Reworking Chapter 7

I had already made it through most of chapter 7 assignments over the weekend--well at least up to the problem one  in 7.8 with very little issues.  I was already rather familiar with diff from last semester and using it as described in 7.2 & 7.4 gave me the results that I expected it would.  I got tripped up a little in 7.5 with the subversion aspect of it, but I was able to back up and make sense of my error and move toward where I would eventually get stuck.  No it was not the patches in 7.6 or 7.7--which we've already finished, but with 7.8.  First of all, I was totally confused with the instructions.  After reading it several times, I looked through several of my classmate's blogs and saw that I was not the only one.  The whole first sentence throws me and the way I understand it, I'm supposed to have a file named "bar" with some data in it; then my patch file creates a file named "foo" which will have a copy of the contents in "bar."  I worked on this angle, but didn't have any success.  I could have two files "foo" and "bar" with contents in them and can combine them with the patch (and diff them of course) but really never was able to do what I think 7.8 is asking me to.  I'll pay close attention today to how other's handled this problem!