对于Linux来说，Python一般是默认就安装了的：

[root@center-me ~]# whereis python
python: /usr/bin/python /usr/bin/python2.7 /usr/lib/python2.7 /usr/lib64/python2.7 /usr/include/python2.7 /usr/share/man/man1/python.1.gz
[root@center-me ~]#

你可以通过下面的命令去查看一下你系统当前的Python的版本情况：

[root@center-me ~]# python -V
Python 2.7.5
[root@center-me ~]#

打印“Hello world”：

交互方式：

[root@center-me python]# python
Python 2.7.5 (default, Jun 17 2014, 18:11:42) 
[GCC 4.8.2 20140120 (Red Hat 4.8.2-16)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> print 'hello world'
hello world
>>>

写到源码文件里面：

[root@center-me python]# cat hello_world.py 
#!/usr/bin/python
print 'Hello world'
[root@center-me python]# 
[root@center-me python]# python hello_world.py 
Hello world
[root@center-me python]#

或者这样执行：

[root@center-me python]# ls -ltr *
-rw-r--r-- 1 root root 107 Mar  3 11:03 array.py
-rw-r--r-- 1 root root  38 Mar 30 14:05 hello_world.py
[root@center-me python]# 
[root@center-me python]# chmod a+x hello_world.py 
[root@center-me python]# 
[root@center-me python]# ls -ltr *
-rw-r--r-- 1 root root 107 Mar  3 11:03 array.py
-rwxr-xr-x 1 root root  38 Mar 30 14:05 hello_world.py
[root@center-me python]# 
[root@center-me python]# ./hello_world.py 
Hello world
[root@center-me python]#

获得帮助：

[root@center-me python]# python
Python 2.7.5 (default, Jun 17 2014, 18:11:42) 
[GCC 4.8.2 20140120 (Red Hat 4.8.2-16)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> help('print');
The ``print`` statement
***********************

   print_stmt ::= "print" ([expression ("," expression)* [","]]
                  | ">>" expression [("," expression)+ [","]])

``print`` evaluates each expression in turn and writes the resulting
object to standard output (see below).  If an object is not a string,
it is first converted to a string using the rules for string
conversions.  The (resulting or original) string is then written.  A
space is written before each object is (converted and) written, unless
the output system believes it is positioned at the beginning of a
line.  This is the case (1) when no characters have yet been written
to standard output, (2) when the last character written to standard
output is a whitespace character except ``' '``, or (3) when the last
write operation on standard output was not a ``print`` statement. (In
some cases it may be functional to write an empty string to standard
output for this reason.)

Note: Objects which act like file objects but which are not the built-in
  file objects often do not properly emulate this aspect of the file
  object's behavior, so it is best not to rely on this.

A ``'\n'`` character is written at the end, unless the ``print``
statement ends with a comma.  This is the only action if the statement
contains just the keyword ``print``.

Standard output is defined as the file object named ``stdout`` in the
built-in module ``sys``.  If no such object exists, or if it does not
have a ``write()`` method, a ``RuntimeError`` exception is raised.

``print`` also has an extended form, defined by the second portion of
the syntax described above. This form is sometimes referred to as
"``print`` chevron." In this form, the first expression after the
``>>`` must evaluate to a "file-like" object, specifically an object
that has a ``write()`` method as described above.  With this extended

>>>

————————————
Done。