Corrections to Lecture 2

The time command does not return the time (date does that as well as returning the date). Rather, it is used to "time a simple command or give resource usage."
Here is a reasonable description and example of Unix hard vs. soft links -- it might be confusing, especially the discussion of iNodes, but the examples should be reasonably clear.
Here are some basic commands to try (taken roughly from description/example link in the bullet above) to get some sense of the differences between hard and soft links (note, some of the commands fail, but that's part of what's important about the example).

$
echo "1111" > x

$ ln x y

$ cat x

$ cat y

$ echo "2222" >> y

$ cat x

$ cat y

$ rm x

$ cat x

$ cat y

$ ln y x

$ ln -s x z

$ echo "33333" >> x

$ cat x

$ cat y

$ cat z

$ rm x

$ cat x

$ cat y

$ cat z