Most versions of Linux and UNIX, including Mac OS X, come with Python preinstalled. This is partially for convenience because it is such a popular scripting language—and it saves having to install it later if the user wants to run a script—and partially because many vital or useful programs included in Linux distributions are written in Python. For example, the Ubuntu Software Center is a Python program.
The Python binary is installed into
/usr/bin/python3); if you run that, you enter the Python interactive interpreter where you can type commands and have them executed immediately. Although PHP also has an interactive mode (use
a to activate it), it is neither as powerful nor as flexible as Python’s. ...