Write a shell script (called phone) that creates a simple telephone list (create an empty file called phone list in your home directory: /home/user-name/phone list). Each line in this file consists of two fields: a name and a phone number. The script shall do the following: 1. When the user types the command: phone -a name number, this will add a new record (name, number) to the list. If the name or the number or both are missing, nothing happens. 2. When the user types the command: phone -g name then the script should search in the file /home/user-name/phone list and get and display all (name, number) entries matching the specified name. 3. When the user types the command: phone -c number1 number2 then the script should change the existing match of number1 in the file /home/user-name/phone list to number2. 4. When the user types the command: phone -d name number then the script should delete from the file /home/user-name/phone list all existing records that match (name, number). 5. When the user types the command: phone -d name then the script should delete from the file /home/user-name/phonelist all existing records that have a matching name. 6. When the user types the command: phone -d number then the script should delete from the file /home/user-name/phonelist all existing records that have a matching number. 7. When the user types the command: phone alone, or with no switch then the script should display a list of all the (name, number) entries it finds in /home/user-name/phonelist file.