Lab46 Wiki

Presented within will be various questions evaluating your knowledge and experience gained this semester. In places where you are able, the more you write and explain topics the better the chance you will have of receiving full credit (and alternatively, the more credit you will receive should something be incorrect).

The questions on this experience are open resource with the exception of other individuals. In that respect, it is CLOSED PERSON. This means you are not to communicate with other people (either in the class or otherwise), in real life or electronically. Use your own knowledge, use your skills, and use your ability to access the allowed resources to aid you in coming up with your well thought out answers to each question.

You are allowed, and expected, to ask me questions, so that a problem can be better clarified.

There are three parts to this experience:

• Part I: 8 items, covering all the various concepts we've covered throughout the semester.
• Part II: 4 scripts.
• Part III: 4 items, involving the course and various perspectives you got out of it.

You are to do all questions. Submission is to be in an organized and easy to read format in a plain text file, such as in an e-mail with attachments on Lab46, sent to wedge@lab46.corning-cc.edu and yourself.

You have until 11:59:59pm (that's 23:59:59 in 24-hour time) Friday, December 17th, 2010 to complete and submit this to me.

If desired, our scheduled finals week meeting time is: Monday, December 13th, 2010 from 2:30pm-5:30pm in B003 (our regular room).

Good luck!

For the following permissions:

a. drwxr-x--x
b. crw-r-----
c. -r---w--wx
d. p--xrw-rwx

• Tell me the octal permissions for each.
• Tell me what type of file for each.

Write me regular expressions that, when used against a file like /usr/share/dict/words, will return only the following (give me the entire command-line or regex, AND number of results):

a. All the 6 letter words that begin with "pre" XOR end with "ing".
b. All the words that begin with "pre" or "post" and do NOT end with "ing".
c. All the words whose even placed characters are a vowel (only lowercase, 'y' excluded).
d. All the words whose even placed characters are a vowel (only lowercase, 'y' included).
e. All the words that do not contain any of the letters 'a' or 'A'.
f. Words that do not contain any of your initials (first, middle, last, upper, and lower).

In the /var/public/unix/eoce directory is an executable named mystery. Run this program and tell me the following:

a. Does the program output to STDOUT or STDERR?
b. How can you prove this?

Be sure to justify your answer and provide proof that backs up your claims.

The /etc/shadow file contains account password information for certain users on the system.

a. How would you show me the encrypted password for one of the accounts?
b. If you try it, are you able to accomplish the task? Why or why not?
c. Why do you suppose that is?
d. What would be the benefit of doing something like this?

Be sure to answer ALL four parts.

Tell me whether each of the following is a relative or absolute path:

a. /usr/local/bin/usage
b. bin/bash
c. /usr/share/../../tmp
d. ./var/lib/dpkg

Tell me what type of file (regular, directory, special) for each of the following, and provide your reasoning for such:

a. /etc/group
b. /usr/lib/libsvn_diff-1.so.1.0.0
c. /dev/pts/*
d. /proc/cpuinfo

What tool(s) would I use to access/process the following in the most common sense fashion? Identify what the file is, and show me an example command-line

a. stuff.tar.gz
b. trees.bz2
c. text_file_with_100_lines_you_want_to_read
d. roms.zip

Show me how you'd list the following:

a. All the files in the base of /proc that contain 4 characters and begin with a '1' or a '2'.
b. All the files in the base of /dev that end with '6' or 'v' or 'V'.
c. All the files in the base of /etc that begin and end with an 'r','s','t','l','n', or 'e'.
d. All the files in /bin that are symlinks AND 6 characters in length.

The text-based tetris-bsd on Lab46 enjoys considerable usage. It maintains a scoreboard of all who have played and how high they've placed (and on what level).

I'd like for you to take the tetris scores and write a shell script that will turn it from its multiple page double column output to a unified single-column list.

From that list it creates, identify the user who has the most entries in the high score table, as well as the users who have placed on level 4.

Utilizing the last utility, write a script that will output the following information:

• how many unique IP addresses contacted Lab46 for successful login this month?
• which user had the most bad logins for the month of November?
• which IP address(es) contacted Lab46 the most (you choose- November or December)?
• which IP address(es) contacted Lab46 the least (you choose- November or December)?
• if an argument is given, assume it is a user
  • validate the user (id command), if not a valid user then print appropriate error and exit
  • tally total successful logins for November and December
  • tally total unsuccessful logins for November and December

Write two scripts, each one accepting as input two strings.

Each script must validate whether or not the two input strings are palindromes (or not), and output a message appropriately.

Each script must perform its palindrome processing in an entirely different way from the other.

The intent here is to come up with fundamentally different ways of solving a problem.

Throughout the semester, the Grade Not-Z has been regularly processing your journal entries, attendance, and other assignments into various text files residing in a ~/data/ directory you made earlier in the semester.

Specifically, there are 3 files of interest:

• results.journal - your journal status
• results.unix.assignments - your results on your various labs and case studies
• results.unix.attendance - your attendance/participation metrics

Looking back to the syllabus, you'll see that each of these areas constitutes one of the main sections of the grading policy. The journal is worth 36%, assignment are worth 36%, and attendance/participation is 28%. 36+36+28=100, so the data contained within these files will be used to calculate your grade for the course.

What I'd like you to do is write a script which takes the data in these files, and appropriately calculates and outputs:

• your journal score (out of 36, and percentage complete)
• percentages for below, adequate, and exceeds entries
• achievements unlocked
• largest journal entry (in words), average journal entry (words)
• your assignments score (out of 36, and percentage complete)
• what percentage of your assignments were late, not turned in
• your attendance/participation score (out of 28, and percentage complete)
• your overall score, out of 100, adding these together.

Your script must do the appropriate calculations (is it out of 36 or 28, calculating percentage per each section correctly, etc.) and output the requested information in an easy-to-read fashion.

What is the UNIX philosophy?

And how does that philosophy play a part in various places on a UNIX system, and even in various ideals behind coming up with solutions and computing in general?

The first UNIX filesystems allowed for filenames to be up to 14 characters in length. As time went by, this limit increased to 255 characters, and even larger (around 10,000 characters). In UNIX, there is no concept of an extension (ie in MS-DOS you have 8 characters followed by a 3 letter extention– known as 8.3 notation). However, the concept of the file extension is still in common use but used to help the user distinguish files (just as with the –color=auto option to ls(1), files are colorized). The underlying operating system doesn't care what extension or color the file is, but it can be useful to the user.

In DOS, a common wildcard to specify all files is: *.*

In UNIX, why is * better than: *.*

Explain your answer.

We have spent considerable time and efforts on shell scripting this semester. Especially with our significant example exploring the course offerings, there was an emphasis on the validity of likely many methods for arriving at the solution.

In class explored one example with considerable detail, now I will present you with a few solutions (including what we had done in class) to ask you to pick apart and explain various aspects of the solutions.

Take a look at the scripts and respond to the following:

• What are the differences in the approaches taken by these scripts in tackling the problem?
• What are some advantages to the approach taken in the first script?
• What are some advantages to the approach taken in the second script?
• What are some disadvantage to the approach taken in the first script?
• What are some disadvantage to the approach taken in the second script?
• There are some different RegEx used in both scripts than we saw in class. What are they? What are they doing?

After an exciting and intellectually challenging run, we're arriving at the end of this semester's journey. The course as we all experienced it, unfolds in a manner pertaining in part to how you respond to concepts and topics (do we need more time, can I crank it up a couple notches, etc.) so each semester and each class is entirely different from any other- because of each of you, and all of us, working together and learning together.

So, searching deep down within your soul- balancing reason with emotion, and considering attendance and timeliness; answer me the following:

• What grade do you feel you deserve for this course?
• Why do you feel you deserve this mark? (Justify your answer based on your own perceived performance, not on need.)
• How did you feel about the course?
• Was it useful/interesting to you?
• What was your least favorite aspect, and why?
• What was something meaningful to you with respect to the course? Why does this stick out in your mind?
• Any other comments or suggestions?