This assignment continues to practice using the bash shell and basics of combining commands using redirection and pipes.  Electronically turn in a file homework3.txt that contains your answers to several questions below. 

Task 0: Log in to attu First, log in to the shared attu server using a terminal as shown in lecture and in the Working at Home section of the course web site.  Use a terminal and an ssh program, or stand-alone SSH software such as PuTTy on Windows.  Log in to attu using your usual CSE user name and password.  Contact the instructor or CSE support if you cannot log in. There is no ZIP archive of files for this assignment, instead there are files we have placed on attu that you will need to be able to access in order to answer the questions in this assignment. 

Task 1: Learn more about attu  The following are questions about the shared attu Linux system for you to investigate and discover the answers.  Create a text file named homework3.txt and save it somewhere in your home directory, such as in your 390 folder.  In this file, write your answers to the questions below, one per line.  If you like, you can also write the shell command(s) you used to find each answer, though this is not required.  (In Task 2 later, you will need to write the commands used for each item.) The state of attu changes over time; you will receive credit if your answer is plausible for attu in general. 

1. Run the program  ~rea/390/cowsay  with any string of your choice as a command-line parameter, and show the output that is produced.  Paste the output into the top of your homework3.txt file. Note that you can run a program by giving the path to it, you do not necessarily need to change into that directory.  Also note the cowsay  program is not a java program (it is a perl program), you can just run it by typing e.g.: ~rea/390/cowsay  hi 

Answer: 

command: cowsay hi

output: 

 ____
< hi >
 ----
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

2. The attu server is actually "mirrored" as several physical host computers to spread the load of all the students using the server.  Which of these hosts are you logged into now?  (What is its full host name?) 

Answer: ubuntu

3. What is the full path of your home directory on the attu server? 

Answer: /home

4. What version of the Linux kernel does attu use?   (It begins with 3.xxx.) 

Answer: 4.4.0-124-generic

5. (Self-Discovery)  What distribution of Linux does attu use (e.g. Ubuntu, etc.), and what version/release of it?  There isn't a foolproof single command to discover this information, but many Linux systems have a file named /etc/distributionname-release whose text contains the distribution name and number.  So look for a file that is named in this way in the /etc directory.

Answer: Ubuntu 16.04.1 LTS  

6. How much total memory (RAM) does the attu system have, in kilobytes (k)?   (Hint: The program that shows in real time  which of attu's processes areusing the most CPU% also tells about attu's total memory.)

Answer: 

command:cat /proc/meminfo | grep MemTotal
result: 997636KB 

7. What is the process ID number (PID) of the bash process you are currently running for your session on attu?

Answer: 

command: pgrep -f bash
result: 2007 

8. How many total processes are currently running on attu by all users, as reported by the ps command? 

Answer: 

command: ps auxw | wc -l
result: 226

9. What is the total number of files and directories stored directly within the /bin folder on this machine's file system?  (Not including the contents of any subdirectories within /bin .)  (Hint: There are a lot of files; it would take too long to count them all by hand.  Use the wc command to count words or lines in a given input or file.)

Answer: 160 

10. What are the usernames and names of 3 other people logged into attu right now? 

Answer: There is only one user who logged into attu.

11. A small change has been made between the two files below on attu.  What is the difference between the two files?  (Show the literal change between the files, and explain the change in your own words.) ~rea/390/babynames1.txt and  ~rea/390/babynames2.txt 

Answer: babyname2.txt and babyname2.txt don't exist.

Task 2: Bash shell commands on attu For each item below, determine a single bash shell statement that will perform the operation(s) requested.  Each solution must be a one-line shell statement, but you may use input/output redirection operators such as >, <, |, and &&.  Write these commands into your homework3.txt file, one per line.  In your file, write the command that will perform the task described for each numbered item; don't write the actual output that such a command would produce. To test some commands, you should be running on attu.  Use man pages or the Linux Pocket Guide to help you. 

1. Create an alias p for the pico editor.  For example, if the user types p foo.txt, it will run pico foo.txt . 

Answer: alias p='pico'

2. Create an alias ll (two lowercase Ls) that will run ls with appropriate parameters to list all files (including hidden file entries whose names begin with .) in long detailed format. 

Answer: alias ll='ls -al'

3. Create an alias so that when the user types cheat followed by a file name, it will change that file's last-modified date to be June 15 of this year at 1:23pm. 

Answer: alias cheat='touch -t 06151323'

4. Display the differences between the files message 1.txt and message 2.txt (note the spaces in the file names) in directory ~rea/390/, in side-by-side format, ignoring differences in spacing.  (You may want to resize your terminal window wider.) 

Answer: There is a sentence in the message 1.txt file: Cse390a-announce mailing list, but not in the   message 2.txt file.

5. Create a new empty file whose name is the same as whatever user is running the command.  In other words, if user billybob ran this command from directory ~/390/hw2, it would create an empty file named ~/390/hw2/billybob .  (For an extra challenge, can you make it create the file with a .txt extension, such as billybob.txt?)

Answer: touch `whoami`.txt 

6. Display a list of which processes are using the most of attu's CPU or memory; make it update once every two seconds. 

Answer: top -d 2

7. Output the number of processes that the user root is running whose names contain the phrase "sh".  Do not output the names of these processes, only the count of how many there are. (If there are not any such processes at the moment you can try searching for something broader, like all the processes that contain the phrase “sh” to confirm you are doing the question correctly.) 

Answer: 

command:ps -uroot | grep sh | wc -l
result:0

8. (Self-Discovery) The yes command repeatedly outputs the string y ; it is useful only when combined with other commands that expect the user to confirm many actions by typing y or n.  (a) Write a command that runs the Java program Questions.class and automatically answers y to all its questions.  (b) Write a second version that answers n to all the questions.  (Test your command using the file  ~rea/390/Questions.class; you’ll want to copy this file to a directory under your control and run it there, it won’t work if you try to run it from the ~rea/390 directory.  If you do it correctly, the y or n text won't appear on the console.) 

Answer: 

(1)yes | java Questions
  
(2)yes n | java Questions

9. Write a single command that copies the source file Fresh.java from directory ~rea/390/ to the current directory, then compiles the program in the current directory, and if it compiles successfully, runs the program. 

 (This is similar to an exercise on the previous assignment, except we want it to copy and compile as well as run.  But if the copying or compilation produces an error, don't run the program.  Part of the difficulty is in achieving all of this with a single-line command: copying, compiling, and running.  Once your command works for a valid Fresh.java, test it for a bad program by making a copy of Fresh.java and editing it to insert a syntax error.) 

Answer: javac Fresh.java && java Fresh

10. Write a single command that runs the Java program stored in Box.class (assumed to be in the current directory), which reads text from standard input and surrounds it with a text box.  It accepts a command-line parameter of the character to use for the box edges; run the program in such a way that it uses the character X, for this parameter.  Also redirect the program's standard input to come from the file boxinput.txt , and make it write its output to the file box output.txt (note the space in the file name) in the current directory.  If such a file already exists, append the output to the end of this file rather than overwriting. 

 (Hints: Find the files Box.class and boxinput.txt in the ~rea/390/ directory and copy them to your own working directory for testing.  For an extra challenge, try making the tilde character, ~, appear as the box border.) 

Answer: java Box X < boxinput.txt  >"box output.txt"