python, django version selection, python installation under linux

Article directory

• 1. Python version selection
• • Comparison between Django version and Python version
• 2. python installation under linux
• • ubuntu20.04 installation
  • centos8 compilation and installation of Python 3.8.10
  • • Compilation process Problems encountered in
    • • Prompt that the compilation was successful ， some modules were not compiled properly
      • The _ctypes module is missing
    • Create a virtual environment

1. Python version selection

Official download address：https://www.python.org/downloads/

First of all, Python2.x and Python3 .x options – These are the two big versions. Currently, version updates and technical support for Python 2.x have been officially stopped. The last version of Python2.x is Python2.7.18 released in 2020.

Python 3.x is not a simple upgrade of Python 2.x. In order not to bring too much burden, Python 3.x was not designed with backward compatibility in mind. Therefore ，If it is not the maintenance of old code，our new code is recommended to use Python3.x.

ok，The next step is Python3.x. How do we choose?

Let’s look at the official python 3.8.14 description first
Note：The version you are viewing Is Python 3.8.13 – It is a security bug fix version of the older 3.8 series. Python 3.10 is now the latest feature release series for Python 3.

For example：According to the release calendar specified in PEP 569，Python 3.8 is now in the “Security Fixes Only” phase of its lifecycle：3.8 The branch only accepts security fixes，and these fixes will be released in source code only form from time to time until October 2024. Python 3.8 no longer receives general bug fixes， and a binary installer is no longer provided for it. Python 3.8.10 is the last complete bug-fix release of Python 3.8，with a binary installer.

You can see that Python 3.8 “officially no longer provides a binary installer” and only fixes security issues in source code.

Let’s look at the official python 3.9.14 again
Note：The version you are viewing is Python 3.9.14，It is the old version of the 3.9 series Security bug fix release.

No installer
According to the release calendar specified in PEP 596，Python 3.9 is now in the “Security Fixes Only” phase of its lifecycle：The 3.9 branch only accepts security fixes ，And will be released in source code only form from time to time until October 2025. Python 3.9 no longer receives regular bug fixes and a binary installer is no longer provided for it. Python 3.9.13 is the last complete bug-fix release of Python 3.9 with a binary installer.

Summary：The latest version is 3.10.x，The previous versions only fix security issues，If there are security issues，we need Download the latest source code to compile and use the fix.

Overall, it’s not a big problem. If you take into account the stability issues of the latest version and the compatibility issues of some common frameworks and python versions&#xff0c ;We will use versions 3.8 and 3.10，Compile with source code！

The default Python version of Ubuntu 20.04 LTS is 3.8.10.
Ubuntu 22.04 LTS (Jammy Jellyfish). However, the default Python 3 version of this version is Python 3.10, which is higher than the 3.9, 3.8 or even earlier versions that many developers are using.

Comparison between Django version and Python version

Official link：https://www.djangoproject.com/download/

Django is open source under the BSD license. We recommend using the latest version of Python 3. The last version to support Python 2.7 was Django 1.11 LTS. For information on which Python versions each version of Django supports, see the FAQ.

Personal work skills：After we select python， we just use pip to install django and various dependencies，without the version number，In this way, basically all dependencies are and Currently Python is the most compatible match.

2. python installation under linux

ubuntu20.04 installation

Ubuntu 20.04 LTS default Python version for 3.8.10.
Ubuntu 22.04 LTS (Jammy Jellyfish). However, the default Python 3 version of this version is Python 3.10, which is higher than the 3.9, 3.8 or even earlier versions that many developers are using.

3.8.10 is still more mainstream，It is recommended to use the default！

centos8 compile and install Python 3.8.10

In Building a Python3.8 operating environment on CentOS8
Reference URL: https://www.modb.pro/db/144965
Detailed tutorial on installing Python3.8 on Centos7
Reference URL: https:// blog.csdn.net/u010786653/article/details/122690588

1. Follow the dependencies needed to compile python：

sudo yum -y install gcc gcc -c++ zlib-devel bzip2-devel openssl- devel sqlite-devel readline-devel libffi-devel
sudo yum install zlib-devel bzip2-devel openssl- devel ncurses-devel sqlite-devel readline-devel tk-devel xz-devel gdbm-devel


2. Download python to the temporary directory

VERSION&#61 ;3.8.10
wget -P /tmp/ https://www.python .org/ftp/python/${VERSION}/Python-${VERSION}.tgz


Download to the temporary directory to compile，

tar -xvzf /tmp/Python-${VERSION}.tgz -C /tmp/
cd /tmp/Python-${VERSION}


3. Compile

Specify the installation directory as $HOME/python3（This step will take a long time）

mkdir -p $HOME/python3
#./configure --prefix=/usr/local/python3
./configure --prefix= $HOME/python3 --enable-optimizations


–enable-optimizations option is tested by running multiple times&#xff0c ; to optimize Python binaries. This will make the build process slower.

nproc
make -j 8


Modify to correspond to the number of cores in the processor. You can find your processor core count by running nproc.
PS: The nproc command can display the number of CPUs available to the current process，This number may be less than the actual number of jobs

After the generation process is completed，Install the Python binaries（ Please do not use the standard make install as it will overwrite the default system Python binaries.

sudo make altinstall


The difference between make altinstall and make install， altinstall skips creating the python link and the manual pages links.
altinstall skips creating python links and man page links.
If you use make install，there will be two different versions of Python in the /usr/bin/ directory on the system，This will cause many problems.
Therefore, we can solve this problem by configuring the compilation and installation path in configure.

Summary：If our compilation parameters do not configure the installation path，If we use the default installation path，, we need to use make altinstall. So generally when there are multiple versions ， we just use make altinstall directly！

Problems encountered during the compilation process

Tips Compiled successfully，Some modules were not compiled yet

Python build finished successfully! #Prompt installation successful
The necessary bits to build these optional modules were not found:
_dbm _gdbm _lzma
_tkinter nis

yum install zlib-devel bzip2-devel openssl-devel ncurses -devel sqlite-devel readline-devel tk-devel xz-devel gdbm-devel


Missing _ctypes module

There is a built-in in python3 The module is called ctypes， It is an external function library module of python3， Provides data types compatible with C language， and calls the shared library under Linux system through it，This module You need to use the development link library (header file and link library) of the foreign function library (Foreign function library) in the centos7 system – but the development link library package of the external function library (libffi) is not installed in the centos7 system.

Install libffi package

yum install libffi-devel

Create a virtual environment

Python virtual environment is a self-contained Directory tree which contains the Python installation and a number of other packages. It allows you to install Python modules in an isolated location for a specific project rather than installing them globally. This way you don’t have to worry about affecting other Python projects.

In this example ，we will create a new Python 3.8 project，called in the user’s home directory. my_app

First，create the project directory and switch to：

mkdir ~/my_app && cd ~/my_app


Run the following command from inside the project root to create a file named ：my_app_venv

python3.8 -m venv my_app_venv


Activate environment：

source my_app_venv/bin/activate


After activation, the shell prompt will be prefixed with the environment name. Starting with Python 3.4 – when creating a virtual environment – Python’s package manager pip will be installed by default.

span> ~/my_app && cd ~/my_app

Run the following command from inside the project root to create a file called ：my_app_venv

python3.8 -m venv my_app_venv


Activate environment：

source my_app_venv /bin/activate


After activation, the shell prompt will be prefixed with the environment name. Starting with Python 3.4 – when creating a virtual environment – Python’s package manager pip will be installed by default.