Python Basics Hello world!

Python command line

Assuming you have already installed Python, enter it on the Linux command line:

$ python

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

>>>print (' Hello World ')

You can see it and then output it on the screen:

Hello world!

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

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

Write a small program

Another way to use Python is to write a Python program that uses a text editor to write a. py file that ends with, say, hello.py

Write the following in hello.py, and Save:

Print (' Hello world! ')

Exit the text editor and enter it at the command line:

$python hello.py

To run hello.py. You can see that Python then outputs

Hello world!

Script

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

#！ /usr/bin/env python

Print (' Hello world ')

You need to modify the permissions of the above program to be executable:

chmod 755 hello.py

Then, on the command line, enter

./hello.py

Summarize

Print

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

Program mode: Write a Python program and run it.

Python Basics Hello world!