How to load non-default version of python in command line - python

I have 2 different versions of python installed on my system i.e. 2.6.6 and 2.7.9.
I am running python scripts on linux via QTP(using paramiko on windows). I execute the following sample of code to execute commands.
"python /dir/of/frameword/ somecode"
When I hit this command the default version of python is used to create the shell that is 2.6.6
Is there any way that I could instruct the linux to pick up 2.7.9 with a command like "python27".
I have also added an alias in ./bashrc but that also dosent help.

set up a shell alias
alias python=/usr/local/bin/python2.7
PS:have you run source ~/.bashrc after save ~/.bashrc?I noticed you mention ./bashrc instead of ~/.bashrc,is it a spelling mistake?
use virtualenv

Related

How to change python path from anaconda to default

I installed Anaconda and now there's a (base) before the shell username in the terminal. I am also not able to use the default python by python command in the terminal as it calls the anaconda python. Also can't switch the python interpreter in vs code. (Nothing happens when I try)Any way I can reset it back. I have python 3.8.2 as default in my Linux fedora os.
Thank You
You can go to your bashrc
/etc/bashrc
and add a new alias for your default python location which you'll use for calling default python.
alias python_default='.../bin/python3'
alias python_conda='.../bin/python3'

Simulate python3 shell commands behavior in windows powershell

I work on an api that run python3 scripts like python3 <scriptname.py>. This api initially run on a linux system. Unfortunately I make the local development of it on a windows. Is there a way to simulate this behaviour so that when I run in powershell python3 -V it give me the version of python.
I have allready python 3 installed on my computer. I tried to add the path to my python.exe to the system variables with for variable the string python3. But after registering and restarting powershell and type python3 -V I still get the error that «python3» is not recognized as a command applet name.
Does anyone have any ideas?
Once python is in your path, you can define a PowerShell alias for python3.
PS > New-Alias python3 python
PS > python3 -V
python 3.6.5
In order to have this alias as a permanent one, refer to this question: Permanent PowerShell Aliases.
I found tricky solution.
Once python is in your path, go to python installed path and copy python.exe and named duplicated one as python3.exe

Python 3 installation on windows running from command line

Just curious, is there a particular reason why Python 3.x is not installed on Windows to run default with the command line "python3", like it does on Mac OSX and Linux? Is there some kind of way to configure Python so that it runs like this? Thanks.
EDIT: Just to add, the reason I am asking is because I have both the Python 2 and 3 interpreter installed on my computer, and so it is ambiguous, as both are run using the command "python".
the reason I am asking is because I have both the Python 2 and 3 interpreter installed on my computer, and so it is ambiguous, as both are run using the command "python".
To run Python 2 executable:
C:\> py -2
To run Python 3 executable:
C:\> py -3
where py is a Python launcher that is bundled with your Python 3 installation.
py recognizes the shebang (e.g., #!/usr/bin/env python3 causes Python 3 executable to be run), it respects virtualenv (if you run py without specifying the explicit python executable version) i.e., run:
C:\> py your_script.py
and the correct python version is used automatically -- you don't need to specify the Python version on the command-line explicitly.
is there a particular reason why Python 3.x is not installed on Windows to run default with the command line "python3", like it does on Mac OSX and Linux?
OSX and Linux have python executable installed by default as a rule and it refers to Python 2 version in most cases at the moment that is why you need a separate python3 name there.
There is no Python on Windows by default. And therefore any version that you've installed is just python (I guess). The recommended way to manage multiple python versions is to use the Python launcher.
Is there some kind of way to configure Python so that it runs like this?
If you want to type python3 some_script.py instead of py some_script.py or even just some_script (assuming .py is in %PATHEXT% and Python launcher is configured to run Python scripts (check assoc .py and ftype Python.File) -- the default) then create a bat-file e.g., python3.cmd and put it in %PATH%:
"C:\path to\Python 3.X\python.exe" %*
You likely missed the checkbox at the bottom of the installer.
Full documentation here: https://docs.python.org/3/using/windows.html
Then, I think you just run python, not python3 from the Command Prompt. The reason Unix systems have python3 is because python defaults to Python2.x in many systems.
You have to add the python bin folder to your path. You can do it manually but when you install python i remember you have an option to do that.
I work with multiple Python 2.x and 3.x distros on Windows. Some of them are "portable" - i.e. not recorded in the Windows registry, and therefore not accessible by the version-selector py.exe delivered with Python 3.3+. To save my sanity, I wrote SelectPython.bat which is available on bitbucket. It configures the PYTHONHOME, PYTHONPATH and PATH variables according to the target you give it (a relative or absolute path to the parent directory of python.exe). You can do so in a way that is sticky for the rest of your command-line session:
> SelectPython C:\Path\To\Desired\Version\Of\Python
> python
or transiently, i.e. to call a particular python command without otherwise affecting the environment of the shell you're calling it from:
> SelectPython C:\Path\To\Desired\Version\Of\Python python -c "import sys;print(sys.version)"
You may find it helpful.

Specify which version of Python runs in Automator?

In my terminal and in CodeRunner my Python is updated to 2.7.6 but when I ran a shell script in the OSX Automator I found that it is running 2.7.2
How can I update the Automator Python to 2.7.6 like the rest of my compilers ?
I couldn't specify explicitly which python for it to use.
So, I ran it in bash environment with following command:
$ your/python/path /path/to/your/python/script.py
And make sure first line of your python program contains the path to the python environment you wish to use.
Eg:
#! /usr/local/bin/python

Setting up Linux to use a certain version of python for compile

I'm running Ubuntu to compile a set of code which requires python 2.4.
How can I setup a terminal launcher so that when I open that launcher all python related commands will use python 2.4 instead of the python 2.6 that is defaulted in Ubuntu?
Set a bash alias in that shell session: alias python=python2.4 (assuming python2.4 is in your $PATH of course). This way you won't have to remember to explicitly type the 2.4 a zillion times in that terminal -- which is what bash aliases are for!-)
Invoke the interpreter via python2.4 instead of using the default.
For a permenant system wide change put a symbolic link to the version you want in place of /usr/bin/python. ie
rm /usr/bin/python;
ln -s /usr/bin/python2.4 /usr/bin/python
gentoo has a program 'eselect' which is for just this kind of thing (listing versions of programs and setting the default), Ubuntu may have something analogous; you'd have to check their docs.
Watch out for using the alias when wanting to use the python you want. If the python script uses $0 to figure out, how it was called, then uses that answer to execute another python script. The other script will be called with whatever version that matches the link name, not the version the link points to.

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