Trying to create a batch script for windows that runs a program with python3 if available else python2.
I know the script can be executed with $py -2 script.py
and py3 with $py -3 script.py.
and if I run py -0, it returns all the python versions.
How do I build this script?
I do not want to check if the python directory is available or not, I'd prefer to check in a way that is python location agnostic.
Not a full solution, but a method to detect which version of Python is installed:
You can check if Python 3 is installed by running py -3 --version and then checking the %ERRORLEVEL% variable in the batch script. If it is 0, then py -3 --version was successful, i.e. Python 3 is installed on the system. If it is nonzero, then Python 3 is not installed.
python.exe is not py.exe. python.exe does not support -0, -2 or -3 arguments. The Python Launcher py.exe does.py.exe in my python 2.7, but it's apparently not present !Piping directly python.exe --version to find or findstr is not working (with python 2.7).
Building dinamicaly and running a python script that return the version, will enable this piping !
The solution :
@echo off
set "$py=0"
call:construct
for /f "delims=" %%a in ('python #.py ^| findstr "2"') do set "$py=2"
for /f "delims=" %%a in ('python #.py ^| findstr "3"') do set "$py=3"
del #.py
goto:%$py%
echo python is not installed or python's path Path is not in the %%$path%% env. var
exit/b
:2
echo running with PY 2
exit/b
:3
echo running with PY 3
exit/b
:construct
echo import sys; print('{0[0]}.{0[1]}'.format(sys.version_info^)^) >#.py
python --version 2>&1 | findstr " 2.7" ? Seems to work for 2 and 3. No temporary file needed.You can do it without temporary file
set PYTHON_MAJOR_VERSION=0
for /f %%i in ('python -c "import sys; print(sys.version_info[0])"') do set PYTHON_MAJOR_VERSION=%%i
