第945页 | Learning Python | 阅读 ‧ 电子书库

Is Python Already Present?

Before you do anything else, check whether you already have a recent Python on your machine. If you are working on Linux, Mac OS X, or some Unix systems, Python is probably already installed on your computer, though it may be one or two releases behind the cutting edge. Here’s how to check:

 

On Windows, check whether there is a Python entry in the Start button’s All Programs menu (at the bottom left of the screen). On Mac OS X, open a Terminal window (Applications→Utilities→Terminal) and type python at the prompt. On Linux and Unix, type python at a shell prompt (a.k.a. terminal window), and see what happens. Alternatively, try searching for “python” in the usual places—/usr/bin, /usr/local/bin, etc.

If you find a Python, make sure it’s a recent version. Although any recent Python will do for most of this text, this edition focuses on Python 3.0 and 2.6 specifically, so you may want to install one of these to run some of the examples in this book.

Speaking of versions, I recommend starting out with Python 3.0 or later if you’re learning Python anew and don’t need to deal with existing 2.X code; otherwise, you should generally use Python 2.6. Some popular Python-based systems still use older releases, though (2.5 is still widespread), so if you’re working with existing systems be sure to use a version relevant to your needs; the next section describes locations where you can fetch a variety of Python versions.