Project: WEEK 4 UNIX REVIEW

To practice/review some previously learned skills in order to obtain better mastery.

Since we have our President's Day mini break next week, we will not actually have the sit-down portion of the class.

Instead of giving you some amazing new mind-blowing project to redefine your very life as we know it, I figured I'd instead give you a chance to take a quick breather and get in some review prior to resuming in full force.

For this week, the main topic of review will be file permissions. We see them when running an ls -l, for example:

lab46:/usr/local/bin$ ls -l submit tclbiff
-rwxr-xr-x  1 root   staff    115 Oct 14  2010 sshfix
-rwxr-x---  1 wedge  lab46   4651 Jan 27 05:58 submit
lab46:/usr/local/bin$ 

Of course, the file permission part is:

    -rwxr-xr-x

We split this into 3 fields (the leftmost field is for file type) into user, group, and other.

Breakdown is as follows:

• read (r) is 4
• write (w) is 2
• execute/search (x) is 1
• nothing (-) is 0

In any given field, we add up the values, which will result in a value within the range 0-7.

So, in our example above, broken down showing the component permissions:

               u      g      o
          -   rwx    r-x    r-x
               7      5      5

I wrote a tool for you to use in this project called urev.

Your task will be to run this and complete 96 problems, in groups of 12 at a time (so you don't blow through them all in one sitting.. there's also a time delay before you can do the next set of 12– so you clearly shouldn't wait until the last minute).

To use urev, basically type in the 3 octal values matching the problem displayed (in the above example, you'd type in '7' '5' and '5', and upon pressing each one, it will appear on the screen.

If you get all 3 correct, you'll earn a point. (Careful not to type too fast, otherwise the output may appear garbled).