Why isn't lib in Python 3 install DOS PATH? - python-3.x

I installed Python 3.4 on a 64-bit Windows 7 machine. Works fine. I did choose the option to have Python added to the DOS PATH environment variable so that I could work at DOS command line, write python .py and it would work without having to type the full Python installation directory.
But when I tried to use pydoc, I discovered that it didn't know where pydoc was. Why? Because only Python34 and Python34\scripts are in the PATH. Why not also Python34/lib which has all sorts of useful tools, including pydoc.py?

If the command isn't bound, for whatever reason, Invoke pydoc with -m, e.g.
python -h
python -m pydoc some_file.py

Related

I cannot run pyinstaller on my computer even though I have installed it

This is the problem right here, do you have any advice for that?
installed pip and pyinstaller, but still got this error message when I tried to convert my project into an .exe.
From Pyinstaller installation guide:
If you cannot use the pyinstaller command due to the scripts directory not being in PATH, you can instead invoke the PyInstaller module, by running python -m PyInstaller (pay attention to the module name, which is case sensitive). This form of invocation is also useful when you have PyInstaller installed in multiple python environments, and you cannot be sure from which installation the pyinstaller command will be ran.
So you may run it as e.g.:
python -m PyInstaller some_system.py
Or, as the issue seems that PATH Windows environment variable doesn't include Python's Script folder, it'd better to fix it. From the same guide:
If the command is not found, make sure the execution path includes the proper directory:
Windows: C:\PythonXY\Scripts where XY stands for the major and minor Python version number, for example C:\Python38\Scripts for Python 3.8)
To fix you may run where python to get exact location of Python on your machine (let's say it shows C:\Python38\). Then add to PATH env variable Scripts folder inside it (in this example it'd be C:\Python38\Scripts\)

How to execute python program made on IDE from command prompt

I usually use pycharm for coding.
My question is how I can replace execution by IDE to command prompt execution. IDE makes it easy to set all python environments.
Windows 10 / Anaconda 3 / Python 3.7
My goal is to execute python program by windows scheduler.
Please let me know how to execute it.
Thanks.
Just open a command prompt, and then type:
python path_to_your_code/your_code.py
If this gives you errors that numpy, pandas etc are not installed then it means that the interpreter being used by your IDE (where you did not get such errors) is not the same one pointed at by python in command line.
If you're using a virtual environment or a python installation other than the default one you can just replace the python with a full path to the python binary in the environment you are using. So assuming your IDE is using the Anaconda environment, try this from command line:
c:\Anaconda3\python.exe path_to_your_code\your_code.py
Adding c:\Anaconda3 to PATH will not help if you already have another version of Python installed elsewhere, it will just mean that you now have two python.exe files in your path and python will still point at the same one.
However if where python already returns the path above, it means that your IDE is not using this interpreter and you'll need to find which one it is using. You can check this by looking in the Project Interpreter options or by running this script
import sys
print(sys.executable)

'python3' is not recognized as an internal or external command, operable program or batch file

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.

How to set python 3.4 as default over 2.7 in dual installation

I recently downloaded version 3.4 and installed it but when I go to the command line and type python -V I get Python 2.7.6 How do I set python 3.4 as my default version.
The first step to do is to find where is your python.
You can do it with which or where command (which for unix where for windows). Once you have this information you will know what is actually executed as "python" command. Then you need to change it for windows (i believe) you need to change the PATH variable in such a way that your python 3.4 will be found earlier then 2.6
For the unix you need to either do the same or link it in your package manager.
You need to use python3 to use python 3.4. For example, to know version of Python use:
python3 -V
This will use python 3.4 to interpret your program or you can use the shebang to make it executable. The first line of your program should be:
#!/usr/bin/env python3
If you want python3 to be used when you type python on the terminal, you can use an alias. To add a new alias, open your ~/.bash_aliases file using gedit ~/.bash_aliases and type the following:
alias python=python3
and then save and exit and type
source ~/.bash_aliases
and then you can type
python -V
to use python3 as your default python interpreter.

Is there a way to alias a location in Cygwin for a shebang?

I have some scripts that I often use in both windows(cygwin) and linux, I'd like to make the scripts executable in both environments. Is there a way to alias the location of my python installation, for example so that
#!/usr/bin/python
will still find my python installation, even though, as far as cygwin is concerned, it is located at /cygdrive/c/Python26/python?
Just install Python via Cygwin's setup.exe, and it will be in /usr/bin.
Or create symbolic links on both systems, for example in /usr/local/bin/python, and use that in the shebang.
Or write an installation script that adjusts the #! line in your Python scripts as it installs them.
Note that if your /cygdrive/c/Python26/python (C:\Python26\python) is a native Windows Python installation, scripts using it won't be able to use Cygwin-style paths.
Put /cygdrive/c/Python26/python in your PATH variable, and replace the shebang line with
#!/usr/bin/env python
assuming that cygwin can run that version of python.

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