Initial settings for using Python3.8 and pip on CentOS8

yum and dnf

From CentOS8, unlike up to 7, the ** yum command is not used. ** ** You can use yum by pushing it, but we don't recommend it. We will use the successor ** dnf command. ** **

Basically, you can use it in almost the same way as the yum command. What's the difference is ...

--The yum command runs on Python 2 series --The dnf command runs on Python 3 series

Is it inevitable to try to work with Python 3 system? If you want to know more details, please follow the link below.

Install Python 3.8

$ sudo dnf install python38 -y

Commentary

• sudo --A magical trick that lets the administrator execute commands
• dnf --Successor to yum mentioned above
• install --Magic to install
• python38 --Specify the package name you want to install (for Python, python2, python36, python38, etc.)
• -y --Returns all y to y / n? That appears after execution

As you can see from the command again, it's not much different from the yum command.

Check Python 3.8 version

//Either way
$ python3.8 --version 
Python 3.8.0
$ python3.8 -V
Python 3.8.0

Commentary

• python3.8 --The version selected as standard in python is called, but you can call any version by specifying the version like python3.8 (If you want to see which version is in your environment, up to python You can see it by pressing the Type Tab key twice.)
• --version --This is an option to output the version (-V can also be used on your behalf)
• -V --This is an option to output the version (--version can also be used on your behalf)

Check pip version

//Either way
$ pip3.8 --version
pip 19.2.3 from /usr/lib/python3.8/site-packages/pip (python 3.8)
$ pip3.8 -V
pip 19.2.3 from /usr/lib/python3.8/site-packages/pip (python 3.8)

Commentary

• pip3.8 --Similar to python, you can specify the version. Also, pip comes with the corresponding version by installing python. ---- version and -V are the same as above

To run Python 3.8 in Python

It's a shame that you have to specify the version every time, so we will set it to use 3.8 by default.

$ alternatives --config python

There are 3 programs'python'To provide.

Select command
-----------------------------------------------
*+ 1           /usr/libexec/no-python
   2           /usr/bin/python3
   3           /usr/bin/python3.8

Press Enter to select the current[+]Or enter the selection number: 3 //Enter the corresponding numerical value according to the environment you want to select

Commentary

• alternatives --It is a command that can switch standard commands etc. (It feels like you can select the default application of Windows)
• --config --You can change the settings
• python --By specifying the package name in this part, the programs of that package will be listed.

From the programs listed in the command section, select the program you want to use as standard and enter the number. This will run 3.8 python with python only, instead of the command you used to type python3.8

To run pip3.8 with pip

You can't change it with the python3.8-> python procedure and you will have to use a different command

$ sudo update-alternatives --install /usr/bin/pip pip /usr/bin/pip3.8 1

Commentary

• update-alternatives --You can change the name of the command (apparent name)
• --install --Add to the package group listed by alternatives etc.
• /usr/bin/pip --Specify the destination of the symbolic link in this part (pip this time)
• pip ――I think this part is the name of the program, but I don't know in detail, so I'd appreciate it if you could comment.
• /usr/bin/pip3.8 --Specify the location where the program you want to add is actually stored (pip3.8 this time)
• 1 ――I don't know this part in detail either. I'd be grateful if you could comment ...

important point

It happened when I was trying to set pip by myself, so be careful, but be aware that the directory displayed by the following command is not the directory actually specified by update-alternatives.

$ pip3.8 -V
pip 19.2.3 from /usr/lib/python3.8/site-packages/pip (python 3.8)

Afterword

With the above steps, you can safely handle python and pip. This will make it easier to study Ansible ...

Twitter