How do I permanently add the path to system's environment variable "PATH"?
I want to only add the path if it does not already exist.
Also I want to remove all paths that contain a folder name such as \myprogram whether it be:
C:\path\to\myprogram\dist; or D:\another\path\to\myprogram\dist;
Here's something that does what you want which is similar to code in the jaraco.windows project. And like it, only uses built-in Python modules—so doesn't require first downloading and installing the pywin32 extensions. Plus it's Python 2.6+ and 3.x compatible and supports Unicode environment variables and values (directory paths in this case).
Note that Windows administrator rights are required to change the permanent system-level environment variables.
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))
Sample usage:
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'))
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')
There is a python package pathtub (I am the author), which can do the job. You can read the code and docs on GitHub.
pip install pathtub
Reading Path
from pathtub import get_path
# Getting path (can be 'process' (default), 'user' or 'machine')
user_path = get_path('user')
print(user_path)
# C:\Program Files\Java\jdk-13.0.1\bin;C:\Programs;C:\Programs\apache-maven-3.6.2\bin;C:\Programs\cloc;C:\Programs\fciv;C:\Python\Python37;C:\Python\Python37\lib\site-packages\pywin32_system32;C:\Python\Python37\Scripts;C:\texlive\2018\bin\win32;C:\Users\USER\AppData\Local\Microsoft\WindowsApps;C:\Users\USER\AppData\Local\Programs\Microsoft VS Code\bin;C:\Users\USER\AppData\Roaming\npm
Adding to path
from pathtub import add_to_path
added = add_to_path(r'C:\Add this folder\to user path', mode='user')
print(added)
#True
# Adding duplicate entries is prevented
added = add_to_path(r'C:\Add this folder\to user path', mode='user')
print(added)
#False
Removing from Path
removed = remove_from_path(r'C:\Add this folder\to user path', mode='user')
print(removed)
#True
# Removing non-existing folder just returns False
removed = remove_from_path(r'C:\Add this folder\to user path', mode='user')
print(removed)
#False
Current implementation (v.1.1.2) uses Powershell for the permanent Path modifications. I have only tested this with newer (Python 3.7 and 3.8), but I guess it should work also on some older versions.
I am inferring from the paths in your question that your are interested in doing this on the Windows platform.
The documentation describes the process:
To programmatically add or modify system environment variables, add them to the HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Environment registry key, then broadcast a WM_SETTINGCHANGE message with lParam set to the string "Environment". This allows applications, such as the shell, to pick up your updates.
You should check os.environ. It's a dictionary that can be manipulated directly or via os.putenv:
Set the environment variable named varname to the string value. Such changes to the environment affect subprocesses started with os.system(), popen() or fork() and execv().
Hence:
>>> 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'
[update]
according to this answer you can make them persistent via windows registry
