I am using 18.04 Ubuntu with Anaconda.Recently i have trying to install OpenCV through conda-forge channel in the base environment. I did not install purposely any Python version and did not use any pip command either in base environment. Now, in the base environment, if execute just python, i get the same python version as system version and if execute python3 , i get the version installed by conda-forge. Please refer the screen shot. Python_on_Conda_base
I would like to know what is difference between python and python3 command?.What is should i keep in mind? basically i prefer the version 3.7.5 Python
.So, only the Python3 has uses different version. So, question what i should take note when i using python3 some_script.py? what is pros and cons of having this 2 version?
So far,i did not face any issues, but removed the conda-forge channel from Anaconda to avoid any conflicts. Any thoughts?
After posting this question, i have noticed python --version command gives Python 3.7.5 on Conda base environment and Ubuntu terminal (outside Conda)
You most likely have set an alias for python to point to the python3 binary.
Check this by typing type python, which will probably give you
python is aliased to ...
The crux here is that an alias will not be detected by which and as you revealed in the comments your which python returns the correct python version from your conda base environment, which makes an alias the most likely explanation, as PATH issues can be ruled out.
If above command does indeed reveal an alias, then check you .bashrc or similar file that you might have modified for a line alias python=.... Delete it, restart your terminal and everything should work normally
I try to learn how to create a Python library. But I have a problem with activating a virtual environment. To be more specific: I was told to do this:
code from Realpython: virtual environment
.. I opened my console:
and paste the mentioned code:
$ python -m venv env && source ./env/bin/activate
$ python -m pip install -U pip wheel setuptools
Successfully installed pip 20.1 setuptools-46.1.3 wheel-0.34.2
But It was rejected (and I couldn't find on the internet why is that - probably the solution is simple, but I don't even know how to post a proper question to find it):
I tried to pate this code without dollar sing but it won't work too, also replacing $ with ! won't work.
I don't know why it doesn't work and what version of this code should I use.
can you help me?
Don't use windows :) go to linux. $ is special linux terminal symbol. The source is linux command too. guide. Use windows commands if you use windows. But the better way is going to linux.
Here is what I get when I run the following commands in my terminal:
python --version
python 2.7.1
python3 --version
python 3.7.3
I ran the 'Update Shell Profile.command' file that comes with the Python3 download, but it still doesn't change the value of
python version
when I run it. My question is, is this normal? Does it change anything important other than needing to type 'python3 file.py' to run 'file.py'? If so, how do I change this? (Also, the computer I am using uses Homebrew which I am not familiar with, I am not sure if this changes anything or how.)
Python 2.7 and Python 3.7 are the latest releases of python 2 and 3 repsectively. Those two are two different version which can co-exist together. You can have both versions installed in your computer at the same time. If u dont like that just uninstall one(I'd suggest python2). The main difference is that python 3 offers many advantages compared to python 2. Some of them would be that some libraries work only for that version other legacy ones work for the other version etc. So there is no problem with having both but like i said there is really no point. Just choose whch version u like and uninstall the other one.
I am using Python 3.5.2 version on Windows 7 and tried using python3 app.py. I am getting this error message:
'python3' is not recognized as an internal or external command,
operable program or batch file.
Is there any specific cause about why the python3 command is not working?
I also verified that the PATH is added to environment variables.
There is no python3.exe file, that is why it fails.
Try:
py
instead.
py is just a launcher for python.exe. If you have more than one python versions installed on your machine (2.x, 3.x) you can specify what version of python to launch by
py -2 or
py -3
You can also try this:
Go to the path where Python is installed in your system. For me it was something like C:\Users\\Local Settings\Application Data\Programs\Python\Python37
In this folder, you'll find a python executable. Just create a duplicate and rename it to python3. Works every time.
Python3.exe is not defined in windows
Specify the path for required version of python when you need to used it by creating virtual environment for your project
Python 3
virtualenv --python=C:\PATH_TO_PYTHON\python.exe environment
Python2
virtualenv --python=C:\PATH_TO_PYTHON\python.exe environment
then activate the environment using
.\environment\Scripts\activate.ps1
Yes, I think for Windows users you need to change all the python3 calls to python to solve your original error. This change will run the Python version set in your current environment. If you need to keep this call as it is (aka python3) because you are working in cross-platform or for any other reason, then a work around is to create a soft link. To create it, go to the folder that contains the Python executable and create the link. For example, this worked in my case in Windows 10 using mklink:
cd C:\Python3
mklink python3.exe python.exe
Use a (soft) symbolic link in Linux:
cd /usr/bin/python3
ln -s python.exe python3.exe
In my case I have a git hook on commit, specified by admin. So it was not very convenient for me to change the script (with python3 calls).
And the simplest workaround was just to copy python.exe to python3.exe.
Now I could launch both python and python3.
If python2 is not installed on your computer, you can try with just python instead of python3
For Python 27
virtualenv -p C:\Python27\python.exe django_concurrent_env
For Pyton36
virtualenv -p C:\Python36\python.exe django_concurrent_env
Enter the command to start up the server in that directory:
py -3.7 -m http.server
I had a related issue after installing windows 11, where python3 in cmd would open the windows store. I was able to sort it out between this post and this other one. In short, I reinstalled python and made sure to add it to PATH. Then, in settings, Apps > Apps & Features > App Execution aliases. Here, all I had to do was make sure that every single python .exe (including idle and pip) were turned off EXCEPT FOR the python3.exe alias. Now it works like a charm.
FWIW:
The root of this issue is not with you or with python. Apparently, Microsoft wanted to make installing python easier for young kiddos getting interested in coding, so they automatically add an executable to PATH. For those of us that already have this executable, it can cause these issues.
Found out instead press the play button the top right and it should work in visual studios:
Do not disable according to first answer
Saying python3 in the command will not work by default.
After figuring out the problem with the modules (Solution): https://youtu.be/paRXeLurjE4
Summary:
To import python modules in case of problem to import modules:
Hover over python in search:
Click open in folder
Hover over and right click
click properties
copy everything in path before \python.exe
close those windows
For cmd (administrator):
cd --path that was copied--
then python -m pip install --upgrade pip
cd Scripts
pip install "Name of Package" such as pip install --module (package) --
Im on win10 and have 3.7, 3.8 and 3.10 installed.
For me "python" launches version 3.10 and does not accept commands (like -3.7), "py" launches newest version but does accept commands, and "python3" does nothing.
Uninstalled 3.10 and "python" now does nothing, and "py" launches 3.8.
I am unable to add a comment, but the mlink option presented in this answer above https://stackoverflow.com/a/55229666/8441472 by #Stanislav preserves cross-platform shebangs at the top of scripts (#!/usr/bin/env python3) and launches the right python.
(Even if you install python from python.org, Windows will direct you to the app marketplace nowadays if you type python3 on the command line. If you type python on the same cli it will launch the python.org version repl. It leads to scripts that generate no output, but more likely silently failed completely. I don't know ho common this is but have experienced it on a couple of different devices)
If you have this at the top of your script to ensure you launch python3 and don't feel like editing everything you own, it is not a bad approach at all... lol.
From the research I did for the topic, I saw some recommendations to install tty.js with npm, but it wouldn't install as well - some sort of python exe missing from the system error.
I am able to run the program from Git CMD but it is all confusing for me because I am familiar with unix based consoles :(
The way I installed node.js and npm : All was doen with the installer provided by node.js.
Any insights? Thank you in advance!
I have installed tty.js in a linux enviroment and it works great, you should some building essentials installed, such as:
gcc
g++
make
As well as Python 2.7. When installing using npm, it will look for all the dependencies and as I understand it will compile some C code that does the magic behind the scenes. I haven't tried it on Windows, but what I have seen there is the C code designed for windows, so it probably will run.
Maybe I will be of more help if you copy what you get on the npm installation.
have you tried using Git Bash? That is what I used for the most part as well and acts more unix like. If you're on a PC, an alternative is using ConEMU as they give you a shell that is unix like. Just wanted to give you some options if you're still running into trouble, I know this is super late :)