Assign 3: Bash Scripts

Due: Monday before class

Goals for Assignment 3

After the assignment, you should know how to write basic bash scripts, including using if statements and for loops.

Objective: Writing Bash Scripts (100 pts)

Create an assign3 subdirectory within your cs397/assignments directory.

Converting Assignment 2 (10 pts)

Copy your regex.txt file from the last assignment into this directory and name it regex.sh. Convert the contents of the file into a shell script.

As with all scripting assignments, comment your code as appropriate. At the very least, your name and a high-level description of the script should be at the top of the file.

Using the script command, demonstrate your shell script in a file called regex.out

Executing Scripts (20 pts)

Copy the (whole) directory /csdept/courses/cs397/handouts/bash/ into your assign3 directory.

Write a script called execAll.sh that uses a for loop to get the files from the bash directory and then executes each script.

Demonstrate your script in a file called execAll.out

Have I Got a Case for You! (20 pts)

bash scripts tend to be practical. This is not practical.

Create a script called legs.sh that prompts the user for the name of an animal and tells the user how many legs an animal has.

• If it's a spider or an octopus, it has 8 legs (okay, tentacles, but whatever)
• If it's a horse or a dog, it has 4 legs.
• If it's a kangaroo or a person, it has two legs
• If it's any kind of cat or any kind of cow, it has four legs.
• Otherwise, the animal has an unknown number of legs.

Write the script using as little code as possible.

Demonstrate your Bash script in a script named legs.out.

Example Output

$ bash legs.sh
Enter an animal: kangaroo
The kangaroo has two legs

$ bash legs.sh
Enter an animal: spider
The spider has eight legs

$ bash legs.sh
Enter an animal: octopus
The octopus has eight legs

$ bash legs.sh
Enter an animal: dog
The dog has four legs

$ bash legs.sh
Enter an animal: ostrich
The ostrich has an unknown number of legs

$ bash legs.sh
Enter an animal: cat
The cat has four legs

$ bash legs.sh
Enter an animal: alley cat
The alley cat has four legs

$ bash legs.sh
Enter an animal: tom cat
The tom cat has four legs

$ bash legs.sh
Enter an animal: Jersey cow
The Jersey cow has four legs

Script to Submit Your Assignment (50)

You need to remember the command to submit your assignment every time. So, let's automate it!

Use your development skills to build the script in pieces to make sure it's working correctly.

Script Requirements:

• The script should be called submit397.sh
• The script should take a command-line argument that is the name of the assignment.
• The script should copy your assignment directory (likely located in ~/cs397/assignments/assignmentname) to your turnin directory.
• The script should use your environment variable $CS397
• If you previously submitted the assignment into the turnin directory, the script should copy the old assignment into a backup copy in the turnin directory, with the time in its name to keep track of versions of the submission. Then, copy the current version of the assignment into the turnin directory.
• The submission (directory and contents)'s group should be cs397, and the permissions should be set such that the group has read and execute permissions (but not write) but others have no permissions on the directory. Note that this does not mean that others can access your assignment because the $CS397/turnin/username directory's group is turnin; I am the only member of that group.
• Upon submission (read: copy), show the contents of the turnin directory to show that the submission worked.
• The script should handle errors and display appropriate messages to the user, including:
  • incorrect number of arguments
  • the assignment directory to copy doesn't exist

Clean up (read: remove) all your extra copies of submitted assignments that you created during testing.

Using the script command, demonstrate your shell script in a file called submit.out

Finishing up: What to turn in for this assignment

Use your submit397.sh script to turnin your assignment into the turnin directory.

Grading (100 pts)

• 100 pts: Correct scripts, well-documented, demonstrated.