Unable to set default python version to python3 in ubuntu

Question

I was trying to set default python version to python3 in Ubuntu 16 04  By default it is python2  2 7   I followed below steps      update-alternatives --remove python  usr bin python2 update-alternatives --install  usr bin python python  usr bin python3   but I m getting the following error for the second statement       rejeesh rejeesh-Vostro-1015    update-alternatives --install  usr bin python python  usr bin python3 update-alternatives  --install needs  lt link gt   lt name gt   lt path gt   lt priority gt   Use  update-alternatives --help  for program usage information       I m new to Ubuntu and Idon t know what I m doing wrong

User · Answer

Do   cd   gedit  bash aliases   then write either  alias python python3   or   alias python   usr bin python3    Save the file  close the terminal and open it again  You should be fine now  Link

User · Answer

The second line mentioned can be changed to update-alternatives --install  usr bin python python  usr bin python3 10 This gives a priority of 10 for the path of python3  The disadvantage of editing  bashrc file is that it will not work while using the commands with sudo  Update  Please use sudo while running the command like this  sudo update-alternatives --install  usr bin python python  usr bin python3 10

User · Answer

As an added extra  you can add an alias for pip as well  in  bashrc or bash aliases         alias pip  pip3      You many find that a clean install of python3 actually points to python3 x so you may need        alias pip  pip3 6    alias python  python3 6

User · Answer

To change to python3  you can use the following command in terminal alias python python3

User · Answer

A simple safe way would be to use an alias  Place this into    bashrc file  if you have gedit editor use  gedit    bashrc  to go into the bashrc file and then at the top of the bashrc file make the following change   alias python python3  After adding the above in the file  run the below command  source    bash aliases or source    bashrc  example     python --version Python 2 7 6   python3 --version Python 3 4 3   alias python python3   python --version Python 3 4 3

User · Answer

To change Python 3 6 8 as the default in Ubuntu 18 04 to Python 3 7  Install Python 3 7 Steps to install Python3 7 and configure it as the default interpreter   Install the python3 7 package using apt-get sudo apt-get install python3 7  Add Python3 6  amp  Python 3 7 to update-alternatives   sudo update-alternatives --install  usr bin python3 python3  usr bin python3 6 1 sudo update-alternatives --install  usr bin python3 python3  usr bin python3 7 2   Update Python 3 to point to Python 3 7 sudo update-alternatives --config python3 Enter 2 for Python 3 7  Test the version of python   python3 --version Python 3 7 1

User · Answer

To change Python 3 6 8 as the default in Ubuntu 18 04 from Python 2 7 you can try the command line tool update-alternatives  sudo update-alternatives --config python  If you get the error  quot no alternatives for python quot  then set up an alternative yourself with the following command  sudo update-alternatives --install  usr bin python python  usr bin python3 2  Change the path  usr bin python3 to your desired python version accordingly  The last argument specified it priority means  if no manual alternative selection is made the alternative with the highest priority number will be set  In our case we have set a priority 2 for  usr bin python3 6 8 and as a result the  usr bin python3 6 8 was set as default python version automatically by update-alternatives command  we can anytime switch between the above listed python alternative versions using below command and entering a selection number  update-alternatives --config python

User · Answer

Just follow these steps to help change the default python to the newly upgrade python version  Worked well for me     sudo apt-install python3 7 Install the latest version of python you want cd  usr bin  Enter the root directory where python is installed sudo unlink python or sudo unlink python3   Unlink the current default python sudo ln -sv  usr bin python3 7 python Link the new downloaded python version python --version Check the new python version and you re good to go

User · Answer

get python path from  ls  usr bin python    then set your python version  alias python   usr bin python3

User · Answer

You didn t include the priority argument sudo update-alternatives --install  usr bin python python  usr bin python3 5  You can replace 5 with any priority you want  A higher priority alternative takes precedence over lower priority

User · Answer

As it says  update-alternatives --install needs  lt link   lt name   lt path  and  lt priority  arguments   You have link   usr bin python   name  python   and path   usr bin python3   you re missing priority   update-alternatives --help says       lt priority gt  is an integer  options with higher numbers have higher priority in automatic mode    So just put a 100 or something at the end

User · Answer

Simply remove python-is-python2   sudo apt purge python-is-python2   And install python-is-python3   sudo apt install python-is-python3   It will automate the process of transition to new python3  Optionally you can get rid of remaining packages later   sudo apt autoremove  amp  amp  sudo apt autoclean

User · Answer

If you have Ubuntu 20 04 LTS  Focal Fossa  you can install python-is-python3  sudo apt install python-is-python3  which replaces the symlink in  usr bin python to point to  usr bin python3

User · Answer

This is a simple way that works for me  sudo ln -s  usr bin python3  usr bin python  You could change  usr bin python3 for your path to python3  or the version you want   But keep in mind that update-alternatives is probably the best choice

User · Answer

At first  Make sure Python3 is installed on your computer  Go to your terminal and type   cd     to go to your home directory  If you didn t set up your  bash profile yet  type touch  bash profile to create your  bash profile   Or  type open -e  bash profile to edit the file   Copy and save alias python python3 in the  bash profile    Close and reopen your Terminal  Then type the following command to check if Python3 is your default version now   python --version  You should see python 3 x y is your default version   Cheers

User · Answer

The best way in ubuntu 18 04 which will work for all users is  sudo vim  etc bash bashrc add lines alias python python3 alias pip pip3   Save the changes and restart          After restart what ever version of python 3 you have in the system along with python 2 7 will be taken as default  You could be more specific by saying the following in alias if you have multiple version of python 3   sudo vim  etc bash bashrc add lines alias python python3 6 alias pip pip3 6

User · Answer

For another non-invasive  current-user only approach     First  make  HOME bin  which will be automatically added to user s PATH mkdir -p   bin   make link actual python binaries ln -s   which python3  python ln -s   which pip3  pip   python pip will be ready in a new shell

User · Answer

EDIT  I wrote this when I was young an naive  update-alternatives is the better way to do this  See  Pardhu s answer   Open your  bashrc file nano    bashrc  Type alias python python3 on to a new line at the top of the file then save the file with ctrl o and close the file with ctrl x  Then  back at your command line type source    bashrc  Now your alias should be permanent

User · Answer

Set priority for default python in Linux terminal by adding this  sudo update-alternatives --install  usr bin python python  usr bin python3 10 sudo update-alternatives --install  usr bin python python  usr bin python2 1  Here  we set python3 to have priority 10 and python2 to priority 1  This will make python3 the default python  If you want Python2 as default then make a priority of python2 higher then python3

User · Answer

At First Install python3 and pip3  sudo apt-get install python3 python3-pip   then in your terminal run   alias python python3   Check the version of python in your machine   python --version

[python] Unable to set default python version to python3 in ubuntu

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