使用setx的缺点很少，尤其是当您尝试附加到环境变量（例如setx PATH％Path％; C：\ mypath）时，这将在每次运行时重复附加到路径中，这可能是一个问题。更糟糕的是，它无法区分机器路径（存储在HKEY_LOCAL_MACHINE中）和用户路径（存储在HKEY_CURRENT_USER中）。您在命令提示符处看到的环境变量由这两个值的串联组成。因此，在调用setx之??前：
user PATH == u
machine PATH == m
%PATH% == m;u
> setx PATH %PATH%;new
Calling setx sets the USER path by default, hence Now:
user PATH == m;u;new
machine PATH == m
%PATH% == m;m;u;new
每次调用setx追加到PATH时，系统路径都会不可避免地在％PATH％环境变量中重复。这些更改是永久性的，永远不会通过重新启动进行重置，因此会在计算机的整个生命周期内不断累积。
试图在DOS中弥补这一点超出了我的能力范围。所以我转向了Python。我今天想出的解决方案，是通过调整注册表来设置环境变量，包括追加到PATH而不引入重复项，如下所示：
from os import system, environ
import win32con
from win32gui import SendMessage
from _winreg import (
CloseKey, OpenKey, QueryValueEx, SetValueEx,
HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE,
KEY_ALL_ACCESS, KEY_READ, REG_EXPAND_SZ, REG_SZ
)
def env_keys(user=True):
if user:
root = HKEY_CURRENT_USER
subkey = 'Environment'
else:
root = HKEY_LOCAL_MACHINE
subkey = r'SYstem\CurrentControlSet\Control\Session Manager\Environment'
return root, subkey
def get_env(name, user=True):
root, subkey = env_keys(user)
key = OpenKey(root, subkey, 0, KEY_READ)
try:
value, _ = QueryValueEx(key, name)
except WindowsError:
return ''
return value
def set_env(name, value):
key = OpenKey(HKEY_CURRENT_USER, 'Environment', 0, KEY_ALL_ACCESS)
SetValueEx(key, name, 0, REG_EXPAND_SZ, value)
CloseKey(key)
SendMessage(
win32con.HWND_BROADCAST, win32con.WM_SETTINGCHANGE, 0, 'Environment')
def remove(paths, value):
while value in paths:
paths.remove(value)
def unique(paths):
unique = []
for value in paths:
if value not in unique:
unique.append(value)
return unique
def prepend_env(name, values):
for value in values:
paths = get_env(name).split(';')
remove(paths, '')
paths = unique(paths)
remove(paths, value)
paths.insert(0, value)
set_env(name, ';'.join(paths))
def prepend_env_pathext(values):
prepend_env('PathExt_User', values)
pathext = ';'.join([
get_env('PathExt_User'),
get_env('PathExt', user=False)
])
set_env('PathExt', pathext)
set_env('Home', '%HomeDrive%%HomePath%')
set_env('Docs', '%HomeDrive%%HomePath%\docs')
set_env('Prompt', '$P$_$G$S')
prepend_env('Path', [
r'%systemDrive%\cygwin\bin', # Add cygwin binaries to path
r'%HomeDrive%%HomePath%\bin', # shortcuts and 'pass-through' bat files
r'%HomeDrive%%HomePath%\docs\bin\mswin', # copies of standalone executables
])
# allow running of these filetypes without having to type the extension
prepend_env_pathext(['.lnk', '.exe.lnk', '.py'])
它不会影响当前进程或父Shell，但会影响运行后打开的所有cmd窗口，而无需重新启动，并且可以安全地进行编辑和重新运行多次，而不会引入任何重复项。
602392714
清零编程群