The debian I am using has its default python3 -> 3.7.3.
Then I successfully installed the python3 version 3.7.4, which is a dedicated version I prefer to.
But now, the python version goes to mess.
Here is the detailed info from terminal commands
python3 --version
--> Python 3.7.4
/usr/bin/python3 -- version
--> Python 3.7.3
/usr/bin/python3.7 -- version
--> Python 3.7.3
So how can I align it with "Python 3.7.4"?
What AnsFourtyTwo said is correct, but if you need to manage multiple Python versions, try to use pyenv.
It's a tool that lets to manage multiple Python versions (and implementations) on your machine and switch between them easily so that you won't have to change the links manually.
It's similar to nvm (Node.js version manager).
If you have a look into /usr/bin, you will see, that you'll have many different executables for different python versions, e.g. python2.7, python3.7.3, python3.7.4, etc.
To give users the security of a known environment, you'll also find symbolic links, e.g.
lrwxrwxrwx 1 root root 9 Okt 18 2016 python -> python2.7*
lrwxrwxrwx 1 root root 9 Okt 18 2016 python2 -> python2.7*
-rwxr-xr-x 1 root root 3546104 Nov 19 10:35 python2.7*
...
lrwxrwxrwx 1 root root 9 Okt 18 2016 python3 -> python3.5*
-rwxr-xr-x 2 root root 4460336 Nov 17 20:23 python3.5*
So in the example the commands python and python2 will both execute python2.7. Calling python3 will actually execute python3.5.
I usually change those symbolic links to fit my needs (you might need root rights). For example, I usually want the command python to run the current python3 version:
cd /usr/bin
ln -sf python3 python
Why calling python3 --version results in version 3.7.4 must further be examined:
What does which python3 show?
Have you defined any aliases (e.g. alias python="/usr/bin/python3.7.4" in your .bashrc file)
When I type:
yum install google-cloud-sdk
I get an error saying that it requires a version of python greater than or equal to 2.7.
I do have 2.7 installed, but when I type python -V it says 2.6.6.
I am using CENTOS 6.10
How can I fix this error, and install the Google Cloud SDK?
One possible approach is to not rely on an OS-specific pre-packaged SDK which comes with dependencies that might hurt your ability to install/upgrade the SDK itself or its components at will (if using packages not built by Google, since you'd need to wait for those packages to become available).
For that you can just download the latest generic linux SDK (the google-cloud-sdk-<version>-linux-x86_64.tar.gz file) from Installing from versioned archives (or an older version from the archive GCS bucket if you want) - which you can unpack in a convenient location (personally I picked /usr/local). It is pretty self-contained, which allows to even have multiple SDK versions side by side - I did that and I can switch between versions at will using symlinks. This is how it looks like:
my_laptop:/usr/local> ls -la | grep google-cloud-sdk
lrwxrwxrwx 1 root root 20 Feb 26 22:30 google-cloud-sdk -> google-cloud-sdk-236
drwxr-xr-x 1 root root 342 Jun 14 2018 google-cloud-sdk-204
drwxr-xr-x 1 root root 342 Dec 17 2018 google-cloud-sdk-228
drwxr-xr-x 1 root root 342 Feb 26 22:33 google-cloud-sdk-236
And to not have to mess with the path I just symlinked the desired SDK executables from the current version into /usr/local/bin (which I already have in my path):
my_laptop:/usr/local/bin> ls -la | grep google-cloud-sdk
lrwxrwxrwx 1 root root 38 Aug 9 2016 gcloud -> /usr/local/google-cloud-sdk/bin/gcloud
lrwxrwxrwx 1 root root 38 Aug 9 2016 gsutil -> /usr/local/google-cloud-sdk/bin/gsutil
In general this should work on a wide variety of Linux variants (the versions I have installed worked just fine with my pretty archaic OpenSuSE 13.3 and survived a complete OS re-install to OpenSuSE Leap 15.0).
This approach should be completely opaque to your package manager (so don't try to upgrade using that) and can even be done as a regular user, not necessarily as root (if needed).
You probably still need to figure out your python version issue in order to use the SDK. If python -V it says 2.6.6 then you also have that version installed and it is the preferred one over 2.7. Your options:
uninstall python 2.6
invoke python using python2.7 instead of just python:
my_laptop:/usr/bin> python2.7 -V
Python 2.7.14
update your /usr/bin/python symlink to point to the version you desire:
my_laptop:/usr/bin> ls -la | grep python
lrwxrwxrwx 1 root root 9 Feb 6 13:04 python -> python2.7
lrwxrwxrwx 1 root root 9 Feb 6 13:04 python2 -> python2.7
-rwxr-xr-x 1 root root 6304 Feb 6 13:05 python2.7
lrwxrwxrwx 1 root root 9 Jan 31 11:36 python3 -> python3.6
-rwxr-xr-x 2 root root 10456 Jan 31 11:36 python3.6
I am using RHEL6 which came with Python 2.6.6 pre-installed on it as the default python executable.
Some months ago, I installed Python 2.7 on it and switched the default python version to 2.7 (yes, idiot move I now realize). So now when I type python it runs Python 2.7.
Also: which python gives me /usr/local/bin/python
As you might expect, and I only found out recently, this has caused issues when trying to run some system scripts which depend on the version being 2.6. The 2.6 installation still exists and I can run it by either python2 or python2.6.
Also: which python2 gives /usr/bin/python2 and which python2.6 gives /usr/bin/python2.6
The problem is that I do not remember how I switched the default version to 2.7. I know I didn't create any alias, because I can't find any in the ~/.bashrc file.
Does anyone have any advice on how I can revert back by changes so that Python 2.6.6 becomes the default once again? I can provide any further information that might be necessary to analyze this problem. Moreover, I have a couple of other people around me who are also using RHEL6 and haven't played around with their python installations, so if I need to copy any original scripts from /usr/bin/ to get this fixed I can get it from them, as long as I know what to get.
Thanks in advance for any advice!
Responses to Barun Sharma:
Running ls -l /usr/local/bin/python* gives me:
-rwxr-xr-x. 2 root root 6111394 Jan 16 2015 /usr/local/bin/python
-rwxr-xr-x. 2 root root 6111394 Jan 16 2015 /usr/local/bin/python2.7
-rwxr-xr-x. 1 root root 1624 Jan 16 2015 /usr/local/bin/python2.7-config
lrwxrwxrwx. 1 root root 9 Dec 26 2014 /usr/local/bin/python3 -> python3.4
-rwxr-xr-x. 2 root root 8777236 Dec 26 2014 /usr/local/bin/python3.4
lrwxrwxrwx. 1 root root 17 Dec 26 2014 /usr/local/bin/python3.4-config -> python3.4m-config
-rwxr-xr-x. 2 root root 8777236 Dec 26 2014 /usr/local/bin/python3.4m
-rwxr-xr-x. 1 root root 3013 Dec 26 2014 /usr/local/bin/python3.4m-config
lrwxrwxrwx. 1 root root 16 Dec 26 2014 /usr/local/bin/python3-config -> python3.4-config
lrwxrwxrwx. 1 root root 16 Jan 16 2015 /usr/local/bin/python-config -> python2.7-config
create a soft link:-
ln -s /usr/bin/python2 /usr/local/bin/python
Or directly point /usr/local/bin/python to your python2.6 binary(i.e where ~/usr/bin/python2` points).
Follow these steps:-
1) rm /usr/local/bin/python. This would remove the soft link. But python 2.7 will still be there. You can check /usr/local/bin/python2.7.
2) ln -s /usr/local/bin/python2.6 /usr/local/bin/python. Symbolic link from python to python2.6
Also when you are working on python, I would advise you to use virtual environment and install your required python version and other packages. I generally do not install packages to system python when it is required for a specific project(rather do it on a virtual env).
Once you have your system back to normal, the way to add new versions of Python 2.7, 3.3, or 3.4 to RHEL (6 or 7) is to utilize Software Collections (aka RHSCL or SCL) which install along side the original Python versions. There are many other languages, databases, web servers, and other tools, too. RHSCLs are included in most RHEL subscriptions.
To get started: http://developers.redhat.com/products/softwarecollections/overview/
You can also find information here: https://access.redhat.com/products/Red_Hat_Enterprise_Linux/Developer/#rhscl=&dev-page=5
OR here: http://developerblog.redhat.com/tag/software-collections/
Trying to get jenkins to work with anaconda python. I'm using the shiningpanda plugin and python plugin.
Whenever I try to set the python installation to point to my python 2.7 executable, /home/lminer/anaconda/bin/python2.7, I get the message that it is neither a directory nor an executable. Is there some 2.7 compatibility problem?
Edit:
Here's my python info
# which python
/home/lminer/anaconda/bin/python2
# ls -l /home/lminer/anaconda/bin/python*
lrwxrwxrwx 1 root root 7 Oct 9 17:02 /home/lminer/anaconda/bin/python -> python2
lrwxrwxrwx 1 root root 9 Oct 9 17:02 /home/lminer/anaconda/bin/python2 -> python2.7
-rwxr-xr-x 1 root root 10038 Oct 9 17:02 /home/lminer/anaconda/bin/python2.7
-rwxr-xr-x 1 root root 1600 Oct 9 17:02 /home/lminer/anaconda/bin/python-argcomplete-check-easy-install-script
-rwxr-xr-x 1 root root 1678 Oct 9 17:02 /home/lminer/anaconda/bin/python-config
Not sure how to give evidence on the error. I go to Jenkins > configuration > Python > Python Installations. Under Home or executable I put /home/lminer/anaconda/bin/python2.7, /home/lminer/anaconda/bin/python, /home/lminer/anaconda/bin/. And each time a message in red below the box reads: Neither a directory nor an executable
I don't get this issue if I instead point to /usr/bin/python2.6
Turns out I hadn't set permissions correctly. The directory is recognized once I let everyone execute from it. If there's a better way to do this, perhaps by moving python to a different location, let me know.
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?
[updated for 2021]
(Regardless if you are on Mac, Linux, or Windows:)
If you are confused about how to start the latest version of python, on most platforms it is the case that python3 leaves your python2 installation intact (due to the above compatibility reasons); thus you can start python3 with the python3 command.
Historically...
The naming convention is that generally, most scripts will call python2 or python3 explicitly. This happened due to a need for backwards compatibility.
Even though technically python doesn't even guarantee backwards compatibility between minor versions, Python3 really breaks backwards compatibility. At the time, programs invoking 'python' were expecting python2 (which was the main version at the time). Extremely old systems may have programs and scripts which expect python=python2, and changing this would break those programs and scripts.
At the time this answer was written, OP should not have changed this due to maintaining compatibility for old scripts.
Circa year 2021...
Nowadays, many years after the python2->python3 transition, most software explicitly refers to python2 or python3 (at least on Linux). For example, they might call #!/usr/bin/env python2 or #!/usr/bin/env python3. This has for example (python-is-python3-package) freed up the python command to be settable to a user default, but it really depends on the operating system.
The prescription for how distributions should handle the python command was written up in 2011 as PEP 394 -- The "python" Command on Unix-Like Systems. It was last updated in June 2019.
Basically if you are writing a library, you should specify the version of python (2 or 3, or finer-grained under specific circumstances) you can use. Otherwise as an end user, you should feel free to rename this for your own personal use (though your OS or distribution may not make that easy).
Shell alias:
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, and put it in your shell startup file. This will only work on your local computer (as it should), and is somewhat unnecessary compared to just typing it out (unless you invoke the command constantly).
Confused users should not try to create aliases or virtual environments or similar that make python execute python3; this is poor form.This is acceptable nowadays, but PEP 394 suggests encouraging users to use a virtualenv instead.
Different 3.* versions, or 2.* versions:
In the extremely unlikely case that if someone comes to this question with two python3 versions e.g. 3.1 vs 3.2, and you are confused that you have somehow installed two versions of python, this is possibly because you have done manual and/or manual installations. You can use your OS's standard package/program install/uninstall/management facilities to help track things down, and perhaps (unless you are doing dev work that surprisingly is impacted by the few backwards-incompatible changes between minor versions) delete the old version (or do make uninstall if you did a manual installation). If you require two versions, then reconfigure your $PATH variable so the 'default' version you want is in front; or if you are using most Linux distros, the command you are looking for is sudo update-alternatives. Make sure any programs you run which need access to the older versions may be properly invoked by their calling environment or shell (by setting up the var PATH in that environment).
A bit about $PATH
sidenote: To elaborate a bit on PATH: the usual ways that programs are selected is via the PATH (echo $PATH on Linux and Mac) environment variable. You can always run a program with the full path e.g. /usr/bin/🔳 some args, or cd /usr/bin then ./🔳 some args (replace blank with the 'echo' program I mentioned above for example), but otherwise typing 🔳 some args has no meaning without PATH env variable which declares the directories we implicitly may search-then-execute files from (if /usr/bin was not in PATH, then it would say 🔳: command not found). The first matching command in the first directory is the one which is executed (the which command on Linux and Mac will tell you which sub-path this is). Usually it is (e.g. on Linux, but similar on Mac) something like /usr/bin/python which is a symlink to other symlinks to the final version somewhere, e.g.:
% echo $PATH
/usr/sbin:/usr/local/bin:/usr/sbin:usr/local/bin:/usr/bin:/bin
% which python
/usr/bin/python
% which python2
/usr/bin/python2
% ls -l /usr/bin/python
lrwxrwxrwx 1 root root 7 Mar 4 2019 /usr/bin/python -> python2*
% ls -l /usr/bin/python2
lrwxrwxrwx 1 root root 9 Mar 4 2019 /usr/bin/python2 -> python2.7*
% ls -l /usr/bin/python2.7
-rwxr-xr-x 1 root root 3689352 Oct 10 2019 /usr/bin/python2.7*
% which python3
/usr/bin/python3
% ls -l /usr/bin/python3
lrwxrwxrwx 1 root root 9 Mar 26 2019 /usr/bin/python3 -> python3.7*
% ls -l /usr/bin/python3.7
-rwxr-xr-x 2 root root 4877888 Apr 2 2019 /usr/bin/python3.7*
% ls -l /usr/bin/python*
lrwxrwxrwx 1 root root 7 Mar 4 2019 /usr/bin/python -> python2*
lrwxrwxrwx 1 root root 9 Mar 4 2019 /usr/bin/python2 -> python2.7*
-rwxr-xr-x 1 root root 3689352 Oct 10 2019 /usr/bin/python2.7*
lrwxrwxrwx 1 root root 9 Mar 26 2019 /usr/bin/python3 -> python3.7*
-rwxr-xr-x 2 root root 4877888 Apr 2 2019 /usr/bin/python3.7*
lrwxrwxrwx 1 root root 33 Apr 2 2019 /usr/bin/python3.7-config -> x86_64-linux-gnu-python3.7-config*
-rwxr-xr-x 2 root root 4877888 Apr 2 2019 /usr/bin/python3.7m*
lrwxrwxrwx 1 root root 34 Apr 2 2019 /usr/bin/python3.7m-config -> x86_64-linux-gnu-python3.7m-config*
lrwxrwxrwx 1 root root 16 Mar 26 2019 /usr/bin/python3-config -> python3.7-config*
lrwxrwxrwx 1 root root 10 Mar 26 2019 /usr/bin/python3m -> python3.7m*
lrwxrwxrwx 1 root root 17 Mar 26 2019 /usr/bin/python3m-config -> python3.7m-config*
sidenote2: (In the rarer case a python program invokes a sub-program with the subprocess module, to specify which program to run, one can modify the paths of subprocesses with sys.path from the sys module or the PYTHONPATH environment variable set on the parent, or specifying the full path... but since the path is inherited by child processes this is not remotely likely an issue.)
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
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# -> 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# -> 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# -> 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# -> python3.2-32
lrwxr-xr-x 1 root admin 16 Apr 28 15:51 python3-config# -> 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# -> 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# -> pythonw3.2
lrwxr-xr-x 1 root admin 13 Apr 28 15:51 pythonw3-32# -> 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# -> idle2.7
-rwxrwxr-x 1 root admin 138 Jul 3 2010 idle2.7*
lrwxr-x--- 1 root admin 8 Nov 8 23:14 pydoc# -> pydoc2.7
-rwxrwxr-x 1 root admin 123 Jul 3 2010 pydoc2.7*
lrwxr-x--- 1 root admin 9 Nov 8 23:14 python# -> python2.7
lrwxr-x--- 1 root admin 16 Nov 8 23:14 python-config# -> 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# -> 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# -> smtpd2.7.py
-rwxrwxr-x 1 root admin 18272 Jul 3 2010 smtpd2.7.py*
Old question, but alternatively:
virtualenv --python=python3.5 .venv
source .venv/bin/activate
Update 11 May 2022 Wed EST PM 06:36
Thanks #Aditya Deshpande! Great suggestion!
I've just fixed my answer.
After taking ~/.bashrc or ~/.zshrc effect, there is no need to
quit and restart the terminal.
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 then checkout the version of Python
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!
Change the "default" Python by putting it ahead of the system Python on your path, for instance:
export PATH=/usr/local/bin:$PATH
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
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
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.
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.
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
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
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.
In short: change the path in Environment Variables!
For Windows:
Advanced System Settings > 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.
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
It should be noted that recent versions of Homebrew/MacOS will require a different entry for the PATH as the location where Homebrew installs Python has changed. Add this like to your .zshrc:
export PATH="/opt/homebrew/opt/python/libexec/bin:$PATH"
This will ensure that the appropriate unversioned python link installed by Homebrew appears before that of version 2.x and will protect you from being impacted by any version updates to python as brew will update the unversioned links whenever it updates the version.
Starting with macOS Catalina the default shell is zsh. Therefore, all those ~/.bash_profile changes are not going to change the default when you open a new terminal since the new terminal is a zsh shell and not a bash shell.
You can confirm your terminal is a zsh shell by typing echo $SHELL and you should see a response of: zsh.
What should you do? You should use a solution that works for zsh shell and bash shell. Therefore, do the following:
enter: vi ~/.bash_profile
enter: alias python='python3'
close and save your bash_profile. Enter: :wq
Now open/create your zsh profile. Enter: vi ~/.zshrc
source your bash inside your zshrc. Enter: source ~/.bash_profile
Now python will be aliased to python3 in your zsh shells (and in bash if you switch the default) automatically.
Test:
python --version
Python 3.8.9
In order to change the python version context switching without exporting environment variable. Please use the below video link to see:
https://youtu.be/jTN4MHNhJZs
After installing the newer version of python to your computer...
When you want to run a python program (e.g. 'program.py') from the terminal (using the latest version of python on your system); instead of running 'python program.py' run 'python3 program.py'
Similarly, if you want to use python in the terminal (using the latest version of python on your system) run 'python3' instead of 'python'
As a test try to run 'python3 --v' in the terminal...