I've just installed Python version 3.11 (I also moved versions 3.8 and 3.9 to the trash from my Applications folder).
I can see it in the following:
$ myname#name-MBP miniconda3 % ls /usr/local/bin/py*
/usr/local/bin/pydoc3 /usr/local/bin/python3-intel64
/usr/local/bin/pydoc3.11 /usr/local/bin/python3.11
/usr/local/bin/python3 /usr/local/bin/python3.11-config
/usr/local/bin/python3-config /usr/local/bin/python3.11-intel64
(Any additional recommendations on whether I need to clean things up would be much appreciated.)
Checking python3 --version still displays Python 3.8.13.
First attempt to solve
Initially I tried installing it from the command line using homebrew and specifying the version:
brew install python#3.11
I also tried using conda, but neither of these worked.
Second attempt to solve
My initial thought was to check my PATH (I think this is how Python decides which version to use, but please correct me if I'm wrong).
This still only contained version 8 paths:
/Users/myname/miniconda3/lib/python38.zip
/Users/myname/miniconda3/lib/python3.8
/Users/myname/miniconda3/lib/python3.8/lib-dynload
/Users/myname/.local/lib/python3.8/site-packages
/Users/myname/miniconda3/lib/python3.8/site-packages
So I added the Python3.11 path to it using
PYTHONPATH="/usr/local/bin/pydoc3.11/:$PYTHONPATH"
export PYTHONPATH
Now it includes the v3.11 path when I print out sys.path:
/usr/local/bin/python3.11
/usr/local/bin/pydoc3.11
/Users/myname/miniconda3
/Users/myname/miniconda3/lib/python38.zip
/Users/myname/miniconda3/lib/python3.8
/Users/myname/miniconda3/lib/python3.8/lib-dynload
/Users/myname/.local/lib/python3.8/site-packages
/Users/myname/miniconda3/lib/python3.8/site-packages
But the python3 --version output is still unchanged.
Questions
I'm nervous to keep playing around with the contents of my path and entering random command line executions to try to solve this because I really have no clue what I'm doing.
What's happening here?
How can I get the output of python3 --version to be 3.11?
So first thing to understand is setting the variable PYTHONPATH will not affect which version of python is executed by the shell. The shell (bash/zsh) only knows to scan the paths in the PATH env var to figure out all the executables.
Now there are two ways to solve this.
1. Using the python#3.11 from homebrew.
There are several downsides to using this method. Currently, the default python3 by brew is 3.10.x. Whenever you will install any cask or formula that depends on python#3, it'll invariably install the python#3 formula aka 3.10.x. Installing python3 will make brew symlink 3.10.x into /opt/homebrew/bin.
Python 3.11.x can be used by installing python#3.11 and invoking python3.11. This should drop you into the Python 3.11 interpreter. Append all python executable names with the version like pip will be pip3.11
Trying to force 3.11 over 3.10 links will be complicated and cause instability. It'll only cause frustration during development.
2. Using VirtualEnvs
Your best bet for the most stable and no-headache approach to python is to create virtual envs using either venv or pyenv. use pyenv-virtualenv for max ease of use.
One limitation of venv is that it'll create a virtualenv of the same version that invoked it. Aka if you do brew install python#3 && python3 -m venv <folder>, it'll create virtualenv of python3. For 3.11 you'll have to brew install python#3.11 && python3.11 -m venv <folder>. Pyenv on the other hand can install any version of python.
Go through https://www.dataquest.io/blog/a-complete-guide-to-python-virtual-environments/ and https://github.com/pyenv/pyenv-virtualenv to understand and learn more.
I always used Anaconda on Windows so far and could set up an environment while choosing which exact Python to use. E.g. conda create -n myEnvName python=3.7
Now, I want to familiarize with Ubuntu 18.04 LTS and use basic Python environments.
So I followed these steps:
Created folder in my home = ~/.venvPython
(a) I think I already had a 2.7 and 3.6 by default on the OS.
(b) I do not remember for sure, I think I had to do this sudo apt-get install python3-venv.
Created environment this way after CD'ing to .venvPython folder ran this: python3 -m venv venv1BigDataPgm2
source ~/.venvPython/venv1BigDataPgm2/bin/activate
Command python --version says: Python 3.6.9
Running whereis Python shows this:
rohit#rohitUb18043LTS:~$ whereis python
python: /usr/bin/python3.6 /usr/bin/python3.6-config /usr/bin/python2.7-config /usr/bin/python3.6m-config /usr/bin/python /usr/bin/python3.6m /usr/bin/python2.7 /usr/lib/python3.8 /usr/lib/python3.7 /usr/lib/python3.6 /usr/lib/python2.7 /etc/python3.6 /etc/python /etc/python2.7 /usr/local/lib/python3.6 /usr/local/lib/python2.7 /usr/include/python3.6 /usr/include/python3.6m /usr/include/python2.7 /usr/share/python /usr/share/man/man1/python.1.gz
My doubts:
Can I specify a Python version directly while creating the environment like with conda?
How do I change this to some other interpreter instead of the 3.6.9?
Do I have to manually install a different Python first, then point it somehow?
Please guide me. Thank you.
Rohit
As far as I can tell the venv standard library appeared in Python 3.3 and was never backported to 2.7.
venv can only create virtual environment for its own version of the interpreter and the virtual environment directory can not be moved to a different location or be renamed. Python 3.foo can not create a virtual environment for Python 3.bar. So it is best to pick the wanted interpreter right from the start.
Since, as shown by the output of whereis python, you seem to already have multiple Python interpreters already installed, you should be able to do something like the following:
$ /path/to/python3.3 -m venv /path/to/my/venvs/venv33
$ /path/to/python3.8 -m venv /path/to/my/venvs/venv38
There seems to be a way to change the Python interpreter associated with a virtual environment (I have not tested it, not sure what the limitations are):
$ /path/to/python3.8 -m venv --upgrade /path/to/my/venvs/venv33
Alternatively use virtualenv which seems to offer a bit more flexibility, but is probably less efficient (its next major release, virtualenv 20, should bring a lot of improvements though).
Ubuntu and other Debian-based systems generally ship whichever Python version was current and deemed sufficiently tested when the release was published; after that, only security updates which preserve the version number but add patches are released (so you might get 3.6.9-123security4 instead of 3.6.9-5 or whatever was current when the release was cut).
If you want to run a specific Python version on one of these platforms, see if you can find an Apt source which provides this version for your system (Ubuntu has a soft underbelly of unofficial PPAs of various repute; Debian has backports) or install it from source yourself. There are add-ons like pyenv which let you do this rather easily, safely, and transparently.
There may also be an existing package which gives you a particular newer version; for example, you can do apt install python3.7 and apt install python3.8 on Ubuntu 18.04, but there are no packages for 3.5 or 3.9. Try apt policy python3.7 to see which specific minor version is available from the Ubuntu package archive.
An alternative to that is to always specify the python version you wish use when running a script.
python3.6 test_script.py
Usually, when I'm on Linux and don't need a specific python3 version, I create native python3 environments.
python3 -m venv myenv
source myenv/bin/activate
But if I need a specific python3 version, I do:
python3.9 -m venv myenv
source myenv/bin/activate
To use a specific python3 version with native environments, you have to install that version using the native package manager (eg. apt).
I have Python 3.7 installed on my computer. I want to use tensorflow and just found out that it basically doesn't support 3.7, so I'd like to (also) install Python 3.6.
Any suggestions of how to do that? Do I have to uninstall 3.7 and replace it by 3.6 or is there a way to just use 3.6 for the stuff related to tensorflow?
One of the recommended ways to have multiple python installations with differing libraries installed is to use Virtualenv. This gives you the possibility to have a specific python environment with it's own set of dependencies for each project you work on. This works not only for the dependencies, but also for different versions of python.
On top of that you can use Pipenv to manage the different virtualenvs. In a Pipfile you can describe your required python and it's dependencies which is used by Pipenv to manage a python env specific for your project.
I found this to work after searching for a while. Here are the steps I followed to install an older python version alongside my standard one:
Download the Python3.6 tgz file from the official website (eg. Python-3.6.6.tgz)
Unpack it with tar -xvzf Python-3.6.6.tgz
cd Python-3.6.6
run ./configure
run make altinstall to install it (install vs altinstall explanation here Difference in details between "make install" and "make altinstall")
You'll normally find your new python install under /usr/local/bin. Now you can create a new virtualenv specifying the python version to use with:
virtualenv --python=python3.6 env3.6
Get into the virtualenv running the command source env3.6/bin/activate.
Install tensorflow with the classic pip3 install tensorflow
Profit
Yesterday i reinstalled my Linux Mint duo similar issue I am facing right now.
I installed Python 3.6 with:
apt-get install build-essential checkinstall libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev
cd /usr/src
wget https://www.python.org/ftp/python/3.6.0/Python-3.6.0.tgz
tar xzf Python-3.6.0.tgz
cd Python-3.6.0
./configure
make altinstall
python3.6 -V
And then, there is Python 2.7.12 on Linux as default, which i can see by:
python -V
Python 2.7.12
When i check:
python3 -V
My output is:
Python 3.5.2
However:
python3.6 -V
Python 3.6.0
I also downloaded and installed Pycharm but the problem is, Project Interpreter can't find Python 3.6, i also can't add Python 3.6 manually in any way.
I've noticed that other Python versions PATHs in PyCharm looks like:
/usr/bin/python2.7
/usr/bin/python3.5
But i can't find any Python 3.6 in there.
One more thing - When i checked:
/usr/local/lib/python3.5/dist-packages
It's the only folder i can find there, it was empty but when i tried to do something with pip, it automatically saved there.
However:
/usr/local/lib/python3.6
does not contain such a folder. As i remember, it was the folder where all modules were installed.
1) Is Python 3.6 installed correctly, if not, how to fix that?
2) How the hell Python 3.5.2 has been installed there and should i delete it?
3) How to make PyCharm working on Python 3.6
4) Python 3.5 will cause problems with installing modules, I had same issue before reinstall of my Linux. What's wrong here?
What is the output of the command:
$ update-alternatives --list python3
on your system?
Does it look like:
/usr/bin/python3.5
/usr/bin/python3.6
If so you can use the command:
$ sudo update-alternatives --config python3
to choose which python3 version to run. However, be warned, some of your installed software may depend on version 3.5 and changing the default python3 could have side effects. You should be able to update to python3.6 for your default and then install the packages you need, switching back to 3.5 as the default when you want to.
However, you will constantly be swapping your defaults, and sooner or later you will probably forget and get into some kind of versioning conflict.
Depending on your specific needs for python3.6, you can use it selectively only when you need it.
Here are some examples...
1) When working at the command line, start your python session with 'python3.6' instead of 'python3' and you will be using 3.6 instead of 3.5.
2) When writing python executables, use the shebang line '#! /usr/bin/python3.6' instead of '#! /usr/bin/python3' to ensure you are using python 3.6
3) when running a python file at the command line use
'python3.6 file_name.py'
or
'python3.5 file_name.py'
as needed to call the specific version of python you need.
These are all cumbersome, but relatively safe. You will only be using 3.6 when you need it.
The best way to keep your system safe, support multiple versions of python, and not break any system dependencies on the 3.5 release, is to learn about virtual environments. These are environments that use their own specified version of python, and the specific packages for their environment.
Virtual environments are a little complicated at first, but once you get the hang of them it is nice to have a few separate projects, each with slightly different sets of dependencies, all in their own footprints and not stepping on each other.
Here are some tutorials:
http://docs.python-guide.org/en/latest/dev/virtualenvs/
https://realpython.com/python-virtual-environments-a-primer/
https://docs.python.org/3/tutorial/venv.html
There are plenty of tutorials on youtube as well.
Good luck and happy coding!
I've installed virtualenv via pip and get this error after creating a new environment:
selenium:~ auser$ virtualenv new
New python executable in new/bin/python
ERROR: The executable new/bin/python is not functioning
ERROR: It thinks sys.prefix is u'/System/Library/Frameworks/Python.framework/ Versions/2.6' (should be '/Users/user/new')
ERROR: virtualenv is not compatible with this system or executable
In my environment:
PYTHONPATH=/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages
PATH=/System/Library/Frameworks/Python.framework/Versions/2.6/bin:/Library/Frameworks/Python.framework/Versions/2.6/bin:/Library/Frameworks/Python.framework/Versions/2.6/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin
How can I repair this?
Thanks.
Just in case there's someone still seeking for the answer.
I ran into this same problem just today and realized since I already have Anaconda installed, I should not have used pip install virtualenv to install virtual environment as this would give me the error message when trying to initiate it later. Instead, I tried conda install virtualenv then entered virtualenv env_mysite and problem solved.
Like #RyanWilcox mentioned, you might be inadvertently pointing virtualenv to the wrong Python installation. Virtualenv comes with a -p flag to let you specify which interpreter to use.
In my case,
virtualenv test_env
threw the same error as yours, while
virtualenv -p python test_env
worked perfectly.
If you call virtualenv -h, the documentation for the -p flag will tell you which python it thinks it should be using; if it looks wonky, try passing -p python. For reference, I'm on virtualenv 1.11.6.
In case anyone in the future runs into this problem - this is caused by your default Python distribution being conda. Conda has it's own virtual env set up process but if you have the conda distribution of python and still wish to use virtualenv here's how:
Find the other python distribution on your machine: ls -ls /usr/bin/python*
Take note of the availble python version that is not conda and run the code below (note for python 3 and above you have to upgrade virtualenv first): virtualenv -p python2.7(or your python version) flaskapp
I've run across this problem myself. I wrote down the instructions in a README, which I have pasted below....
I have found there are two things that work:
Make sure you're running the latest virtualenv (1.5.1, of this writting)
If you're using a non system Python as your standard Python (which python to check) Forcefully use the System supplied one.
Instead of virtualenv thing use /usr/bin/python2.6 PATH/TO/VIRTUALENV thing (or whatever which
python returned to you - this is what it did for me when I ran into this issue)
I had the same problem and as I see it now, it was caused by a messy Python installation. I have OS X installed for over a year since I bought a new laptop and I have already installed and reinstalled Python for several times using different sources (official binaries, homebrew, official binaries + hand-made adjustments as described here). Don't ask me why I did that, I'm just a miserable newbie believing everything will fix itself after being re-installed.
So, I had a number of different Pythons installed here and there as well as many hardlinks pointing at them inconsistently. Eventually I got sick of all of them and reinstalled OS X carefully cleaned the system from all the Pythons I found using find utility. Also, I have unlinked all the links pointing to whatever Python from everywhere. Then I've installed a fresh Python using homebrew, installed virtualenv and everything works as a charm now.
So, my recipe is:
sudo find / -iname "python*" > python.log
Then analyze this file, remove and unlink everything related to the version of Python you need, reinstall it (I did it with homebrew, maybe official installation will also work) and enjoy. Make sure you unlink everything python-related from /usr/bin and /usr/local/bin as well as remove all the instances of Frameworks/Python.framework/Versions/<Your.Version> in /Library and /System/Library.
It may be a dirty hack, but it worked for me. I prefer not to keep any system-wide Python libraries except pip and virtualenv and create virtual environments for all of my projects, so I do not care about removing the important libraries. If you don't want to remove everything, still try to understand whether your Pythons are, what links point to them and from where. Then think what may cause the problem and fix it.
I ran into a variation of this "not functioning" error.
I was trying to create an environment in a folder that included the path ".../Programming/Developing..." which is actually "/Users/eric/Documents/Programming:Developing/"
and got this error:
ImportError: No module named site
ERROR: The executable env/bin/python2.7 is not functioning
ERROR: It thinks sys.prefix is u'/Users/eric/Documents/Programming:Developing/heroku' (should be u'/Users/eric/Documents/Programming:Developing/heroku/env')
ERROR: virtualenv is not compatible with this system or executable
I tried the same in a different folder and it worked fine, no errors and env/bin has what I expect (activate, etc.).
I got the same problem and I found that it happens when you do not specify the python executable name properly. So for python 2x, for example:
virtualenv --system-site-packages -p python mysite
But for python 3.6 you need to specify the executable name like python3.6
virtualenv --system-site-packages -p python3.6 mysite
On on OSX 10.6.8 leopard, after having "upgraded" to Lion, then downgrading again (ouch - AVOID!), I went through the Wolf Paulus method a few months ago, completely ignorant of python. Deleted python 2.7 altogether and "replaced" it with 3.something. My FTP program stopped working (Fetch) and who knows what else relies on Python 2.7. So at that point I downloaded the latest version of 2.7 from python.org and it's installer got me up and running - until i tried to use virtualenv.
What seems to have worked for me this time was totally deleting Python 2.7 with this code:
sudo rm -R /System/Library/Frameworks/Python.framework/Versions/2.7
removing all the links with this code:
sudo rm /usr/bin/pydoc
sudo rm /usr/bin/python
sudo rm /usr/bin/pythonw
sudo rm /usr/bin/python-config
I had tried to install python with homebrew, but apparently it will not work unless all of XTools is installed, which I have been avoiding, since the version of XTools compatible with 10.6 is ancient and 4GB and mostly all I need is GCC, the compiler, which you can get here.
So I just installed with the latest download from python.org.
Then had to reinstall easy_install, pip, virtualenv.
Definitely wondering when it will be time for a new laptop, but there's a lot to be said for buying fewer pieces of hardware (slave labor, unethical mining, etc).
The above solutions failed for me, but the following worked:
python3 -m venv --without-pip <ENVIRONMENT_NAME>
. <ENVIRONMENT_NAME>/bin/activate
curl https://bootstrap.pypa.io/get-pip.py | python
deactivate
It's hacky, but yes, the core problem really did just seem to be pip.
I did the following steps to get virtualenv working :
Update virtualenv as follows :
==> sudo pip install --upgrade virtualenv
Initialize python3 virtualenv :
==> virtualenv -p python3 venv
I had this same issue, and I can confirm that the problem was with an outdated virtualenv.py file.
It was not necessary to do a whole install --upgrade.
Replacing the virtualenv.py file with the most recent version sufficed.
I also had this problem, and I tried the following method which worked for me:
conda install virtualenv
virtualenv --system-site-packages /anaconda/envs/tensorflow (here envs keeps all the virtual environments made by user)
source /anaconda/envs/tensorflow/bin/activate
Hope it's helpful.
I had this same issue when trying to install py2.7 on a newer system. The root issue was that virtualenv was part of py3.7 and thus was not compatible:
$ virtualenv -p python2.7 env
Running virtualenv with interpreter /usr/local/bin/python2.7
New python executable in /Users/blah/env/bin/python
ERROR: The executable /Users/blah/env/bin/python is not functioning
ERROR: It thinks sys.prefix is u'/Library/Frameworks/Python.framework/Versions/2.7' (should be u'/Users/blah/env')
ERROR: virtualenv is not compatible with this system or executable
$ which virtualenv
/Library/Frameworks/Python.framework/Versions/3.7/bin/virtualenv
# install proper version of virtualenv
$ pip2.7 install virtualenv
$ /Library/Frameworks/Python.framework/Versions/2.7/bin/virtualenv -p python2.7 env
$ . ./env/bin/activate
(env) $
Open terminal and type /Library/Frameworks/Python.framework/Versions/
then type ls /Library/Frameworks/Python.framework/Versions/2.7/bin/
if you are using Python2(or any other else).
Edit ~/.bash_profile and add the following line:
export PATH=$PATH:/Library/Frameworks/Python.framework/Versions/2.7/bin/
cat ~/.bash_profile
In my case the content of ~/.bash_profile is as follows:
export PATH=$PATH:/Library/Frameworks/Python.framework/Versions/2.7/bin/
Now the virtualenv command should work.
If you continue to have trouble with virtualenv, you might try pythonbrew, instead. It's an alternate solution to the same problem. It works more like Ruby's rvm: It builds and creates an entire instance of Python, under $HOME/.pythonbrew, and then sets up some bash functions that allow you to switch easily between versions. Where virtualenv shadows the system version of Python, using symbolic links as part of its solution, pythonbrew builds entirely self-contained installations of Python.
I used virtualenv for years. It's a decent solution, but I've switched to pythonbrew lately. Having completely self-contained Python instances means that installing a new one takes awhile (since pythonbrew actually compiles Python from scratch), but the self-contained nature of each installation appeals to me. And disk is cheap.