Adding Python Path on Windows 7

Question

I\'ve been trying to add the Python path to the command line on Windows 7, yet no matter the method I try, nothing seems to work. I\'ve used the set command, I\

Answer 1

The following program will add the python executable path and the subdir Scripts (which is where e.g. pip and easy_install are installed) to your environment. It finds the path to the python executable from the registry key binding the .py extension. It will remove old python paths in your environment. Works with XP (and probably Vista) as well. It only uses modules that come with the basic windows installer.

# coding: utf-8

import sys
import os
import time
import _winreg
import ctypes

def find_python():
    """
    retrieves the commandline for .py extensions from the registry
    """
    hKey = _winreg.OpenKey(_winreg.HKEY_CLASSES_ROOT,
                           r'Python.File\shell\open\command')
    # get the default value
    value, typ = _winreg.QueryValueEx (hKey, None)
    program = value.split('"')[1]
    if not program.lower().endswith(r'\python.exe'):
        return None
    return os.path.dirname(program)

def extend_path(pypath, remove=False, verbose=0, remove_old=True,
                script=False):
    """
    extend(pypath) adds pypath to the PATH env. variable as defined in the
    registry, and then notifies applications (e.g. the desktop) of this change.
    !!! Already opened DOS-Command prompts are not updated. !!!
    Newly opened prompts will have the new path (inherited from the 
    updated windows explorer desktop)
    options:
    remove (default unset), remove from PATH instead of extend PATH
    remove_old (default set), removes any (old) python paths first
    script (default unset), try to add/remove the Scripts subdirectory 
        of pypath (pip, easy_install) as well
    """
    _sd = 'Scripts' # scripts subdir
    hKey = _winreg.OpenKey (_winreg.HKEY_LOCAL_MACHINE,
               r'SYSTEM\CurrentControlSet\Control\Session Manager\Environment',
               0, _winreg.KEY_READ | _winreg.KEY_SET_VALUE)

    value, typ = _winreg.QueryValueEx (hKey, "PATH")
    vals = value.split(';')
    assert isinstance(vals, list)
    if not remove and remove_old:
        new_vals = []
        for v in vals:
            pyexe = os.path.join(v, 'python.exe')
            if v != pypath and os.path.exists(pyexe):
                if verbose > 0:
                    print 'removing from PATH:', v
                continue
            if script and v != os.path.join(pypath, _sd) and \
               os.path.exists(v.replace(_sd, pyexe)):
                if verbose > 0:
                    print 'removing from PATH:', v
                continue
            new_vals.append(v)
        vals = new_vals
    if remove:
        try:
            vals.remove(pypath)
        except ValueError:
            if verbose > 0:
                print 'path element', pypath, 'not found'
            return
        if script:
            try:
                vals.remove(os.path.join(pypath, _sd))
            except ValueError:
                pass
            print 'removing from PATH:', pypath
    else:
        if pypath in vals:
            if verbose > 0:
                print 'path element', pypath, 'already in PATH'
            return
        vals.append(pypath)
        if verbose > 1:
            print 'adding to PATH:', pypath
        if script:
            if not pypath + '\\Scripts' in vals:
                vals.append(pypath + '\\Scripts')
            if verbose > 1:
                print 'adding to PATH:', pypath + '\\Scripts'
    _winreg.SetValueEx(hKey, "PATH", 0, typ, ';'.join(vals) )
    _winreg.SetValueEx(hKey, "OLDPATH", 0, typ, value )
    _winreg.FlushKey(hKey)
    # notify other programs
    SendMessage = ctypes.windll.user32.SendMessageW
    HWND_BROADCAST = 0xFFFF
    WM_SETTINGCHANGE = 0x1A
    SendMessage(HWND_BROADCAST, WM_SETTINGCHANGE, 0, u'Environment')
    if verbose > 1:
        print 'Do not forget to restart any command prompts'

if __name__ == '__main__':
    remove = '--remove' in sys.argv
    script = '--noscripts' not in sys.argv
    extend_path(find_python(), verbose=2, remove=remove, script=script)