how to change default python version

Question

I have installed python 3 2 in my mac  After I run  Applications Python 3 2 Update Shell Profile command  it s confusing that when I type python -V in Terminal it says that Python 2 6 1  how can I change the default python version

User · Answer

you can change temporarily or switch between different versions using following commands  set path C  Users Shaina AppData Local Programs Python Python35-32  PATH  python --version

User · Answer

Change the  default  Python by putting it ahead of the system Python on your path  for instance   export PATH  usr local bin  PATH

User · Answer

Navigate to   My Computer -  Properties -  Advanced -  Environment Variables -  System Variables  Suppose you had already having python 2 7 added in path variable and you want to change default path to python 3 x  then add path of python3 5 x folder before python2 7 path   open cmd  type  python --version   python version will be changed to python 3 5 x

User · Answer

In short  change the path in Environment Variables   For Windows     Advanced System Settings  gt  Advance  tab   On bottom you ll find  Environment Variables  Double-click on the Path  You ll see path to one of the python installations  change that to path of your desired version

User · Answer

sudo mv  usr bin python  usr bin python2 sudo ln -s   which python3   usr bin python   This will break scripts  but is exactly the way to change python  You should also rewrite the scripts to not assume python is 2 x  This will work regardless of the place where you call system or exec

User · Answer

Do right thing  do thing right   --- Zero Open your terminal   --Firstly input python -V  It likely shows   Python 2 7 10   -Secondly input python3 -V  It likely shows   Python 3 7 2   --Thirdly input where  python or which python  It likely shows    usr bin python   ---Fourthly input where python3 or which python3  It likely shows    usr local bin python3   --Fifthly add the following line at the bottom of your PATH environment variable file in    profile file or    bash profile under Bash or    zshrc under zsh   alias python   usr local bin python3    OR  alias python python3   -Sixthly input source    bash profile under Bash or source    zshrc under zsh   --Seventhly Quit the terminal   ---Eighthly Open your terminal  and input python -V  It likely shows    Python 3 7 2   I had done successfully try it   Others  the    bash profile under zsh is not that    bash profile    The PATH environment variable under zsh instead    profile  or    bash file  via    zshrc   Help you guys

User · Answer

Check the location of python 3    which python3  usr local bin python3   Write alias in bash profile  vi    bash profile   alias python   usr local bin python3    Reload bash profile  source    bash profile   Confirm python command    python --version Python 3 6 5

User · Answer

Check the execution path of python3 where it has libraries    which python3  usr local bin python3  some OS might have  usr bin python3   open bash profile file and add an alias  vi    bash profile   alias python   usr local bin python3  or alias python   usr bin python3    Reload bash profile to take effect of modifications  source    bash profile   Run python command and check whether it s getting loading with python3    python --version Python 3 6 5

User · Answer

Set Python 3 5 with higher priority sudo update-alternatives --install  usr bin python python  usr bin python2 7 1 sudo update-alternatives --install  usr bin python python  usr bin python3 5 2  Check the result sudo update-alternatives --config python python -V

User · Answer

On Mac OS X using the python org installer as you apparently have  you need to invoke Python 3 with python3  not python   That is currently reserved for Python 2 versions   You could also use python3 2 to specifically invoke that version     which python  usr bin python   which python3  Library Frameworks Python framework Versions 3 2 bin python3   cd  Library Frameworks Python framework Versions 3 2 bin    ls -l total 384 lrwxr-xr-x  1 root  admin      8 Apr 28 15 51 2to3  - gt  2to3-3 2 -rwxrwxr-x  1 root  admin    140 Feb 20 11 14 2to3-3 2  lrwxr-xr-x  1 root  admin      7 Apr 28 15 51 idle3  - gt  idle3 2 -rwxrwxr-x  1 root  admin    138 Feb 20 11 14 idle3 2  lrwxr-xr-x  1 root  admin      8 Apr 28 15 51 pydoc3  - gt  pydoc3 2 -rwxrwxr-x  1 root  admin    123 Feb 20 11 14 pydoc3 2  -rwxrwxr-x  2 root  admin  25624 Feb 20 11 14 python3  lrwxr-xr-x  1 root  admin     12 Apr 28 15 51 python3-32  - gt  python3 2-32 lrwxr-xr-x  1 root  admin     16 Apr 28 15 51 python3-config  - gt  python3 2-config -rwxrwxr-x  2 root  admin  25624 Feb 20 11 14 python3 2  -rwxrwxr-x  1 root  admin  13964 Feb 20 11 14 python3 2-32  lrwxr-xr-x  1 root  admin     17 Apr 28 15 51 python3 2-config  - gt  python3 2m-config -rwxrwxr-x  1 root  admin  25784 Feb 20 11 14 python3 2m  -rwxrwxr-x  1 root  admin   1865 Feb 20 11 14 python3 2m-config  lrwxr-xr-x  1 root  admin     10 Apr 28 15 51 pythonw3  - gt  pythonw3 2 lrwxr-xr-x  1 root  admin     13 Apr 28 15 51 pythonw3-32  - gt  pythonw3 2-32 -rwxrwxr-x  1 root  admin  25624 Feb 20 11 14 pythonw3 2  -rwxrwxr-x  1 root  admin  13964 Feb 20 11 14 pythonw3 2-32    If you also installed a Python 2 from python org  it would have a similar framework bin directory with no overlapping file names  except for 2to3      open  Applications Python  2 7 Update  Shell  Profile command   sh -l   echo  PATH  Library Frameworks Python framework Versions 2 7 bin  Library Frameworks Python framework Versions 3 2 bin  usr bin  bin  usr sbin  sbin  usr local bin   which python3  Library Frameworks Python framework Versions 3 2 bin python3   which python  Library Frameworks Python framework Versions 2 7 bin python   cd  Library Frameworks Python framework Versions 2 7 bin   ls -l total 288 -rwxrwxr-x  1 root  admin    150 Jul  3  2010 2to3  lrwxr-x---  1 root  admin      7 Nov  8 23 14 idle  - gt  idle2 7 -rwxrwxr-x  1 root  admin    138 Jul  3  2010 idle2 7  lrwxr-x---  1 root  admin      8 Nov  8 23 14 pydoc  - gt  pydoc2 7 -rwxrwxr-x  1 root  admin    123 Jul  3  2010 pydoc2 7  lrwxr-x---  1 root  admin      9 Nov  8 23 14 python  - gt  python2 7 lrwxr-x---  1 root  admin     16 Nov  8 23 14 python-config  - gt  python2 7-config -rwxrwxr-x  1 root  admin  33764 Jul  3  2010 python2 7  -rwxrwxr-x  1 root  admin   1663 Jul  3  2010 python2 7-config  lrwxr-x---  1 root  admin     10 Nov  8 23 14 pythonw  - gt  pythonw2 7 -rwxrwxr-x  1 root  admin  33764 Jul  3  2010 pythonw2 7  lrwxr-x---  1 root  admin     11 Nov  8 23 14 smtpd py  - gt  smtpd2 7 py -rwxrwxr-x  1 root  admin  18272 Jul  3  2010 smtpd2 7 py

User · Answer

According to a quick google search  this update only applies to the current shell you have open  It can probably be fixed by typing python3  as mac and linux are similar enough for things like this to coincide  Link to the result of google search   Also  as ninjagecko stated  most programs have not been updated to 3 x yet  so having the default python as 3 x would break many python scripts used in applications

User · Answer

In my case  on my Mac OSX  with Python 2 7 18 installed via mac ports  I was able to set the python version to 2 7 with    sudo port select --set python python27  So    python -V Python 2 7 18

User · Answer

This is probably desirable for backwards compatibility   Python3 breaks backwards compatibility  and programs invoking  python  probably expect python2  You probably have many programs and scripts which you are not even aware of which expect python python2  and changing this would break those programs and scripts   The answer you are probably looking for is You should not change this   You could  however  make a custom alias in your shell  The way you do so depends on the shell  but perhaps you could do alias py python3  If you are confused about how to start the latest version of python  it is at least the case on Linux that python3 leaves your python2 installation intact  due to the above compatibility reasons   thus you can start python3 with the python3 command

User · Answer

Old question  but alternatively   virtualenv --python python3 5  venv source  venv bin activate

User · Answer

I am using OS X 10 7 5 and Python 3 4 2  If you type python3 and what you want to run it will run it using python 3  For example  pyhton3 test001 py  That ran a test program I made called test001  I hope this helps

[python] how to change default python version?

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