从Python修改Windows环境变量的接口
我想知道怎么在Python脚本中永久性地修改Windows的环境变量。（这是setup.py脚本）
我在找一个标准的函数或者模块来实现这个功能。我已经知道了通过注册表来做的方法，但如果有其他建议也很欢迎。
6 个回答
4
我记得大约在千年之前，我尝试通过一个程序来改变当前DOS会话的环境。问题是：这个程序是在自己的DOS环境中运行的，所以它必须对其父环境进行操作。它就像在散步，从DOS信息块开始，一路沿着内存控制块的链条，找到那个父环境的位置。一旦我搞清楚了怎么做，我对操作环境变量的需求就消失了。下面我会给你提供Turbo Pascal的代码，但我想至少有三种更好的方法可以实现这个功能：
创建一个批处理文件，步骤是：(a) 调用一个Python脚本（或其他任何程序），这个脚本生成一个临时的批处理文件，里面包含合适的SET命令；(b) 调用这个临时批处理文件（SET命令会在当前的环境中执行）；(c) 删除这个临时批处理文件。
创建一个Python脚本，输出类似于 "VAR1=val1\nVAR2=val2\nVAR3=val3\n" 的内容到标准输出。你可以在批处理文件中这样使用它：
for /f "delims=|" %%X in ('callYourPythonScript') do set %%X这样就完成了：变量VAR1、VAR2和VAR3都被赋值了。
修改Windows注册表，并按照这里的描述，广播设置的更改，作者是Alexander Prokofyev。
接下来是Pascal代码（你可能需要一本荷兰语词典和一本Pascal编程书），这个程序只是报告内存位置。它似乎仍然可以在Windows XP下运行，尽管报告我们正在运行DOS 5.00。这只是一个开始，还有很多底层编程需要做，以便操作所选的环境。虽然指针结构看起来是正确的，但我不太确定1994年的环境模型现在是否仍然适用……
program MCBKETEN;
uses dos, HexConv;
{----------------------------------------------------------------------------}
{ Programma: MCBKETEN.EXE }
{ Broncode : MCBKETEN.PAS }
{ Doel : Tocht langs de MCB's met rapportage }
{ Datum : 11 januari 1994 }
{ Auteur : Meindert Meindertsma }
{ Versie : 1.00 }
{----------------------------------------------------------------------------}
type
MCB_Ptr = ^MCB;
{ MCB_PtrPtr = ^MCB_Ptr; vervallen wegens DOS 2.11 -- zie verderop }
MCB = record
Signatuur : char;
Eigenaar : word;
Paragrafen : word;
Gereserveerd : array[1..3] of byte;
Naam : array[1..8] of char;
end;
BlokPtr = ^BlokRec;
BlokRec = record
Vorige : BlokPtr;
DitSegment,
Paragrafen : word;
Signatuur : string[6];
Eigenaar,
Omgeving : word;
Functie : String4;
Oorsprong,
Pijl : char;
KorteNaam : string[8];
LangeNaam : string;
Volgende : BlokPtr;
end;
PSP_Ptr = ^PSP;
PSP = record
Vulsel1 : array[1..44] of byte;
Omgeving : word;
Vulsel2 : array[47..256] of byte;
end;
var
Zone : string[5];
ProgGevonden,
EindeKeten,
Dos3punt2 : boolean;
Regs : registers;
ActMCB : MCB_Ptr;
EersteSchakel, Schakel,
LaatsteSchakel : BlokPtr;
ActPSP : PSP_Ptr;
EersteProg,
Meester, Ouder,
TerugkeerSegment,
TerugkeerOffset,
TerugkeerSegment2,
OuderSegment : word;
Specificatie : string[8];
ReleaseNummer : string[2];
i : byte;
{----------------------------------------------------------------------------}
{ PROCEDURES EN FUNCTIES }
{----------------------------------------------------------------------------}
function Coda (Omgeving : word; Paragrafen : word) : string;
var
i : longint;
Vorige, Deze : char;
Streng : string;
begin
i := 0;
Deze := #0;
repeat
Vorige := Deze;
Deze := char (ptr (Omgeving, i)^);
inc (i);
until ((Vorige = #0) and (Deze = #0)) or (i div $10 >= Paragrafen);
if (i + 3) div $10 < Paragrafen then begin
Vorige := char (ptr (Omgeving, i)^);
inc (i);
Deze := char (ptr (Omgeving, i)^);
inc (i);
if (Vorige = #01) and (Deze = #0) then begin
Streng := '';
Deze := char (ptr (Omgeving, i)^);
inc (i);
while (Deze <> #0) and (i div $10 < Paragrafen) do begin
Streng := Streng + Deze;
Deze := char (ptr (Omgeving, i)^);
inc (i);
end;
Coda := Streng;
end
else Coda := '';
end
else Coda := '';
end {Coda};
{----------------------------------------------------------------------------}
{ HOOFDPROGRAMMA }
{----------------------------------------------------------------------------}
BEGIN
{----- Initiatie -----}
Zone := 'Lower';
ProgGevonden := FALSE;
EindeKeten := FALSE;
Dos3punt2 := (dosversion >= $1403) and (dosversion <= $1D03);
Meester := $0000;
Ouder := $0000;
Specificatie[0] := #8;
str (hi (dosversion) : 2, ReleaseNummer);
if ReleaseNummer[1] = ' ' then ReleaseNummer[1] := '0';
{----- Pointer naar eerste MCB ophalen ------}
Regs.AH := $52; { functie $52 geeft adres van DOS Info Block in ES:BX }
msdos (Regs);
{ ActMCB := MCB_PtrPtr (ptr (Regs.ES, Regs.BX - 4))^; NIET onder DOS 2.11 }
ActMCB := ptr (word (ptr (Regs.ES, Regs.BX - 2)^), $0000);
{----- MCB-keten doorlopen -----}
new (EersteSchakel);
EersteSchakel^.Vorige := nil;
Schakel := EersteSchakel;
repeat
with Schakel^ do begin
DitSegment := seg (ActMCB^);
Paragrafen := ActMCB^.Paragrafen;
if DitSegment + Paragrafen >= $A000 then
Zone := 'Upper';
Signatuur := Zone + ActMCB^.Signatuur;
Eigenaar := ActMCB^.Eigenaar;
ActPSP := ptr (Eigenaar, 0);
if not ProgGevonden then EersteProg := DitSegment + 1;
if Eigenaar >= EersteProg
then Omgeving := ActPSP^.Omgeving
else Omgeving := 0;
if DitSegment + 1 = Eigenaar then begin
ProgGevonden := TRUE;
Functie := 'Prog';
KorteNaam[0] := #0;
while (ActMCB^.Naam[ ord (KorteNaam[0]) + 1 ] <> #0) and
(KorteNaam[0] < #8) do
begin
inc (KorteNaam[0]);
KorteNaam[ ord (KorteNaam[0]) ] :=
ActMCB^.Naam[ ord (KorteNaam[0]) ];
end;
if Eigenaar = prefixseg then begin
TerugkeerSegment := word (ptr (prefixseg, $000C)^);
TerugkeerOffset := word (ptr (prefixseg, $000A)^);
LangeNaam := '-----> Terminate Vector = ' +
WordHex (TerugkeerSegment) + ':' +
WordHex (TerugkeerOffset ) ;
end
else
LangeNaam := '';
end {if ÆProgØ}
else begin
if Eigenaar = $0008 then begin
if ActMCB^.Naam[1] = 'S' then
case ActMCB^.Naam[2] of
'D' : Functie := 'SysD';
'C' : Functie := 'SysP';
else Functie := 'Data';
end {case}
else Functie := 'Data';
KorteNaam := '';
LangeNaam := '';
end {if Eigenaar = $0008}
else begin
if DitSegment + 1 = Omgeving then begin
Functie := 'Env ';
LangeNaam := Coda (Omgeving, Paragrafen);
if EersteProg = Eigenaar then Meester := Omgeving;
end {if ÆEnvØ}
else begin
move (ptr (DitSegment + 1, 0)^, Specificatie[1], 8);
if (Specificatie = 'PATH=' + #0 + 'CO') or
(Specificatie = 'COMSPEC=' ) or
(Specificatie = 'OS=DRDOS' ) then
begin
Functie := 'Env' + chr (39);
LangeNaam := Coda (DitSegment + 1, Paragrafen);
if (EersteProg = Eigenaar) and
(Meester = $0000 )
then
Meester := DitSegment + 1;
end
else begin
if Eigenaar = 0
then Functie := 'Free'
else Functie := 'Data';
LangeNaam := '';
if (EersteProg = Eigenaar) and
(Meester = $0000 )
then
Meester := DitSegment + 1;
end;
end {else: not ÆEnvØ};
KorteNaam := '';
end {else: Eigenaar <> $0008};
end {else: not ÆProgØ};
{----- KorteNaam redigeren -----}
for i := 1 to length (KorteNaam) do
if KorteNaam[i] < #32 then KorteNaam[i] := '.';
KorteNaam := KorteNaam + ' ';
{----- Oorsprong vaststellen -----}
if EersteProg = Eigenaar
then Oorsprong := '*'
else Oorsprong := ' ';
{----- Actueel proces (uitgaande Pijl) vaststellen -----}
if Eigenaar = prefixseg
then Pijl := '>'
else Pijl := ' ';
end {with Schakel^};
{----- MCB-opeenvolging onderzoeken / schakelverloop vaststellen -----}
if (Zone = 'Upper') and (ActMCB^.Signatuur = 'Z') then begin
Schakel^.Volgende := nil;
EindeKeten := TRUE;
end
else begin
ActMCB := ptr (seg (ActMCB^) + ActMCB^.Paragrafen + 1, 0);
if ((ActMCB^.Signatuur <> 'M') and (ActMCB^.Signatuur <> 'Z')) or
($FFFF - ActMCB^.Paragrafen < seg (ActMCB^) )
then begin
Schakel^.Volgende := nil;
EindeKeten := TRUE;
end
else begin
new (LaatsteSchakel);
Schakel^.Volgende := LaatsteSchakel;
LaatsteSchakel^.Vorige := Schakel;
Schakel := LaatsteSchakel;
end {else: (ÆMØ or ÆZØ) and Æteveel_ParagrafenØ};
end {else: ÆLowerØ or not ÆZØ};
until EindeKeten;
{----- Terugtocht -----}
while Schakel <> nil do with Schakel^ do begin
{----- Ouder-proces vaststellen -----}
TerugkeerSegment2 := TerugkeerSegment + (TerugkeerOffset div $10);
if (DitSegment <= TerugkeerSegment2) and
(DitSegment + Paragrafen >= TerugkeerSegment2)
then
OuderSegment := Eigenaar;
{----- Meester-omgeving markeren -----}
if DitSegment + 1 = Meester then Oorsprong := 'M';
{----- Schakel-verloop -----}
Schakel := Schakel^.Vorige;
end {while Schakel <> nil};
{----- Rapportage -----}
writeln ('Chain of Memory Control Blocks in DOS version ',
lo (dosversion), '.', ReleaseNummer, ':');
writeln;
writeln ('MCB@ #Par Signat PSP@ Env@ Type !! Name File');
writeln ('---- ---- ------ ---- ---- ---- -- -------- ',
'-----------------------------------');
Schakel := EersteSchakel;
while Schakel <> nil do with Schakel^ do begin
{----- Ouder-omgeving vaststellen -----}
if Eigenaar = OuderSegment then begin
if not Dos3punt2 then begin
if (Functie = 'Env ') then begin
Ouder := DitSegment + 1;
Pijl := 'Û';
end
else
Pijl := '<';
end {if not Dos3punt2}
else begin
if ((Functie = 'Env' + chr (39)) or (Functie = 'Data')) and
(Ouder = $0000)
then begin
Ouder := DitSegment + 1;
Pijl := 'Û';
end
else
Pijl := '<';
end {else: Dos3punt2};
end {with Schakel^};
{----- Keten-weergave -----}
writeln (WordHex (DitSegment) , ' ',
WordHex (Paragrafen) , ' ',
Signatuur , ' ',
WordHex (Eigenaar) , ' ',
WordHex (Omgeving) , ' ',
Functie , ' ',
Oorsprong, Pijl , ' ',
KorteNaam , ' ',
LangeNaam );
{----- Schakel-verloop -----}
Schakel := Schakel^.Volgende;
end {while Schakel <> nil};
{----- Afsluiting rapportage -----}
writeln;
write ('* = First command interpreter at ');
if ProgGevonden
then writeln (WordHex (EersteProg), ':0000')
else writeln ('?');
write ('M = Master environment at ');
if Meester > $0000
then writeln (WordHex (Meester), ':0000')
else writeln ('?');
write ('< = Parent proces at ');
writeln (WordHex (OuderSegment), ':0000');
write ('Û = Parent environment at ');
if Ouder > $0000
then writeln (WordHex (Ouder), ':0000')
else writeln ('?');
writeln ('> = Current proces at ',
WordHex (prefixseg), ':0000');
writeln (' returns to ',
WordHex (TerugkeerSegment), ':', WordHex (TerugkeerOffset));
END.
(在ASCII 127以上，可能会有一些ASCII/ANSI转换问题。)
5
使用外部的Windows setx 命令其实也很简单：
C:\>set NEWVAR
Environment variable NEWVAR not defined
C:\>python
Python 2.5.4 (r254:67916, Dec 23 2008, 15:10:54) [MSC v.1310 32 bit (Intel)] on
win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.system('setx NEWVAR newvalue')
0
>>> os.getenv('NEWVAR')
>>> ^Z
C:\>set NEWVAR
Environment variable NEWVAR not defined
现在打开一个新的命令提示符窗口：
C:\>set NEWVAR
NEWVAR=newvalue
你可以看到，setx 命令并不会为当前的会话设置变量，也不会为父进程（也就是第一个命令提示符）设置变量。但是，它会在注册表中持久性地设置这个变量，以便未来的进程使用。
我觉得没有办法去改变父进程的环境变量（如果有的话，我很想知道！）。
26
使用setx有一些缺点，特别是当你想要在环境变量中添加内容时（比如说，setx PATH %Path%;C:\mypath）。每次运行这个命令时，它都会重复地把内容添加到路径中，这可能会造成问题。更糟糕的是，它并不能区分机器路径（存储在HKEY_LOCAL_MACHINE）和用户路径（存储在HKEY_CURRENT_USER）。在命令提示符下看到的环境变量是这两个值的组合。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
每次你调用setx来添加内容到PATH时，系统路径在%PATH%环境变量中不可避免地会重复。这些更改是永久性的，不会因为重启而重置，并且会随着机器的使用时间而不断累积。
我尝试在DOS中解决这个问题，但超出了我的能力范围。所以我转向了Python。今天我想出的解决方案是通过修改注册表来设置环境变量，包括在PATH中添加内容而不引入重复项，具体方法如下：
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'])
这个方法不会影响当前的进程或父级命令行窗口，但会影响在运行后打开的所有cmd窗口，无需重启，并且可以安全地多次编辑和运行，而不会引入任何重复项。