Python2 notes (1)-install and run Helloworld

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installation

Configuration

Environment variable configuration

Programs and executable files can be in many directories, and these paths are probably not in the search path provided by the operating system for executable files.

path (path) is stored in an environment variable, which is a named string maintained by the operating system. These variables contain information about available command line interpreters and other programs.

The path variable in Unix or Windows is PATH (UNIX is case sensitive, Windows is not case sensitive).

In Mac OS, the python installation path was changed during the installation process. If you need to reference Python in other directories, you must add the Python directory to the path.

Setting environment variables on Unix / Linux

• In the csh shell:

  Input

  setenv PATH "$PATH:/usr/local/bin/python"
  

  , Press "Enter".

• In the bash shell (Linux):
  enter

  export PATH="$PATH:/usr/local/bin/python" 
  

  And press "Enter".

• In sh or ksh shell:

  Input

  PATH="$PATH:/usr/local/bin/python" 
  

  , Press "Enter".

  Note: / usr / local / bin / python is the installation directory of Python.

Setting environment variables in Windows

Add the Python directory in the environment variable:

• In the command prompt box (cmd):

  Input

  path=%path%;C:\Python 
  

  And press "Enter".

  Note: C: \ Python is the installation directory of Python.

run

$ python

hello.py

print 'hello'

$ python hello.py