That brings us to the end of the lesson. We began by looking at Python's powerful slicing operation,
which allows us to extract parts of strings, lists, and tuples. We saw how to generate a parser to handle
a realistic command line grammar with multiple options using optargs.
We saw how to access environment variables using the dictionary called environ and the getenv function both
from the os module. We talked about file-like objects and saw how Python provides access to the streams
stdin, stdout, and stderr. And we built a couple of filters--Tac, a backwards version of cat,
and a simplified version of Grep. Finally, we learned about signals, what they are, how to ignore them,
and how to usefully handle them.
Coming up in the less lesson, our focus will be on using Python in conjunction with other tools.
We'll see how to run external commands and how to talk to them through pipes, in effect building Python
wrappers around existing tools. We'll use Python modules to handle common file formats, notably tar.
And we'll see how to send mail messages. All good stuff. I'll see you there.