command
   executed.

3)   cp -rp old_directory name new_directory_name
   This command will copy one directory to another location.
   -r command will copy recursively all contents of old directory.
   -p will preserve the old permision and timestamp.
  
4)   sort -n file.txt
   above command will sort the file in ascending order.
   -n is used in case the file consist of numerics.

5)  
   a)   sort -r file1 file2 file3 > file4
       -r option is for sorting in descending order
  
   b)   sort -r file1 file2 file3 | grep -in apple
       this command will give the desired output.
       grep command is for searching strings in files.
       -i : this option ignores the case.
       -n : this option will display line index number.