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)
I get this error when I'm running Python 3.6 Jupyter notebooks in the console.
OMP: Error #15: Initializing libiomp5.dylib, but found libomp.dylib already initialized.
OMP: Hint This means that multiple copies of the OpenMP runtime have been linked into the program. That is dangerous, since it can degrade performance or cause incorrect results. The best thing to do is to ensure that only a single OpenMP runtime is linked into the process, e.g. by avoiding static linking of the OpenMP runtime in any library. As an unsafe, unsupported, undocumented workaround you can set the environment variable KMP_DUPLICATE_LIB_OK=TRUE to allow the program to continue to execute, but that may cause crashes or silently produce incorrect results. For more information, please see http://www.intel.com/software/products/support/.
I have a few different versions of ligomp:
(µ_env) jespinozlt-osx:lib jespinoz$ pwd
/Users/jespinoz/anaconda/envs/µ_env/lib
(µ_env) jespinozlt-osx:lib jespinoz$ ls -lhtr | grep "omp"
-rw-rw-r-- 4 jespinoz tigr 165B Oct 28 2016 libgomp.spec
-rw-rw-r-- 4 jespinoz tigr 108K Oct 28 2016 libgomp.a
-rwxrwxr-x 11 jespinoz tigr 62K Oct 28 2016 libgomp.1.dylib
-rwxrwxr-x 6 jespinoz tigr 489K Oct 27 17:30 libomp.dylib
-rwxrwxr-x 5 jespinoz tigr 176K Mar 14 13:10 libiompstubs5.dylib
-rwxrwxr-x 5 jespinoz tigr 296K Mar 14 13:10 libiomp5_db.dylib
-rwxrwxr-x 5 jespinoz tigr 2.7M Mar 14 13:10 libiomp5.dylib
lrwxr-xr-x 1 jespinoz tigr 15B Apr 10 14:51 libgomp.dylib -> libgomp.1.dylib
A quick patch is this:
import os
os.environ['KMP_DUPLICATE_LIB_OK']='True'
How can I properly fix this? Do I need to delete my entire conda and start over?
I had this problem and tried a number of solutions described at https://github.com/dmlc/xgboost/issues/1715.
The posting by Alex Evers (1ps0 commented on Feb 16 (2029)) worked for me.
brew uninstall libiomp clamp-omp
conda uninstall intel-openmp -n base
conda install -c intel openmp -n myenv
conda install nomkl -n myenv
I found a solution from the same source https://github.com/dmlc/xgboost/issues/1715
This seems to be a problem specific to macOS.
What worked for me is adding the following lines of code in the beginning.
import os
os.environ['KMP_DUPLICATE_LIB_OK']='True'
PS.
I experienced this while running Keras neural net.
I have python2.7 and python3.6 in my Ubuntu, both installed from apt-get.
I found python2.7 is only 3.4M, but python3.6 approximates 12M, why so big difference?
The following is the command:
bash-4.3$ ls -lh `which python2.7`
-rwxr-xr-x 1 root root 3.4M Nov 13 03:46 /usr/bin/python2.7
bash-4.3$ ls -lh `which python3.6`
-rwxr-xr-x 2 root root 18K May 5 2018 /usr/local/bin/python3.6
Seems python3.6 executable uses dynamic linking, so I used pamp to find that .so file :
00007fdf14242000 2668 r-x-- 0000000000000000 008:00001 libpython3.6m.so.1.0
00007fdf144dd000 2044 ----- 000000000029b000 008:00001 libpython3.6m.so.1.0
00007fdf146dc000 12 r---- 000000000029a000 008:00001 libpython3.6m.so.1.0
00007fdf146df000 408 rw--- 000000000029d000 008:00001 libpython3.6m.so.1.0
It's libpython3.6m.so.1.0, then I checked its file size:
bash-4.3$ ls -lh /usr/local/lib/libpython3.6m.so.1.0
-r-xr-xr-x 1 root root 12M May 5 2018 /usr/local/lib/libpython3.6m.so.1.0
12M, why so large?
And I'm also confused that libpython3.6m.so.1.0 only occupies (2668k+2044k=)4.7M in virtual address space, where has the other 7.3M gone?
Thank you.
PS: I also used pmap to check the address space of python2.7, no dynamic library of python found, so I think python2.7 is statically linked.
I can't run my python programs in pycharm. I installed python3, pycharm and anaconda. I can open the project and write python code, but can't run the program in pycharm. I can use the terminal to run my program and it works fine. Any ideas how to use the right interpreter? Where can I find it? BTW I work with a mac.
When I try to add an interpreter I can add an Virtualenv Environment, Conda Environment or System Interpreter. When I click on System interpreter and choose one, it wont work. I tried to find my python version with the terminal and use it in pycharm, but it wont do anything.
Thats what I see:
entire screen
The icon also seems weird (red cross):
weird icon
Greetings, Stefan
Inspect your conda python installation via:
$ conda info
Mine is: /root/miniconda, so basic grepping shows what pythons do I have:
root#d03107c14a07:/notebook# ls -al /root/miniconda/bin/ | grep python
-rwxrwxr-x 1 root root 129 Apr 16 16:20 ipython
-rwxrwxr-x 1 root root 129 Apr 16 16:20 ipython2
lrwxrwxrwx 1 root root 9 Apr 16 16:20 python -> python2.7
-rwxrwxr-x 1 root root 1689 Apr 16 16:20 python-config
lrwxrwxrwx 1 root root 9 Apr 16 16:20 python2 -> python2.7
-rwxrwxr-x 1 root root 10302 Dec 21 2016 python2.7
And running it like below shows it works:
root#d03107c14a07:/notebook# /root/miniconda/bin/python
Python 2.7.13 |Anaconda 4.4.0 (64-bit)| (default, Dec 20 2016, 23:09:15)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
Anaconda is brought to you by Continuum Analytics.
Please check out: http://continuum.io/thanks and https://anaconda.org
>>>
We have the path, for me it's: /root/miniconda/bin/python
So, as we have it localized, we need to set it up with our Pycharm.
Go to Settings/Preferences and into Project interpreter, choose a settings wheel and Add - On the left you've got three options, choose Conda, your env might be found automatically, but if it isn't then you have the path to paste ;)
Official docs ref
conda info ref
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...