Transfer: https: //blog.csdn.net/hou_manager/article/details/79555809
A, Python Introduction
Python Introduction
Python3 officially released in 2008, December 3, but there are still a lot of library use Python2.7, so the need to install both versions of the Mac inside, and Python district and systems used to separate it? Today is how to write correctly installed the first time, and switch the default version of Python do not misuse the system.
Second, the installation
STEP 1 install Xcode
After installation is complete install Xcode command line tool
xcode-select --install
STEP 2 to install Homebrew
You can refer to the official website or directly insert:
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
STEP 3 Installing Python
The next step to officially enter the installation of the Python!
First, enter
python --version
This is a Python Mac system you want to use, do not move it. So now we have to use Python to install homebrew own use.
Python use homebrew search
brew search python
start installation:
brew install python
python3 successful installation
If you want to install python2, execute the following command
brew install python@2
It represents the successful installation of python
Check the installation directory
open /usr/local/Cellar
STEP 4 route setting the PATH $ (without interference and system Python)
What is the path to $ PATH it?
Remember when we installed Python, enter the brew,
the system will automatically know to begin to run homebrew.
The system in the end how to know where we brew in?
This is the purpose of the $ PATH!
echo $PATH
as the picture shows
Semi-colon (:) is the separator means
so when you enter the brew when the terminal inside
the system will start from / usr / bin to start looking
if found in / usr / bin, then there
will be a down / bin to search, and so on
Now, we return to the folder to see the
brew in fact, in / usr / local / bin inside
So the question is, the system in / usr / bin and there was a Python
now we are in / usr / local / Cellar which also installed Python
so that when the terminal marked with the python command, who would it be open?
Because sequential path, it will first find the system Python
'm going to solve this problem
sudo emacs /etc/paths
Let's get administrator privileges sudo
with the emacs editor program file path
terminal will be asked to enter a password
If this is not the order, adjusted to this order.
control + k: the cut out word line
control + y: Paste the word
control + x + s: Save
control + x + c: turn off emacs
Then, restart the terminal will see the change, call back
echo $PATH
STEP 5 the installation is completed, the check result
这样就完成啰！
其实python3本身比较不会跟其他人打架