Since Python isn't in your system PATH and the usual where python or python --version commands aren't working, let's focus on verifying file associations and leveraging Windows' built-in tools to get your script running. Here are practical, reliable methods:

1. Check & Use File Associations (Most Direct) #

Windows uses assoc and ftype to manage which programs open specific file types. We can use these commands to confirm .py files are linked to Python, then extract the executable path:

@echo off
setlocal enabledelayedexpansion

:: Step 1: Verify .py extension is associated
assoc .py >nul 2>&1
if errorlevel 1 (
    echo Error: .py extension has no associated program.
    goto :cleanup
)

:: Step 2: Get the file type linked to .py
for /f "tokens=2 delims==" %%a in ('assoc .py') do (
    set "PY_FILE_TYPE=%%a"
)

:: Step 3: Check if the file type has an executable command
ftype !PY_FILE_TYPE! >nul 2>&1
if errorlevel 1 (
    echo Error: No executable linked to !PY_FILE_TYPE!.
    goto :cleanup
)

:: Step 4: Extract the Python executable path from the association
for /f "tokens=2 delims==" %%b in ('ftype !PY_FILE_TYPE!') do (
    set "PY_CMD=%%b"
)
:: Strip quotes from the path (if present)
for /f "tokens=1 delims= " %%c in ("!PY_CMD!") do (
    set "PY_PATH=%%c"
)
set "PY_PATH=!PY_PATH:"=!"

:: Step 5: Confirm the executable exists
if not exist "!PY_PATH!" (
    echo Error: Python path from registry is invalid: !PY_PATH!
    goto :cleanup
)

:: Success! Run your script
echo Python found at: !PY_PATH!
echo Running your script...
"!PY_PATH!" "your_script.py"

:cleanup
endlocal

2. Test Direct Execution of .py Files #

If Python's installer set up file associations correctly, you can simply try running a test script to confirm functionality. Create a tiny test file named test_py.py with this content:

import sys
sys.exit(0)  # Exit with success code

Then use this batch code to check:

@echo off

:: Try running the test script
test_py.py >nul 2>&1
if errorlevel 1 (
    echo Error: .py files can't be executed properly.
) else (
    echo .py files are executable! Running your script...
    your_script.py
)

Note: Make sure test_py.py is in the same directory as your batch file, or in a directory that's in your current PATH.

3. Use the Python Launcher (py.exe) #

Python 3.3+ includes a launcher (py.exe) that's usually installed to C:\Windows\System32—which is almost always in the system PATH. Even if Python itself isn't in PATH, this launcher can find installed Python versions. Test it with this batch code:

@echo off

:: Check if py launcher is available
py --version >nul 2>&1
if not errorlevel 1 (
    echo Python launcher detected!
    echo Running your script...
    py your_script.py
    goto :end
)

echo Python launcher not found. Trying other methods...
:: Add fallback methods here if needed

:end

This is often the simplest solution if the launcher was installed (it's enabled by default in most Python installers).

4. Retrieve Path from Windows Registry #

Python writes its installation path to the Windows Registry during setup. We can query these entries to find the executable:

@echo off
setlocal enabledelayedexpansion

:: Check system-wide installations (HKLM)
reg query "HKLM\Software\Python\PythonCore" /s /v InstallPath >nul 2>&1
if not errorlevel 1 (
    for /f "skip=2 tokens=2*" %%a in ('reg query "HKLM\Software\Python\PythonCore" /s /v InstallPath') do (
        set "PY_PATH=%%b\python.exe"
        if exist "!PY_PATH!" (
            echo Found system Python at: !PY_PATH!
            "!PY_PATH!" "your_script.py"
            goto :cleanup
        )
    )
)

:: Check user-specific installations (HKCU)
reg query "HKCU\Software\Python\PythonCore" /s /v InstallPath >nul 2>&1
if not errorlevel 1 (
    for /f "skip=2 tokens=2*" %%a in ('reg query "HKCU\Software\Python\PythonCore" /s /v InstallPath') do (
        set "PY_PATH=%%b\python.exe"
        if exist "!PY_PATH!" (
            echo Found user Python at: !PY_PATH!
            "!PY_PATH!" "your_script.py"
            goto :cleanup
        )
    )
)

echo Error: No valid Python installation found in registry.

:cleanup
endlocal

Note: This works for standard CPython installations. Third-party distributions like Anaconda may use different registry paths.

内容的提问来源于stack exchange，提问作者Map Man