I recently formatted my laptop and installed the Ubuntu operating system. I did not explicitly install Python. To check if it is pre-installed, I ran python --version in the terminal and got this:
$ python --version
Command 'python' not found, but can be installed with:
sudo apt install python3
sudo apt install python
sudo apt install python-minimal
You also have python3 installed, you can run 'python3' instead.
Then I checked python3 --version and got this: Python 3.6.9.
How is this possible? Should I install python as well? Or can I continue to use python3? Would this cause any problems?
Recent Ubuntu versions do not install python 2 by default, as python 2 is now "dead". However, the command python is not (yet) linked to python 3, to avoid some confusion; traditionally, python was for python 2 while python3 was for python 3.
In case you want to change this behavior and use python to run python 3, try installing a package named 'python-is-python3'. Then you can run python --version and see that it points to python 3.
In theory it might cause confusion for some legacy programs, but I haven't seen any issue so far for about a year.
In 20.04 LTS, the python included in the base system is Python 3.8. Python 2.7 has been moved to universe and is not included by default in any new installs.
Remaining packages in Ubuntu which require Python 2.7 have been updated to use /usr/bin/python2 as their interpreter, and /usr/bin/python is not present by default on any new installs. On systems upgraded from previous releases, /usr/bin/python will continue to point to python2 for compatibility. Users who require /usr/bin/python for compatibility on newly-installed systems are encouraged to install the python-is-python3 package, for a /usr/bin/python pointing to python3 instead.
— https://wiki.ubuntu.com/FocalFossa/ReleaseNotes
Just python on Linux traditionally refers to Python 2. python3 is the correct command if you want to use Python 3 (which you should, as Python 2 is EOL).
TL;DR: Just use python3
Python on Ubuntu refers to Python v2. If you were to run
python --version
you would see an output in the format of
Python 2.x.y
Python 2 has been sunset, which means it no longer will be updated and the recommendation is to move to Python3.
To run a program with Python 3, you just need to use python3 command instead.
python3 ./app.py
I am trying to update Python to 3.7.4 on my Mac. Currently when I type python3 --version, it shows that I have Python 3.7.3 I have tried to update using just the standalone installer from the website as well as homebrew but even through all of these methods, python3 --version still returns to me 3.7.3. Even when I try to upgrade with Brew, it says that 3.7.4 is installed...
Picture for reference:
Please help and thank you in advance!
Update: Check what python version you are using by running which python, at this point you might figure out what version of Python is being used to solve this problem. Otherwise, follow up this steps:
I would remove all Python installations and use Homebrew to install it.
First, run which python:
/Library/Frameworks/Python.framework/Versions/2.7/bin/python
Delete the entire Python.framework directory from /Library/Frameworks.
Second, run which python3:
/usr/local/bin/python3
Again, delete the entire python3 directory.
Now use brew doctor in order to see possible issues with symlinks. If you have issues run brew prune or brew cleanup --prune. This will remove all of the symlinks.
Reinstall python and python3 via homebrew:
brew install python
Some older apps may count on the Python2.7 framework being installed. It sounds like you may not have your bash $PATH set to look for homebrew binaries before the built-in ones. You can edit your ~/.profile file, and make sure that /usr/local/bin is the first entry by adding the following line to the end of .profile:
export PATH=/usr/local/bin:$PATH
ln -s -f /usr/local/bin/python /usr/local/bin/python
https://dev.to/malwarebo/how-to-set-python3-as-a-default-python-version-on-mac-4jjf
Just type in the below and it'll work
python3 --version
I used to have python and python3 installed. So I could decide which python to use. I now updated python with homebrew and it migrated python3 to python. How do I run python2 now?
When I check the installation I get:
$ python -V
Python 3.6.4
$ python2 -V
-bash: python2: command not found
$ python3 -V
Python 3.6.4
If I try to simply reinstall python2 I get:
$ brew install python2
Warning: python#2 2.7.14_1 is already installed
However I cannot use python2.
python2: command not found
You're missing the symbolic link that Homebrew makes from the Cellar to the actual bin directory on your path.
Use:
brew link python2
to fix that.
You may run into a warning:
Warning: python#2 is keg-only and must be linked with --force Note that doing so can interfere with building software.
See the accepted answer to this SO question for some details on that.
In most case, you can then safely use
brew link --force python2
if you're not planning building your own libraries that require the source code (libpython.so and Python.h) for Python 2.
If you do require the source code, you'll need to provide the include paths and library paths to e.g. /usr/local/Cellar/python/2.7.14_3/Frameworks/Python.framework/Versions/2.7/include/python2.7 and /usr/local/Cellar/python/2.7.14_3/Frameworks/Python.framework/Versions/2.7/lib/. But that's a different topic or question.
To use pip for Homebrew's Python 2, best to use is
python2 -m pip <command>
Then you can clearly see what Python your pip command goes with, and keep it apart from Python 3 (which would be python3 -m pip).
Note
If you have Homebrew problems, first cause of action is to run
brew doctor
The error messages are usually quite helpful to fix at some of the problems.
It seems that Homebrew has changed things again - as I had both python 2.7.x and 3.x.x installed through Homebrew for the same reasons. After the initial update, python2 would no longer work, but if you used python#2 you would get access as before.
Now however, they have seemed to partially revert some of these changes. Calling python now points to the keg-only 2.7.x homebrew installation instead of the 3.x.x installation. In addition, python#2 no longer works, but python2 no does. python3 still points to the 3.x.x installation as before.
[NOTE: I have not modified my ~/.bash_profile for any of these changes to occur.]
Having trouble making sure I'm actually using the latest versions of Python even though they are already installed via homebrew.
$ brew upgrade python3
Error: python3 3.6.2 already installed
but:
$ python3 --version
Python 3.6.0
same goes for python2:
$ brew upgrade python
Error: python2 2.7.13_1 already installed
$ python --version
Python 2.7.10`
❯ echo `which python`
If this doesn't print '/usr/local/bin/python' (where brew actually installs binaries), then there's something wrong with your $PATH (probably '/usr/local/bin' is not there or it's inserted after '/usr/bin', so the system default python is being run instead).
++ it seems that brew names its python2.7 as python2 by default, and not as python, so you may also need to create a python2->python link in /usr/local/bin directory.
Do you have separate environment variables set up for each?
I have found in the past that having multiple versions of python 2 for example, without all the environment variables, can get quite confusing!
You may find when typing python3, windows is only looking at python 3.0, unless you are in the python 3.6.2 directory.
First I modified my $PATH: sudo nano /etc/paths so that /Library/Frameworks/Python.framework/Versions/3.6/bin was not being invoked. I made sure my paths were in the right order so that python looked for /usr/local/bin/python3 and /usr/local/bin/python2 first to force the issue.
However, $ python3 --version still returned
Python 3.6.0, though brew says python3 3.6.2 already installed.
brew doctor to the rescue: homebrew recommended a couple things. python was incorrectly symlinked so I ran brew --overwrite python3. Finally, it diagnosed python coming from /Library/Frameworks/Python.framework/Versions/3.6/bin, so I sudo rm -rf /Library/Frameworks/Python.framework. Now python versions are correct.
Homebrew brew doctor warning about /Library/Frameworks/Python.framework, even with brew's Python installed
Thank you everyone for your help.
I try to switch to Homebrew (after using fink and macport) on Mac OS X 10.6.2. I have installed python 2.7 with
brew install python
The problem is that, contrary to Macport, it seems that there is no python_select utility, and my default mac python is always default
which python
give me
/usr/bin/python
and /usr/bin/python is not a symlink
How can I do to make python brew flavour to be my default python ?
As suggested by the homebrew installer itself, be sure to add this to your .bashrc or .zshrc:
export PATH="/usr/local/opt/python/libexec/bin:$PATH"
As you are using Homebrew the following command gives a better picture:
brew doctor
Output:
==> /usr/bin occurs before /usr/local/bin This means that system-provided programs will be used instead of those provided by
Homebrew. This is an issue if you eg. brew installed Python.
Consider editing your .bash_profile to put: /usr/local/bin ahead of
/usr/bin in your $PATH.
See: How to symlink python in Homebrew?
$ brew link --overwrite python
Linking /usr/local/Cellar/python/2.7.3... 28 symlinks created
$ which python
/usr/local/bin/python
Quick fix:
Open /etc/paths
Change the order of the lines (highest priority on top)
In my case /etc/paths looks like:
/usr/local/bin
/usr/local/sbin
/usr/bin
/bin
/usr/sbin
/sbin
If you want to know more about paths in OSX I found this article quite useful:
http://muttsnutts.github.com/blog/2011/09/12/manage-path-on-mac-os-x-lion/
I did "brew install python" for OSX High Sierra. The $PATH had /usr/local/bin before any other path but still which python was pointing to the system's python.
When I looked deeper I found that there is no python executable at /usr/local/bin. The executable is named python2. To fix this problem create a symbolic link python pointing to python2:
/usr/local/bin $: ln -s python2 python
For Apple Silicon machines, the path are slightly different. After running brew install python, you must ensure your ~/.zshrc uses the correct Homebrew paths:
# Homebrew
eval "$(/opt/homebrew/bin/brew shellenv)"
# Homebrew: Python
export PATH="/opt/homebrew/opt/python/libexec/bin:$PATH"
Results:
% which python
/opt/homebrew/opt/python/libexec/bin/python
% python --version
Python 3.9.9
% which pip
/opt/homebrew/opt/python/libexec/bin/pip
% pip -V
pip 21.3.1 from /opt/homebrew/lib/python3.9/site-packages/pip (python 3.9)
python formula now uses python3(v3.6.5 for now), brew will link the directory:
/usr/local/opt/python -> ../Cellar/python/3.6.5
it will also link the binary:
/usr/local/bin/python3 -> ../Cellar/python/3.6.5/bin/python3
If you still need to use python2.x, use:
brew install python#2
To use homebrew's python, just put its directory in PATH, for bash:
export PATH="/usr/local/opt/python/libexec/bin:$PATH"
for fish:
set -x PATH /usr/local/opt/python/libexec/bin $PATH
Note:
doing this will shadow the system default version of python
homebrew used to link python to /usr/local/share/python in older versions.
Homebrew does NOT replace stuff in "/usr/bin". You'll just want to put "/usr/local/bin" ahead of "/usr/bin" in your path, then "which python" will give you "/usr/local/bin/python".
Replacing /usr/bin/python (or /usr/bin/ruby) is highly unrecommended.
Modify your $PATH, Add this in your bashrc or bash_profile:
export PATH=/usr/local/bin:/usr/local/sbin:~/bin:$PATH
more click here:
Issue #89791
I did brew install python, my $PATH was good, but still, which python gave me the system installed one. Restarting the terminal fixed it.
You need to edit your PATH environmental variable to make sure wherever the homebrew python is located is searched before /usr/bin. You could also set things up in your shell config to have a variable like PYTHON be set to your desired version of python and call $PYTHON rather than python from the command line.
Also, as another poster stated (and especially on mac) DO NOT mess with the python in /usr/bin to point it to another python install. You're just asking for trouble if you do.
python now points to python3, if you need python 2 then do:
brew install python#2 and then in your .zshrc or .bashrc file
export PATH="/usr/local/opt/python#2/libexec/bin:$PATH"
Now, pyhon --version = Python 2.7.14 and python3 --version = Python 3.6.4.
That's the behavior I'm used to seeing in my terminal.
I believe there are means to make homebrew python default, but in my opinion the proper way to solve a problem is not to mess with system python paths: it is better to create a virtualenv in which homebrew python would be default (by using virtualenv --python option). Using tools like python_select is almost always a bad idea.
Use pyenv instead to install and switch between versions of Python. I've been using rbenv for years which does the same thing, but for Ruby. Before that it was hell managing versions.
Consult pyenv's github page for installation instructions. Basically it goes like this:
- Install pyenv using homebrew. brew install pyenv
- Add a function to the end of your shell startup script so pyenv can do it's magic. echo -e 'if command -v pyenv 1>/dev/null 2>&1; then\n eval "$(pyenv init -)"\nfi' >> ~/.bash_profile
Use pyenv to install however many different versions of Python you need. pyenv install 3.7.7.
Set the default (global) version to a modern version you just installed. pyenv global 3.7.7.
If you work on a project that needs to use a different version of python, look into pyevn local. This creates a file in your project's folder that specifies the python version. Pyenv will look override the global python version with the version in that file.
Add the /usr/local/opt/python/libexec/bin explicitly to your .bash_profile:
export PATH="/usr/local/opt/python/libexec/bin:$PATH"
After that, it should work correctly.
Just do:
brew install python
brew link python
After doing that, add this to your bashrc or bash_profile:
alias python='/usr/local/bin/python2'
Enjoy!
You can edit /etc/paths. Here is mine:
/usr/local/bin
/usr/bin
/bin
/usr/sbin
/sbin
Then add a symlink for the python version. In my case
$ cd /usr/local/bin
$ ln -s python3 python
Voila!
If you are fish shell
echo 'set -g fish_user_paths "/usr/local/opt/python/libexec/bin" $fish_user_paths' >> ~/.config/fish/config.fish
try this
which python3
Try typing python3 instead of just python
Greeting folks! I have the need to use python 3.10 version to harness its new features. My solved solution at 2022-07-03 is as follows. Have fun coding python!
» rm '/usr/local/bin/pip3.10'
» brew link python#3.10
» echo 'export PATH="/usr/local/opt/python#3.10/bin:$PATH"' >> ~/.zshrc
» python3
Python 3.10.5 (main, Jun 23 2022, 17:15:25) [Clang 13.1.6 (clang-1316.0.21.2.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
Since High Sierra, you need to use:
sudo chown -R $(whoami) $(brew --prefix)/*
This is because /usr/local can no longer be chowned
brew link python
And you must create/add an alias for python and put it in your .zprofile (Located in Users/username folder, if you press Shift+command+.
This must point to your homebrew python installation location.
alias python ='opt/homebrew/bin/python3'
No idea what you mean with default Python. I consider it bad practice to replace the system Python interpreter with a different version. System functionality may depend in some way on the system Python and specific modules or a specific Python version. Instead install your custom Python installations in a safe different place and adjust your $PATH as needed in order to call you Python through a path lookup instead of looking for the default Python.