SOLVED CSCI 4100 Assignment 3 Writing a bash Shell Script

Learning Outcomes Write a bash shell script. Required Reading Linux - Chapters 8 and 10 Instructions For this assignment you must write a bash shell script that keeps track of a list of email contacts by storing them in a text file called contacts.dat. The source file should be called yourlastnameAssign3.sh, except with your actual last name Your program should present a menu to the user with the following options: 1. Add a contact 2. Remove a contact 3. Find a contact 4. List all contacts 5. Exit the program The first option should prompt for a full name and check to see if there is already an entry containing this name in contacts.dat. If there is already an entry for this name it should display a message indicating that an entry already exists. If not, it should prompt for the email address, then add a line contacts.dat containing the name followed by a comma, followed by the email address. The second option should prompt for a full name, then remove the any lines from contacts.dat containing this name. The third option should prompt for a full name, then display any lines from contacts.dat containing this name. The fourth option should display the contents of contacts.dat sorted by last name. The fifth option should exit the script If the user chooses any of the first four options, once the action has been performed the menu should be displayed again and the user should be prompted to make another choice. 1 Helpful Commands and Options Your shell script will need the file called contacts.dat to exist in order to work. If you execute the following command at the beginning of your script: touch contacts.dat This will create an empty text file the first time the script runs, and verify that it exists when you run the script again. The read command prompts for input and stores it in a variable. You can use the -p option to provide the user with a prompt: read -p "Enter your name: " name This will store whatever the user enters in the variable name. The grep command will display the lines in a file that match a given pattern. You can suppress the output using the -q option if all you want is to determine if such a line exists: if grep -q pattern file then # do stuff else # do other stuff fi You can display all of the lines that do not match a pattern using the -v option: grep -v pattern oldfile > newfile This is one way to remove lines matching a pattern from a file. The sort command sorts a file alphanumerically by line. If you want to sort by a specific field of a file containing a sequence of records, you can use the -k option: sort -k 1 file # sorts by first field sort -k 2 file # sorts by second field Testing and Debugging Shell Scripts The easiest way to debug a shell script is to test each command individually using the shell. If you want to know the exit status of a command, you can display the special variable $?, which evaluates to the exit status of the most recently executed command: $ ls nosuchfile.txt ls: nosuchfile.txt: No such file or directory $ echo $? 1 If more substantial debugging is required you can run bash directly using the -x option: $ bash -x hello.sh + echo 'Hello World!' Hello World! All executed commands will appear in a line with a + at the beginning before they are executed. 2 Sample Run Your output should look similar to the following: Select one of the following options: ------------------------------------ 1. Add a contact 2. Remove a contact 3. Find a contact 4. List all contacts 5. Exit the program Enter a choice (1-5): 1 Enter a name: Nicholas Coleman Enter an email address: colemann@apsu.edu Select one of the following options: ------------------------------------ 1. Add a contact 2. Remove a contact 3. Find a contact 4. List all contacts 5. Exit the program Enter a choice (1-5): 1 Enter a name: John Nicholson Enter an email address: nicholsonj@apsu.edu Select one of the following options: ------------------------------------ 1. Add a contact 2. Remove a contact 3. Find a contact 4. List all contacts 5. Exit the program Enter a choice (1-5): 4 Nicholas Coleman, colemann@apsu.edu John Nicholson, nicholsonj@apsu.edu Select one of the following options: ------------------------------------ 1. Add a contact 2. Remove a contact 3. Find a contact 4. List all contacts 5. Exit the program Enter a choice (1-5): 1 Enter a name: Nicholas Coleman There is already an entry for Nicholas Coleman 3 Select one of the following options: ------------------------------------ 1. Add a contact 2. Remove a contact 3. Find a contact 4. List all contacts 5. Exit the program Enter a choice (1-5): 3 Enter a name: Nicholas Coleman Nicholas Coleman, colemann@apsu.edu Select one of the following options: ------------------------------------ 1. Add a contact 2. Remove a contact 3. Find a contact 4. List all contacts 5. Exit the program Enter a choice (1-5): 2 Enter a name: Nicholas Coleman Select one of the following options: ------------------------------------ 1. Add a contact 2. Remove a contact 3. Find a contact 4. List all contacts 5. Exit the program Enter a choice (1-5): 4 John Nicholson, nicholsonj@apsu.edu Select one of the following options: ------------------------------------ 1. Add a contact 2. Remove a contact 3. Find a contact 4. List all contacts 5. Exit the program Enter a choice (1-5): 5 Thanks for using this program! What to Hand In Download the source file yourlastnameAssign3.sh to your local machine, then upload it to D2L in the dropbox called Assignment 3. 4