如何添加和刪除系統環境變量「PATH」？

Question

我該如何永久添加系統環境變量「路徑」的路徑？

我想只添加路徑，如果它不存在。

另外我想刪除包含的文件夾名稱，如\myprogram無論是所有路徑：

C:\path\to\myprogram\dist;或D:\another\path\to\myprogram\dist;

Answer 1

import _winreg as reg 
import win32gui 
import win32con 


# read the value 
key = reg.OpenKey(reg.HKEY_CURRENT_USER, 'Environment', 0, reg.KEY_ALL_ACCESS) 
# use this if you need to modify the system variable and if you have admin privileges 
#key = reg.OpenKey(reg.HKEY_LOCAL_MACHINE, r'SYSTEM\CurrentControlSet\Control\Session Manager\Environment', 0, reg.KEY_ALL_ACCESS) 
try 
    value, _ = reg.QueryValueEx(key, 'PATH') 
except WindowsError: 
    # in case the PATH variable is undefined 
    value = '' 

# modify it 
value = ';'.join([s for s in value.split(';') if not r'\myprogram' in s]) 

# write it back 
reg.SetValueEx(key, 'PATH', 0, reg.REG_EXPAND_SZ, value) 
reg.CloseKey(key) 

# notify the system about the changes 
win32gui.SendMessage(win32con.HWND_BROADCAST, win32con.WM_SETTINGCHANGE, 0, 'Environment') 

Answer 2

我從你的問題，你有興趣做這個路徑推斷在Windows平臺上。

的documentation描述的過程：

以編程方式添加或修改系統環境變量，把它們添加到HKEY_LOCAL_MACHINE \系統\ CurrentControlSet \控制\會話管理\環境的註冊表項，然後廣播用WM_SETTINGCHANGE消息lParam設置爲字符串「Environment」。這使應用程序（如shell）能夠獲取更新。

Answer 3

您應該檢查os.environ。這是一個字典，可以直接或通過os.putenv：

將名爲varname的環境變量設置爲字符串值。 對環境所做的更改會影響以 os.system（），popen（）或fork（）和execv（）開頭的子流程。

因此：

>>> import os 
>>> os.environ["PATH"] = path_old + ":/tmp/hallo" 
>>> os.environ["PATH"] 
'/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/vendor_perl:/usr/bin/core_perl:/tmp/hallo' 

[更新]

根據to this answer你可以讓他們通過Windows註冊表持久

Answer 4

這裏的東西，你想要做什麼是類似於jaraco.windows項目中的代碼。就像它一樣，只使用內置的Python模塊 - 因此不需要先下載並安裝pywin32擴展。 加上Python 2.6+和3.x兼容，並支持Unicode環境變量和值（在這種情況下爲目錄路徑）。

請注意，需要Windows管理員權限才能更改永久系統級環境變量。

import ctypes 
from ctypes.wintypes import HWND, UINT, WPARAM, LPARAM, LPVOID 
LRESULT = LPARAM # synonymous 
import os 
import sys 
try: 
    import winreg 
    unicode = str 
except ImportError: 
    import _winreg as winreg # Python 2.x 

class Environment(object): 
    path = r'SYSTEM\CurrentControlSet\Control\Session Manager\Environment' 
    hklm = winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE) 
    key = winreg.OpenKey(hklm, path, 0, winreg.KEY_READ | winreg.KEY_WRITE) 
    SendMessage = ctypes.windll.user32.SendMessageW 
    SendMessage.argtypes = HWND, UINT, WPARAM, LPVOID 
    SendMessage.restype = LRESULT 
    HWND_BROADCAST = 0xFFFF 
    WM_SETTINGCHANGE = 0x1A 
    NO_DEFAULT_PROVIDED = object() 

    def get(self, name, default=NO_DEFAULT_PROVIDED): 
     try: 
      value = winreg.QueryValueEx(self.key, name)[0] 
     except WindowsError: 
      if default is self.NO_DEFAULT_PROVIDED: 
       raise ValueError("No such registry key", name) 
      value = default 
     return value 

    def set(self, name, value): 
     if value: 
      winreg.SetValueEx(self.key, name, 0, winreg.REG_EXPAND_SZ, value) 
     else: 
      winreg.DeleteValue(self.key, name) 
     self.notify() 

    def notify(self): 
     self.SendMessage(self.HWND_BROADCAST, self.WM_SETTINGCHANGE, 0, u'Environment') 

Environment = Environment() # singletion - create instance 

PATH_VAR = 'PATH' 

def append_path_envvar(addpath): 
    def canonical(path): 
     path = unicode(path.upper().rstrip(os.sep)) 
     return winreg.ExpandEnvironmentStrings(path) # Requires Python 2.6+ 
    canpath = canonical(addpath) 
    curpath = Environment.get(PATH_VAR, '') 
    if not any(canpath == subpath 
       for subpath in canonical(curpath).split(os.pathsep)): 
     Environment.set(PATH_VAR, os.pathsep.join((curpath, addpath))) 

def remove_envvar_path(folder): 
    """ Remove *all* paths in PATH_VAR that contain the folder path. """ 
    curpath = Environment.get(PATH_VAR, '') 
    folder = folder.upper() 
    keepers = [subpath for subpath in curpath.split(os.pathsep) 
       if folder not in subpath.upper()] 
    Environment.set(PATH_VAR, os.pathsep.join(keepers)) 

使用範例：

print(Environment.get('path')) 
append_path_envvar(r'C:\path\to\myprogram\dist') 
append_path_envvar(r'D:\another\path\to\myprogram\dist') 
print(Environment.get('path')) 
remove_envvar_path(r'\myprogram') # remove *both* added paths 
print(Environment.get('path'))