Assign 0: UNIX and Bash

Goals for Assignment 0

After the assignment, you should

1. Know how to learn about new commands and use them
2. Know how to make environment variables and customize your environment.
3. Know how to use some chmod, file system, and process commands.
4. Know how to redirect output
5. Have a better understanding of UNIX permissions
6. Understand pipes and how to use them effectively
7. Know how to write basic bash scripts, including using if statements and for loops.

Overview

You're going to practice your Unix commands and set up your environment, and then show that you did them in a bash script that you'll execute and save in an output file.

This is due before class on February 4.

Objective: Environment Variables

1. Create two new environment variables called CS397, which represents the path to the course directory, and HANDOUTS that is the path to the course's handouts directory.
   1. Open ~/.bashrc using emacs or jedit or your favorite text editor

      Recall that hidden files (those that start with .) are not shown by default when you list files in your directory. Use the -a option. In text editors, you may need to figure out how to show hidden files.

   2. At the bottom of the file, create a new variable:
      CS397=/csci/courses/cs397
   3. Export the variable: export CS397
   4. In terminal, run the source command to load your new profile
      source ~/.bashrc
   5. Check that your new variable was created by displaying its value.
   6. Use the variable by going to that directory, i.e., cd $CS397
   7. Follow a similar process for the HANDOUTS variable. Note, since you have the variable CS397, you may want to use that in defining your HANDOUTS variable's value.
2. In a new terminal (so that it loads the updated .bashrc file),
   1. Display the $HANDOUTS variable
   2. Display the basename of $HANDOUTS
   3. Display the directory name of $HANDOUTS

Objective: Learning new Unix commands

Use the man command to learn about the yes and touch command. You'll need to "prove" that you learned these commands later in this assignment.

Objective: Customizing Your Prompt

1. Open up your .bashrc file in your favorite text editor.
2. Search for force_color_prompt
3. Uncomment the line that says fore_color_prompt=yes
4. Search for the definition of PS1.
5. Comment out (#) the PS1 definition. (Which branch of the if should you be in?)
6. Add the following code below the commented out prompt.
   PS1="\e[1;31m\h:\W \u (\!)\$ \e[00m"
7. Source the .bashrc file. What does this prompt look like?
8. Run ps and some other commands to better buess what the prompt is doing.
9. Then try setting it as
   PS1='\e[00;35m\]\! \e[00;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\W\[\033[00m\]\$ '
10. Try out more by checking out the wiki page on customizing your prompt.
11. You can revert your prompt to the original, commented out prompt or to whatever you want to use for your prompt.

Objective: Aliases

1. Open (or create) ~/.bash_aliases file.
2. Create an alias so that ssh aliases to ssh -XY. Then, whenever you ssh, you'll automatically have the -XY options.
3. Reload your configuration file by running source ~/.bashrc Test that your new alias works. (I'll be able to see that you did this correctly from the next objective.)
4. Create an alias called "peptalk" that is aliased to repeatedly print "You can do it!"

Objective: Unix Commands (100 pts)

If you haven't already, create a cs397 directory in your home directory and an assignments subdirectory. Create an assign0 subdirectory within assignments.

In conclusion, you should have the directory $HOME/cs397/assignments/assign0

Do the following steps within ~/cs397/assignments/assign0 directory.

You're going to create a script called assign0.sh in your assign0 directory that demonstrates the following tasks. BUT FIRST, practice them on the command line, then put them into the script, as you go, and make sure the output from the script is what you expect. You will be practicing using both absolute and relative paths in this assignment. Use whichever is easier/simpler (i.e., favor relative paths).

• Show all your aliases in your .bash_aliases file.
• Display the $HANDOUTS variable
• Display the basename of $HANDOUTS
• Display the directory name of $HANDOUTS
• List the contents of /csci/courses/cs397/handouts/assign0 Note that you created environment variables that could be helpful for this task.
• Copy the directory /csci/courses/cs397/handouts/assign0 and all of its contents into this directory. So, you should have a directory that is ~/cs397/assignments/assign0/assign0
• List the contents of the current directory and then your assign0 subdirectory.
• Go into the assign0 directory
• Execute example.sh by executing bash example.sh
• Move lastnames.txt into the parent directory.
• Create a file within your directory, named mine.txt, using the touch command.
• View the contents of your directory.
• View the files' permissions.
• Try running the script as ./example.sh
• Change the permissions of example.sh such that it is executable by you (and only you).
• Now, execute example.sh by executing ./example.sh
• Create a backup copy of firstnames.txt, named with the extension .bkup. (A shortcut would be useful here.)
• Run ps to see the processes running in this terminal.
• Display (only) the first 10 results from ps -ef Note the differences in the displayed output
• Run the above command again and save its output in a file called firstps.out (This should be implemented as a command.)
• Get the last 10 processes and save them in a file called lastps.out
• Display the contents of lastps.out
• Display how much space all the files in the current directory take up, in total. (I want as little output as needed to answer this.)

Creating Your Script

Put the commands above into a script called assign0.sh in the parent assign0 directory. Make sure you have the shebang and high-level comments describing what your script does. Note that some commands that work in the shell may not behave the same way in the script. Check that you're getting the expected results from your commands.

Carefully delete your assign0 subdirectory and all its content.

Then, execute your assign0.sh script (which should create the assign0 subdirectory again) and save its output in a file called assign0.out. (Like all the files you're submitting, this output file should be in your assign0 directory.

A Script to Execute Scripts (30 pts)

Copy the (whole) directory /csci/courses/cs397/handouts/bash/ into your ~/cs397/assignments/assign0 directory.

Write a script called execAll.sh that uses a for loop to get all the files that end in .sh from your bash directory, displays the name of each file, and then executes it.

Save the output from your script in a file called execAll.out

Script to Submit Your Assignment (30)

You need to submit everything from the assignment directory into your turnin directory.

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 (/csci/courses/cs397/turnin/yourusername), still named assignmentname. For example, for this assignment, the directory is assign0. In the end, all of your submitted assignment files in /csci/courses/cs397/turnin/yourusername/assign0
• The script should use your environment variable $CS397
• If you previously submitted the assignment into the turnin directory, the script should move the existing submission into a backup copy in your turnin directory, with the date and time in its name to keep track of versions of the submission. Then, copy the current version of the assignment into the turnin directory.
• Upon submission (read: copy), show the contents of the directory that is now in the turnin directory to show that the submission script worked. It is helpful to have some output before this that states what is happening. (Yes, yes, I know that's not following the Unix philosophy.)
• The script should handle errors and display appropriate and descriptive/helpful messages to the user, including:
  • incorrect number of arguments
  • the assignment directory to copy doesn't exist

Clean up (read: carefully remove) any extra copies of directories in your turnin directory that you created during testing.

Demonstrate that your script worked by running: bash submit397.sh assign0 > assign0_sub.out

Finishing up: What to turn in for this assignment

Run your submit397.sh script one more time--without the output redirection--so that your assign0_sub.out file will be in your final submission in your turnin directory. (There should be a backup copy of the directory from when you ran the script above.)

Grading (160 pts)

• See breakdown above.