From the zero-learning python Hello World_python

The simple ' Hello world! '

Python command line

If you've already installed Python, enter it on the Linux command line:

Copy Code code as follows:

$python

Will go directly to Python. Then, at the command line prompt >>> after, enter:

Copy Code code as follows:

>>>print (' Hello world! ')

You can see and then output on the screen:

Copy Code code as follows:

Hello world!

Print is a commonly used function that outputs a string in parentheses.

(in Python 2.x, print can also be a keyword that can be written in print ' Hello world! ', but it won't work in 3.x)
Write a little program

Another way to use Python is to write a Python program. Write a. py end file, such as hello.py, with a text editor

Write the following in hello.py and save:

Copy Code code as follows:

Print (' Hello world! ')

Exit the text editor, and then enter at the command line:

Copy Code code as follows:

$python hello.py

To run hello.py. You can see Python then output

Copy Code code as follows:

Hello world!

Script

We can also change the Python program hello.py into an executable script that executes directly:

Copy Code code as follows:

#!/usr/bin/env python

Print (' Hello world! ')

The permissions for the above program need to be modified to be executable:

Copy Code code as follows:

chmod 755 hello.py

And then on the command line, enter

Copy Code code as follows:

./hello.py

You can run it directly.
Summarize

Print

Command-line mode: Run Python, enter commands at the command line, and execute.

Program mode: Write a Python program and run it.